Pathologic findings and causes of death of stranded cetaceans in the Canary Islands (2006-2012)

Case Report: Ambergris coprolite and septicemia in a male sperm whale stranded in La Palma (Canary Islands)

On the 21st of May 2023, a dead adult male sperm whale (Physeter macrocephalus) of 13 m in length and estimated weight of around 18,000 kg was reportedly stranded at Playa Los Nogales, La Palma, Canary Islands, Spain. A necropsy was performed 48hpm. A 50 cm diameter and 9.5 kg coprolite was found obstructing the caudal colon-rectal lumen. Necro-hemorrhagic lesions were found in heart muscles and three different bacteria of intestinal origin were isolated and identified (Edwarsiella tarda, Hathewaya limosa and Clostridium perfringens). It is reported a lethal septicemia of intestinal origin associated with ambergris coprolite as cause of death in this sperm whale.

Navigating the unknown: assessing anthropogenic threats to beaked whales, family Ziphiidae

This review comprehensively evaluates the impacts of anthropogenic threats on beaked whales (Ziphiidae)-a taxonomic group characterized by cryptic biology, deep dives and remote offshore habitat, which have challenged direct scientific observation. By synthesizing information published in peer-reviewed studies and grey literature, we identified available evidence of impacts across 14 threats for each Ziphiidae species. Threats were assessed based on their pathways of effects on individuals, revealing many gaps in scientific understanding of the risks faced by beaked whales. By applying a comprehensive taxon-level analysis, we found evidence that all beaked whale species are affected by multiple stressors, with climate change, entanglement and plastic pollution being the most common threats documented across beaked whale species. Threats assessed as having a serious impact on individuals included whaling, military sonar, entanglement, depredation, vessel strikes, plastics and oil spills. This review emphasizes the urgent need for targeted research to address a range of uncertainties, including cumulative and population-level impacts. Understanding the evidence and pathways of the effects of stressors on individuals can support future assessments, guide practical mitigation strategies and advance current understanding of anthropogenic impacts on rare and elusive marine species.

Molecular Detection and Characterization of Mycoplasma spp. in Marine Mammals, Brazil

Mycoplasma spp. are wall-less bacteria able to infect mammals and are classified as hemotropic (hemoplasma) and nonhemotropic. In aquatic mammals, hemoplasma have been reported in California sea lions (Zalophus californianus) and river dolphins (Inia spp.). We investigated Mycoplasma spp. in blood samples of West Indian manatees (Trichechus manatus), pinnipeds (5 species), and marine cetaceans (18 species) that stranded or were undergoing rehabilitation in Brazil during 2002-2022. We detected Mycoplasma in blood of 18/130 (14.8%) cetaceans and 3/18 (16.6%) pinnipeds. All tested manatees were PCR-negative for Mycoplasma. Our findings indicate that >2 different hemoplasma species are circulating in cetaceans. The sequences from pinnipeds were similar to previously described sequences. We also detected a nonhemotropic Mycoplasma in 2 Franciscana dolphins (Pontoporia blainvillei) that might be associated with microscopic lesions. Because certain hemoplasmas can cause disease and death in immunosuppressed mammals, the bacteria could have conservation implications for already endangered aquatic mammals.

Viral skin diseases in odontocete cetaceans: gross, histopathological, and molecular characterization of selected pathogens

Fifty-five skin lesions from 31 stranded cetaceans along the Canary coasts (2011-2021) were submitted to macroscopic, histological, and molecular analyses to confirm infection by cetacean poxvirus, herpesvirus and cetacean morbillivirus. They were macroscopically categorized into eight categories with respective subcategories according to their color, shape, size, and consistency. Cetacean poxvirus was detected in 54.54% of the skin lesions through real-time and conventional PCRs based on the DNA polymerase gene. Additionally, herpesvirus and morbillivirus were currently detected from 43.63 and 1.82% of the cutaneous lesions, respectively. Coinfection of poxvirus and herpesvirus was detected in nine of them (16.36%), which makes the present study the first to report coinfection by both pathogens in skin lesions in cetaceans. A plausible approach to histopathological characterization of poxvirus-and herpesvirus-positive skin lesions was established. Hyperkeratosis, acanthosis, ballooning degeneration, and intracytoplasmic inclusion bodies in vacuolized keratinocytes through the stratum spinosum were common findings in poxvirus skin lesions. Alphaherpesvirus was associated with a prominent acanthotic epidermis, moderate necrosis, multifocal dyskeratosis, and irregular keratinocytes with both cellular and nuclei pleomorphism. The common histopathological findings of both pathogens were observed in coinfection lesions. However, those associated with herpesvirus were considerably more remarkable. Relationships between molecular and microscopic findings were observed for the lesions that showed tattoo-like and tortuous patterns. Further multidisciplinary diagnostic studies of infected skin lesions are needed to understand the epidemiology of these emerging infectious diseases.

Assessment of Harbour Porpoise Bycatch along the Portuguese and Galician Coast: Insights from Strandings over Two Decades

The Iberian harbour porpoise population is small and fisheries bycatch has been described as one of its most important threats. Data on harbour porpoise strandings collected by the Portuguese and Galician stranding networks between 2000 and 2020 are indicative of a recent mortality increase in the western Iberian coast (particularly in northern Portugal). Overall, in Portugal and Galicia, individuals stranded due to confirmed fishery interaction represented 46.98% of all analysed porpoises, and individuals stranded due to probable fishery interaction represented another 10.99% of all analysed porpoises. Considering the Portuguese annual abundance estimates available between 2011 and 2015, it was possible to calculate that an annual average of 207 individuals was removed from the population in Portuguese waters alone, which largely surpasses the potential biological removal (PBR) estimates (22 porpoises, CI: 12-43) for the same period. These results are conservative and bycatch values from strandings are likely underestimated. A structured action plan accounting for new activities at sea is needed to limit the Iberian porpoise population decline. Meanwhile, there is an urgent need for a fishing effort reorganization to directly decrease porpoise mortality.

Cetacean Intracytoplasmic Eosinophilic Globules: A Cytomorphological, Histological, Histochemical, Immunohistochemical, and Proteomic Characterization

The nature, etiopathogenesis, and clinicopathologic relevance of the prevalent intracytoplasmic eosinophilic globules (IEGs) within hepatocytes of cetaceans are unknown. This study aims to evaluate the presence and characterize the IEGs in the hepatocytes of cetaceans using histochemical and immunohistochemical electron microscopy, Western blot, lectin histochemistry, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry techniques. A total of 95/115 (83%) animals (16 species) exhibited histologically evident intracytoplasmic round to oval, single to multiple, hyaline eosinophilic globules within the hepatocytes. These globules were largely PAS-positive, diastase resistant, and were immunopositive for fibrinogen (FB, 97%), albumin (Alb, 85%), and α1-antitrypsine (A1AT, 53%). The IEG positivity for FB and A1AT were correlated with live-stranding, hepatic congestion and a good nutritional status. The cetaceans lacking IEGs were consistently dead stranded and had poor body conditions. The IEGs in 36 bycaught cetaceans were, all except one, FB-positive and A1AT-negative. The IEGs exhibited morphologic and compositional variations at the ultrastructural level, suggesting various stages of development and/or etiopathogenesis(es). The glycocalyx analysis suggested an FB- and A1AT-glycosylation pattern variability between cetaceans and other animals. The proteomic analyses confirmed an association between the IEGs and acute phase proteins, suggesting a relationship between acute stress (i.e., bycatch), disease, and cellular protective mechanisms, allowing pathologists to correlate this morphological change using the acute hepatocytic cell response under certain stress conditions.

Hypertrophic osteopathy in a common dolphin (Delphinus delphis) with concurrent pulmonary Halocercus delphini infestation

Dolphins are marine mammals that often live in coastal habitats. Common causes of severe skeletal disorders among wild dolphins are congenital vertebral anomalities, collisions with sea vessels, trauma, hunting-related injury, infectious diseases, environmental pollution, and tumors. A free-ranging male, 3-year-old common dolphin (Delphinus delphis) was found dead in the coast of Asturias in northern Spain. Postmortem examination revealed lordosis in the caudal vertebral column, while X-ray imaging and computer tomography showed well-organized palisade-like periosteal proliferation, appearing as florid-like accretions, along the spinous apophysis of 26 lumbar-caudal vertebrae. The transverse apophysis was affected on only a few caudal vertebrae. The cortical layer remained intact. Histology of vertebra tissue showed periosteal proliferation of cancellous bone. The animal was diagnosed with hypertrophic osteopathy. The lungs showed diffuse parasitic granulomatous bronchointerstitial pneumonia caused by Halocercus delphini, consolidation of the pulmonary tissue, congestion, and alveolar edema. The animal was also afflicted by parasitic granulomatous gastritis caused by Anisakis simplex sensu lato and tattoo skin disease. The dolphin suffered from hypertrophic osteopathy associated with pulmonary Halocercus delphini infestation. This syndrome, known as hypertrophic pulmonary osteopathy, has been described in diverse terrestrial mammals, including domestic animals, wildlife and humans, but not in dolphins. This case reports the first description of hypertrophic osteopathy associated to a pulmonary disorder in dolphin, and it provides insights into factors that can induce column malformation in dolphins, suggesting the importance of taking thoracic lesions into account during differential diagnosis.

Case report: Sarcocystis speeri, Aspergillus fumigatus, and novel Treponema sp. infections in an adult Atlantic spotted dolphin (Stenella frontalis)

A complete postmortem examination, including a computed tomography scan “virtopsy” (virtual necropsy), gross necropsy, cytology, histology, and molecular diagnostics were performed to investigate the cause of death of a deceased adult male Atlantic spotted dolphin (Stenella frontalis) that stranded on Pensacola Beach, Florida, USA in February 2020. Significant findings included chronic inflammation of the meninges, brain, and spinal cord with intralesional protozoa (identified as Sarcocystis speeri via 18S rRNA and ITS-1 sequences), suppurative fungal tracheitis and bronchopneumonia (identified as Aspergillus fumigatus via ITS-2 gene sequence) and ulcerative bacterial glossitis (associated with a novel Treponema species, Candidatus Treponema stenella, identified via 23S rRNA gene sequence). This is the first reported case of S. speeri in a marine mammal. Little is understood about the epidemiology of S. speeri, including the identity of its intermediate hosts. The findings of this case suggest that S. frontalis may be a capable aberrant host and experience morbidity and mortality from this parasite. It is suspected that the novel Treponema and Aspergillus fumigatus infections were opportunistic or secondary to immunosuppression, either due to S. speeri infection or other co-morbidities.

Cerebral nasitremiasis in a Blainville's beaked whale (Mesoplodon densirostris) stranded in the Canary Islands

Ten species within the genus Nasitrema (subfamily Nasitrematinae, family Brachycladiidae) have been reported infecting a wide variety of odontocetes worldwide, although there is still a lack of information about their presence in beaked whales (BWs). Nasitrema spp. are commonly described inhabiting the pterygoid sinus, the tympanic cavities, and the middle and inner ear; although aberrant migrations through the brain have been also reported. This trematode may cause different type of lesions, ranging from mild to severe saculitis, neuritis, otitis, and/or meningoencephalitis that may impede cetaceans to survive in the wild, resulting in incoordination, loss of equilibrium, and echolocation dysfunction ending in a stranding event. The presence of Nasitrema sp. was found in an adult female Blainville beaked whale stranded death in Fuerteventura, Canary Islands, on November 2016. The most relevant gross finding was a severe chronic-active multifocal pyogranulomatous and necrotizing encephalitis. Histologically, multiple areas of necrosis, pyogranulomatous and eosinophilic inflammation, haemorrhages and occasional cholesterol crystals were found associated with parasitic structures compatible with an adult trematode and its eggs. Molecular analysis, based on a quantitative polymerase chain reaction (qPCR) of the brain tissue sample detected 99% homology with a partial sequence of the NADH dehydrogenase subunit 3 (ND3) gene of Nasitrema delphini. In addition, liver, kidney, prescapular lymph node and brain samples were positive to herpesvirus (conventional nested PCR). Evidence of the presence of this parasite was not found in any of the 54 beaked whales (n = 54) stranded on the Canary Islands between 1999 and 2017, specifically 35 Cuvier's BWs and 19 specimens belonging to the Mesoplodon genus. To our knowledge, the current study represents the first description of a nasitremiasis in a member of the Ziphiidae family.

An evolutionary medicine perspective on the cetacean pulmonary immune system - The first identification of SP-D and LBP in the bottlenose dolphin (Tursiops truncatus)

Evolutionary medicine expresses the present status of biomolecules affected by past evolutionary events. To clarify the whole picture of cetacean pneumonia, which is a major threat to cetaceans, their pulmonary immune system should be studied from the perspective of evolutionary medicine. In this in silico study, we focused on cetacean surfactant protein D (SP-D) and lipopolysaccharide-binding protein (LBP) as two representative molecules of the cetacean pulmonary immune system. Sequencing and analyzing SP-D and LBP in the bottlenose dolphin (Tursiops truncatus) lung and liver tissue collected post-mortem elucidated not only basic physicochemical properties but also their evolutionary background. This is the first study to report the sequences and expression of SP-D and LBP in the bottlenose dolphin. Besides, our findings also suggest the direction of an evolutionary arms race in the cetacean pulmonary immune system. These results have important positive implications for cetacean clinical medicine.

Fin Whale (Balaenoptera physalus) Mortality along the Italian Coast between 1624 and 2021

The Mediterranean Sea hosts a population of fin whale (Balaenoptera physalus), the only species of Mysticete regularly occurring in the basin. Observed and inferred mortality suggests that the population is likely declining. Accordingly, understanding the causes of mortality and assessing the health status is pivotal to the survival of this endangered population. While such studies are inherently difficult for a highly roaming species with a pelagic distribution, mortality events provide the opportunity to investigate biological and epidemiological traits linked to these events, and evaluate the footprint of human activity, especially when long-term data series exist. We present a comprehensive spatial-temporal overview of fin whale mortality events along the Italian coast encompassing four centuries (1624-2021). Time series analysis was used to highlight structural changes in the evolution of mortality through time, while spatial-temporal patterns in the distribution of mortality events were assessed through emerging hot spot analysis methods. Recent mortality events (1964-2021) were further explored to evaluate, where possible, the primary causes of mortality and to identify anthropogenic threats of conservation concerns. This long-term survey offers the basis for an understanding of the health status of this B. physalus population and provides much-needed information for developing an effective management and conservation plan for the species in the region.

Toothed Whales Have Black Neurons in the Blue Spot

Simple Summary

Neuromelanin is a dark pigment that is present in several types of neurons of the brain. The role of human neuromelanin is a matter of controversy and, over the past few years, has been attributed to having a dual nature, either in a protective role to shield neurons from toxic compounds, or as a trigger of neuroinflammation. This pigment has been researched mainly in the human brain, but it has also been found in the neurons of monkeys, horses, giraffes, cattle, sheep, goats, dogs, rats, and even in frogs and tadpoles. Even so, neuromelanin in humans and primates presents unique features that are not shown in other animals. A study on the morphology of the locus ceruleus (a key brain structure) of the family Delphinidae highlighted the presence of a large amount of neuromelanin within this brain area. In an attempt to better define the ultrastructure of neuromelanin in toothed whales, two brain specimens of the suborder Odontoceti were investigated. The two toothed whales that were examined presented melanin granules associated with lipid droplets and membranes that bore a striking resemblance with human neuromelanin. Its accumulation takes place over the entire life span, and appears to contain the story of one’s life exposure to several endogenous and environmental metals and/or compounds.

Abstract

Neuromelanin (NM) is a dark polymer pigment that is located mostly in the human substantia nigra, and in the locus ceruleus, referred to as “the blue spot”. NM increases linearly with age, and has been described mainly in the human brain; however, it also occurs in the neurons of monkeys, horses, giraffes, cattle, sheep, goats, dogs, rats, and even in frogs. While in most of these mammals NM shows the histochemical and ultrastructural features typical of lipofuscins, human NM is confined within cytoplasmic organelles that are surrounded by a double membrane, suggesting an autophagic origin. In a study on the morphology of the locus ceruleus of the family Delphinidae, the presence of a variable quantity of NM in the interior of locus ceruleus neurons was observed for the first time; meanwhile, nothing is known about its ultrastructure and composition. Transmission electron microscopy demonstrated in two toothed whales—an Atlantic spotted dolphin (Stenella frontalis; family Delphinidae) and a Blainville’s beaked whale (Mesoplodon densirostris; family Ziphiidae)—the presence of melanin granules associated with lipid droplets and membranes that were very similar to that of human NM. The relationship between NM and neuronal vulnerability must be studied in depth, and cetaceans may offer a new natural-spontaneous comparative model for the study of NM and its implication in neurodegenerative diseases.

Budd-Chiari-like pathology in dolphins

Nearly two decades ago, pathologic examination results suggested that acoustic factors, such as mid-frequency active naval military sonar (MFAS) could be the cause of acute decompression-like sickness in stranded beaked whales. Acute systemic gas embolism in these whales was reported together with enigmatic cystic liver lesions (CLL), characterized by intrahepatic encapsulated gas-filled cysts, tentatively interpreted as “gas-bubble” lesions in various other cetacean species. Here we provide a pathologic reinterpretation of CLL in odontocetes. Among 1,200 cetaceans necropsied, CLL were only observed in four striped dolphins (Stenella coeruleoalba), with a low prevalence (2%, N = 179). Together, our data strongly suggest that CLL are the result of the combination of a pre-existing or concomitant hepatic vascular disorder superimposed and exacerbated by gas bubbles, and clearly differ from acute systemic gas embolism in stranded beaked whales that is linked to MFAS. Budd-Chiari-like syndrome in dolphins is hypothesized based on the present pathologic findings. Nonetheless, further researched is warranted to determine precise etiopathogenesis(es) and contributing factors for CLL in cetaceans.

Evaluating Potential Cetacean Welfare Indicators from Video of Live Stranded Long-Finned Pilot Whales (Globicephala melas edwardii)

Despite the known benefit of considering welfare within wildlife conservation and management, there remains a lack of data to inform such evaluations. To assess animal welfare, relevant information must be captured scientifically and systematically. A key first step is identifying potential indicators of welfare and the practicality of their measurement. We assessed the feasibility of evaluating potential welfare indicators from opportunistically gathered video footage of four stranded odontocete species (n = 53) at 14 stranding events around New Zealand. The first stranded cetacean ethogram was compiled, including 30 different behaviours, 20 of which were observed in all four species. Additionally, thirteen types of human intervention were classified. A subset of 49 live stranded long-finned pilot whales (Globicephala melas edwardii) were assessed to determine indicator prevalence and to quantify behaviours. Four ‘welfare status’ and six ‘welfare alerting’ non-behavioural indicators could be consistently evaluated from the footage. Additionally, two composite behavioural indicators were feasible. Three human intervention types (present, watering, and touching) and five animal behaviours (tail flutter, dorsal fin flutter, head lift, tail lift, and head side-to-side) were prevalent (>40% of individuals). Our study highlights the potential for non-invasive, remote assessments via video footage and represents an initial step towards developing a systematic, holistic welfare assessment framework for stranded cetaceans.

Systematic validation and assessment of immunohistochemical markers for central nervous system pathology in cetaceans, with emphasis on auditory pathways

Cetacean neuropathology is a developing field that aims to assess structural and neurochemical changes involved in neurodegenerative, infectious and traumatic processes, however markers used previously in cetaceans have rarely undergone systematic validation. This is a prerequisite to investigating the potential damage inflicted on the cetacean auditory system by anthropogenic noise. In order to assess apoptotic, neuroinflammatory and structural aberrations on a protein level, the baseline expression of biomarker proteins has to be characterized, implementing a systematic approach to validate the use of anti-human and anti-laboratory animal antibodies in dolphin tissues. This approach was taken to study 12 different antibodies associated with hypoxic-ischemic, inflammatory, plastic and excitatory-inhibitory changes implicated in acoustic trauma within the ventral cochlear nuclei and inferior colliculi of 20 bottlenose dolphins (Tursiops truncatus). Out of the 12 tested antibodies, pro-apoptotic protease factor 1 (Apaf-1), diacylglycerolkinase-ζ (DGK-ζ), B-cell lymphoma related protein 2 (Bcl-2), amyloid-β peptide (Aβ) and neurofilament 200 (NF200) were validated employing Western blot analyses and immunohistochemistry (IHC). The results of the validation process indicate specific patterns of immunoreactivity that are comparable to those reported in other mammals, thus suggesting a key panel of IHC biomarkers of pathological processes in the cetacean brain. As a consequence, the antibodies tested in this study may constitute a valid tool for supporting existing diagnostic methods in neurological diseases. The approach of systematic validation of IHC markers in cetaceans is proposed as a standard practice, in order for results to be transparent, reliable and comparable.

INVESTIGATION OF THE USE OF SERUM BIOMARKERS FOR THE DETECTION OF CARDIAC DISEASE IN MARINE MAMMALS

Cardiac disease has been extensively documented in marine mammals; however, it remains difficult to diagnose antemortem. Assays measuring cardiac troponin I (cTnI) and N-terminal pro-brain natriuretic peptide (NT-proBNP) are used as sensitive and specific biomarkers of cardiac disease in many species, but have not been widely investigated in marine mammals. This study aimed to provide a set of reference values for cTnI and NT-proBNP in belugas (BW) (Delphinapterus leucas), sea otters (SO) (Enhydra lutris), Steller sea lions (SSL) (Eumetopias jubatus), and California sea lions (CSL) (Zalophus californianus) with and without cardiac disease, and to determine if these biomarkers are useful indicators of cardiac disease in these species. First, existing immunoassays for cTnI and NT-proBNP were successfully validated utilizing species-specific heart lysate spiked serum. Cohorts were defined by histopathology as animals with no evidence of cardiac disease ("control"), with confirmed cardiac disease ("disease"), and with concurrent renal and cardiac disease ("renal") for which serum samples were then analyzed. Serum concentration ranges for cTnI (ng/ml) and NT-proBNP (pmol/L) were determined for control and disease cohorts. There was significantly higher cTnI (P= 0.003) and NT-proBNP (P= 0.004) concentrations in the CSL disease cohort, as well as positive trends in BW, SO, and SSL disease cohorts that did not reach statistical significance. NT-proBNP concentrations were significantly higher in the CSL renal cohort compared with the control (P < 0.001) and disease (P= 0.007) cohorts. These results suggest that cTnI and NT-proBNP may be clinically useful in the antemortem diagnosis of cardiac disease in CSL, and warrant further investigation in BW, SO, and SL.

The impact of marine debris on cetaceans with consideration of plastics generated by the COVID-19 pandemic

The accumulation of human-derived debris in the oceans is a global concern and a serious threat to marine wildlife. There is a volume of evidence that points to deleterious effects of marine debris (MD) on cetaceans in terms of both entanglement and ingestion. This review suggests that about 68% of cetacean species are affected by interacting with MD with an increase in the number of species reported to have interacted with it over the past decades. Despite the growing body of evidence, there is an ongoing debate on the actual effects of plastics on cetaceans and, in particular, with reference to the ingestion of microplastics and their potential toxicological and pathogenic effects. Current knowledge suggests that the observed differences in the rate and nature of interactions with plastics are the result of substantial differences in species-specific diving and feeding strategies. Existing projections on the production, use and disposal of plastics suggest a further increase of marine plastic pollution. In this context, the contribution of the ongoing COVID-19 pandemic to marine plastic pollution appears to be substantial, with potentially serious consequences for marine life including cetaceans. Additionally, the COVID-19 pandemic offers an opportunity to investigate the direct links between industry, human behaviours and the effects of MD on cetaceans. This could help inform management, prevention efforts, describe knowledge gaps and guide advancements in research efforts. This review highlights the lack of assessments of population-level effects related to MD and suggests that these could be rather immediate for small populations already under pressure from other anthropogenic activities. Finally, we suggest that MD is not only a pollution, economic and social issue, but also a welfare concern for the species and populations involved.

Molecular Characterization of Herpesviral Encephalitis in Cetaceans: Correlation with Histopathological and Immunohistochemical Findings

Simple Summary

In this study we describe the molecular and pathological characteristics of alpha- and gamma-herpesvirus infection of the central nervous system of stranded cetaceans and correlate them with viral load, immunohistochemical findings and biological data such as age, sex, and the presence of co-infections. The viruses (alpha- and gamma-herpesvirus) were detected in twelve out of 103 analysed stranded cetaceans and were associated with a wide range of histopathological lesions, as previously described for these and other species. In five out the twelve animals, lesions were severe enough (malacia, neuronal necrosis and neuronophagia) to cause death. Intranuclear inclusions bodies were present in brain tissue samples from half of the HV-positive animals, indicating that the injury was due to an infective agent belonging to a group of filterable viruses. These results are in accordance with immunohistochemical findings, as all the brain tissue samples with INIBs were immunolabeled with Anti-HSV1. Males, juveniles, and calves were predominantly infected among the analysed cetaceans and a 41.6% (5/12) incidence of co-infections in the brain was detected, with three animals co-infected with Dolphin Morbillivirus (DMV). In this study, we present, to the best of our knowledge, the first histopathological evidence of superinfection between HV and DMV pathogens in brain tissue.

Abstract

Herpesviruses are causative agents of meningitis and encephalitis in cetaceans, which are among the main leading known natural causes of death in these species. Brain samples from 103 stranded cetaceans were retrospectively screened for the presence of herpesvirus DNA in the brain. Molecular detection of Cetacean Morbillivirus was performed in HV positive brain cases. Histopathologic evaluation of brain samples included the presence or absence of the following findings (n = 7): meningitis, perivascular cuffings, microgliosis, intranuclear inclusion bodies, malacia, neuronal necrosis and neurophagic nodules, and haemorrhages. Histological evidence of the involvement of other etiological agents led to complementary analysis. We detected the presence of alpha and gamma-HVs in 12 out of 103 (11.6%) brain samples from stranded cetaceans of five different species: one bottlenose dolphin, six striped dolphins, three Atlantic spotted dolphins, one Cuvier’s beaked whale, and one common dolphin. Pathogenic factors such as viral strain, age, sex, and the presence of co-infections were analysed and correlated with the brain histopathological findings in each case. Herpesvirus was more prevalent in males, juveniles, and calves and a 41.6% incidence of co-infections in the brain was detected in our study: three with Dolphin Morbillivirus, one with Staphilococcus aureus septicaemia and one with Brucella spp.

Fundamental Concepts, Knowledge Gaps and Key Concerns Relating to Welfare and Survival of Stranded Cetaceans

Wildlife management can influence animal welfare and survival, although both are often not explicitly integrated into decision making. This study explores fundamental concepts and key concerns relating to the welfare and survival of stranded cetaceans. Using the Delphi method, the opinions of an international, interdisciplinary expert panel were gathered, regarding the characterisation of stranded cetacean welfare and survival likelihood, knowledge gaps and key concerns. Experts suggest that stranded cetacean welfare should be characterised based on interrelated aspects of animals’ biological function, behaviour, and mental state and the impacts of human interventions. The characterisation of survival likelihood should reflect aspects of stranded animals’ biological functioning and behaviour as well as a 6-month post-re-floating survival marker. Post-release monitoring was the major knowledge gap for survival. Welfare knowledge gaps related to diagnosing internal injuries, interpreting behavioural and physiological parameters, and euthanasia decision making. Twelve concerns were highlighted for both welfare and survival likelihood, including difficulty breathing and organ compression, skin damage and physical traumas, separation from conspecifics, and suffering and stress due to stranding and human intervention. These findings indicate inextricable links between perceptions of welfare state and the likely survival of stranded cetaceans and demonstrate a need to integrate welfare science alongside conservation biology to achieve effective, ethical management at strandings.

Microscopic Findings in the Cardiac Muscle of Stranded Extreme Deep-Diving Cuvier's Beaked Whales (Ziphius cavirostris)

Considerable information has been gained over the last few decades on several disease processes afflicting free-ranging cetaceans from a pathologist's point of view. Nonetheless, there is still a dearth of studies on the hearts of these species. For this reason, we aimed to improve our understanding of cardiac histological lesions occurring in free-ranging stranded cetaceans and, more specifically, in deep-diving Cuvier's beaked whales. The primary cardiac lesions that have been described include vascular changes, such as congestion, edema, hemorrhage, leukocytosis, and intravascular coagulation; acute degenerative changes, which consist of contraction band necrosis, wavy fibers, cytoplasmic hypereosinophilia, and perinuclear vacuolization; infiltration of inflammatory cells; and finally, the presence and/or deposition of different substances, such as interstitial myoglobin globules, lipofuscin pigment, polysaccharide complexes, and intra- and/or extravascular gas emboli and vessel dilation. This study advances our current knowledge about the histopathological findings in the cardiac muscle of cetaceans, and more specifically, of Cuvier's beaked whales.

Establishment of a fish model to study gas-bubble lesions

Decompression sickness (DCS) is a clinical syndrome caused by the formation of systemic intravascular and extravascular gas bubbles. The presence of these bubbles in blood vessels is known as gas embolism. DCS has been described in humans and animals such as sea turtles and cetaceans. To delve deeper into DCS, experimental models in terrestrial mammals subjected to compression/decompression in a hyperbaric chamber have been used. Fish can suffer from gas bubble disease (GBD), characterized by the formation of intravascular and extravascular systemic gas bubbles, similarly to that observed in DCS. Given these similarities and the fact that fish develop this disease naturally in supersaturated water, they could be used as an alternative experimental model for the study of the pathophysiological aspect of gas bubbles. The objective of this study was to obtain a reproducible model for GBD in fish by an engineering system and a complete pathological study, validating this model for the study of the physiopathology of gas related lesions in DCS. A massive and severe GBD was achieved by exposing the fish for 18 h to TDG values of 162-163%, characterized by the presence of severe hemorrhages and the visualization of massive quantities of macroscopic and microscopic gas bubbles, systemically distributed, circulating through different large vessels of experimental fish. These pathological findings were the same as those described in small mammals for the study of explosive DCS by hyperbaric chamber, validating the translational usefulness of this first fish model to study the gas-bubbles lesions associated to DCS from a pathological standpoint.

Molecular Diagnosis of Cetacean Morbillivirus in Beaked Whales Stranded in the Canary Islands (1999–2017)

A retrospective survey for detecting the cetacean morbillivirus (CeMV) was carried out in beaked whales (BWs) stranded in the Canary Islands (1999–2017). CeMV is responsible for causing worldwide epizootic events with the highest mass die-offs in cetaceans, although the epidemic status of the Canarian Archipelago seems to be that of an endemic situation. A total of 319 tissue samples from 55 BWs (35 Cuvier’s BWs and 20 specimens belonging to the Mesoplodon genus) were subjected to the amplification of a fragment of the fusion protein (F) and/or phosphoprotein (P) genes of CeMV by means of one or more of three polymerase chain reactions (PCR). RNA integrity could not be demonstrated in samples from 11 animals. Positivity (dolphin morbillivirus strain (DMV)) was detected in the skin sample of only a subadult male Cuvier’s BW stranded in 2002, being the earliest confirmed occurrence of DMV in the Cuvier’s BW species. The obtained P gene sequence showed the closest relationship with other DMVs detected in a striped dolphin stranded in the Canary Islands in the same year. A phylogenetic analysis supports a previous hypothesis of a cross-species infection and the existence of the circulation of endemic DMV strains in the Atlantic Ocean similar to those later detected in the North-East Atlantic, the Mediterranean Sea and the South-West Pacific.

Pulmonary and Systemic Skeletal Muscle Embolism in a Beaked Whale with a Massive Trauma of Unknown Aetiology

Simple Summary

A severe trauma of unknown aetiology was suspected as the cause of death in an adult female Sowerby’s beaked whale found floating dead in the Canary Islands in December 2016. Many bruises in the skin and muscles (contusions) were observed in the chest wall and bone fractures, mainly located in the mandible and ribs. The broken rib bones also affected thoracic muscles, which escaped into the blood circulation once ruptured, reaching several organic locations, including the lungs, where they became trapped within the small lumen of pulmonary blood vessels, leading to a systemic and pulmonary skeletal muscle embolism. An embolism occurs when a piece of intravascular internal or foreign material obstructs the lumen of a blood vessel, starving tissues of blood and oxygen. An embolism necessarily needs cardiac function, indicating a survival time after trauma. This case report aimed to include the diagnosis of skeletal muscle embolism as a routine tool to determine if the traumatic event occurred before or after death. This is especially valuable when working with dead animals because no other evidence of traumatic injury may be recorded if carcasses are in advanced decay.

Abstract

An adult female Sowerby’s beaked whale was found floating dead in Hermigua (La Gomera, Canary Islands, Spain) on 7 December 2016. Severe traumas of unknown aetiology were attributed, and the gross and microscopic findings are consistent with catastrophic trauma as a cause of death. Rib fractures affected the intercostals, transverse thoracis skeletal muscles, and thoracic rete mirabile. Degenerated muscle fibres were extruded to flow into vascular and lymphatic vessels travelling to several anatomic locations into the thoracic cavity, including the lungs, where they occluded the small lumen of pulmonary microvasculature. A pulmonary and systemic skeletal muscle embolism was diagnosed, constituting the first description of this kind of embolism in an animal. The only previous description has been reported in a woman after peritoneal dialysis. Skeletal pulmonary embolism should be considered a valuable diagnostic for different types of trauma in vivo in wild animals. This is especially valuable when working with decomposed carcasses, as in those cases, it is not always feasible to assess other traumatic evidence.

Nocardiosis in Free-Ranging Cetaceans from the Central-Eastern Atlantic Ocean and Contiguous Mediterranean Sea

Simple Summary

Characterization, description, and geographical location of harmful bacterial agents in cetaceans are important for population surveillance and health monitoring around the world. This research compiles the pathologic features of nocardiosis in five free-ranging delphinids from the Canary Islands and Andalusia. All examined animals showed a disseminated pattern of infection with characteristic suppurative to pyogranulomatous lesions with thromboembolism in two or more organs. The obtained results provide the first record of N. otitidiscaviarum in cetaceans, the first account of N. farcinica in free-ranging dolphins, and confirmation of nocardiosis in central eastern Atlantic Ocean.

Abstract

We report the pathologic features of nocardiosis in five free-ranging delphinids from the Canary Islands and Andalusia, namely four striped dolphins (Stenella coerulealba) and one bottlenose dolphin (Tursiops truncatus). All animals had a multiorgan (disseminated) pattern of infection involving suppurative to pyogranulomatous and thromboembolic lesions in two or more organs. Most affected organs were (by decreasing order) lung, pulmonary lymph nodes, liver, kidney, adrenal glands, and central nervous system. Typical intralesional and intravascular branched and filamentous bacteria were highlighted by Grocott’s methenamine silver and Gram stains. Bacterial analysis including 16S rRNA gene sequencing identified Nocardia farcinica in two striped dolphins and Nocardia otitidiscaviarum in one striped dolphin and the bottlenose dolphin. All dolphins tested (n = 4) for cetacean morbillivirus were negative; one dolphin had concurrent cutaneous herpesvirosis. These results provide the first record of N. otitidiscaviarum in cetaceans, the first account of N. farcinica in free-ranging dolphins, and confirmation of nocardiosis in central eastern Atlantic Ocean. These results expand the known geographic range of nocardiosis in cetaceans.

Microplastics, bisphenols, phthalates and pesticides in odontocete species in the Macaronesian Region (Eastern North Atlantic)

The gastrointestinal contents of twelve individuals from six odontocete species that stranded between 2018 and 2019 in the Macaronesian Region (Eastern North Atlantic) were examined for the presence of marine debris. In addition, concentrations of eleven organic persistent contaminants (nonylphenols, bisphenols, phthalates and pesticides) were analysed in muscle samples by liquid chromatography. No particles larger than 5 mm were found, except for two plastic labels that were found on the same dolphin. On the contrary, all animals contained microplastics of diverse sizes, most of them being fibres (98.06%, n = 708). The predominant detected pollutants were bisphenols (4-984 ng/g) and DEHP (102-1533 ng/g). Also, except for two individuals, all animals had pesticide levels in their tissues. This work has allowed the establishment of a protocol for the study of microplastic ingestion in cetaceans, and tests the potential of microRaman to improve the understanding of microplastic alteration processes.

Crassicaudiasis in three geographically and chronologically distant Cuvier's beaked whales (Ziphius cavirostris) stranded off Brazil

The Cuvier's beaked whale (CBW; Ziphius cavirostris) is a cosmopolitan marine mammal found in deep tropical and temperate waters of all oceans. CBW strandings have been recorded sporadically in Brazil; however, there is lack of information available regarding their causes of stranding and/or death. Herein, we report the epidemiologic, pathologic, morphologic parasitologic features and molecular identification of arterial and renal crassicaudiasis by Crassicauda sp. in three geographically and chronologically distant CBW stranded off Brazil. CBW-1 was an adult male stranded dead in Rio Grande do Sul State. CBW-2 was an adult female that stranded alive in Sergipe State and died shortly after. CBW-3 was and adult male that stranded dead in Santa Catarina State. The most relevant pathologic findings in these three CBW were severe, chronic proliferative mesenteric and caudal aortic endarteritis and chronic granulomatous and fibrosing interstitial nephritis with renicular atrophy and loss, and numerous intralesional Crassicauda sp. nematodes. Furthermore, CBW-1 had concomitant gram-negative bacterial pneumonia and pulmonary and hepatic thromboembolism. Morphologic analysis of renal adult nematodes identified Crassicauda sp. in the three CBW. Molecular analyses targeting the 18S and ITS-2 ribosomal loci of renal nematodes in CBW-2 and CBW-3 identified C. anthonyi. It is believed that severe arterial and renal crassicaudiasis likely resulted or contributed significantly to morbidity and death of these animals. These results expand the known geographical range of occurrence of crassicaudiasis in CBW. Specifically, the present study provides the first accounts of arterial and renal crassicaudiasis in CBW off the southern hemisphere, specifically in CBW off Brazil, and to the authors' knowledge, it is the first record of C. anthonyi in the southern Atlantic Ocean.

•

First record of Crassicauda anthonyi in cetaceans off the southern Atlantic Ocean.

•

Arterial and renal crassicaudiasis may be fatal in Ziphius cavirostris.

•

ITS-2 gene sequence analysis enables Crassicauda species identification.

Bacteriological and histopathological findings in cetaceans that stranded in the Philippines from 2017 to 2018

The relatively high frequency of marine mammal stranding events in the Philippines provide many research opportunities. A select set of stranders (n = 21) from 2017 to 2018 were sampled for bacteriology and histopathology. Pertinent tissues and bacteria were collected from individuals representing eight cetacean species (i.e. Feresa attenuata, Kogia breviceps, Globicephala macrorhynchus, Grampus griseus, Lagenodelphis hosei, Peponocephala electra, Stenella attenuata and Stenella longirostris) and were subjected to histopathological examination and antibiotic resistance screening, respectively. The antibiotic resistance profiles of 24 bacteria (belonging to genera Escherichia, Enterobacter, Klebsiella, Proteus, and Shigella) that were isolated from four cetaceans were determined using 18 antibiotics. All 24 isolates were resistant to at least one antibiotic class, and 79.17% were classified as multiple antibiotic resistant (MAR). The MAR index values of isolates ranged from 0.06 to 0.39 with all the isolates resistant to erythromycin (100%; n = 24) and susceptible to imipenem, doripenem, ciprofloxacin, chloramphenicol, and gentamicin (100%; n = 24). The resistance profiles of these bacteria show the extent of antimicrobial resistance in the marine environment, and may inform medical management decisions during rehabilitation of stranded cetaceans. Due to inadequate gross descriptions and limited data gathered by the responders during the stranding events, the significance of histopathological lesions in association with disease diagnosis in each cetacean stranding or mortality remained inconclusive; however, these histopathological findings may be indicative or contributory to the resulting debility and stress during their strandings. The findings of the study demonstrate the challenges faced by cetacean species in the wild, such as but not limited to, biological pollution through land-sea movement of effluents, fisheries interactions, and anthropogenic activities.

The Validation of a Non-Invasive Skin Sampling Device for Detecting Cetacean Poxvirus

Simple Summary

The current growing social awareness of animal welfare has led to the development of welfare indicators, which are effective tools for assessing each of the integrated aspects of this multidisciplinary issue. Hence, skin diseases have been suggested as potential general health indicators for use in cetaceans. Particularly cetacean poxvirus causes distinguishable hyperpigmented “ring” or “tattoo” lesions that affect cetaceans both in the wild and in managed facilities. However, most studies have analyzed these characteristic lesions through visual appraisal, while only a few have implemented diagnostic methods to corroborate the presence of the virus. To this end, skin biopsies are usually the sampling method selected, although they are considered to be an intrusive procedure. In this study, we analyzed sloughed skin sampled with cytology cell samplers (CCSs) in 12 tattoo-like lesions from two free-ranging cetaceans stranded in the Canary Islands. We employed two different DNA extraction methods and compared the effectiveness of the device with that of biopsies. All the lesions resulted positive for cetacean poxvirus, obtaining reliable data from the use of this device. Thus, CCS is considered to be a promising non-invasive tool for further assessing skin diseases in cetaceans, particularly those under human care, without affecting their welfare.

Abstract

Poxvirus-like lesions are widely used as a potential health indicator in cetaceans, although for this application, corroboration of Poxvirus skin disease is imperative. Aiming to address skin biopsies intrusiveness, a preliminary investigation of a non-invasive skin sampling procedure to molecularly detect CePV-1 in 12 tattoo-like-lesions from two free-ranging stranded cetaceans in the Canary Islands was performed. Skin lesions were brushed with cytology cell samplers (CCSs) and placed into 1.5 mL microcentrifuge tubes with 1 mL of RNAlater^TM Stabilization Solution. For factual comparisons, DNA extractions from sloughed skin obtained with CCS and biopsies from the same lesions were accomplished with DNA Tissue Kit S^TM (QuickGene, Kurabo, Japan). Moreover, a second DNA extraction from sloughed skin with DNeasy^TM Blood and Tissue Kit (Qiagen, Inc., Valencia, CA, USA) was performed to ascertain kit suitability for CCS. Molecular detection of CePV-1 was performed through a real-time PCR. As a result, a 91.7% and 83.3% rates of positivity were obtained with biopsies and CCS through Quickgene, respectively, compared to the rate of 100% using CCS with Qiagen. Accordingly, CCS is a reliable non-invasive sampling device to obtain sufficient genetic material to be analyzed for CePV-1 in tattoo-skin-lesions as well as for other purposes in cetaceans under human care.

TOTAL EAR CANAL ABLATION AND LATERAL BULLA OSTEOTOMY (TECA-LBO) IN ATLANTIC HARBOR SEALS (PHOCA VITULINA CONCOLOR) FOR SUCCESSFUL SURGICAL MANAGEMENT OF OTITIS MEDIA

Chronic, severe otitis media was diagnosed in four Atlantic harbor seals (Phoca vitulina concolor), three of which were stranded animals undergoing rehabilitation. All seals presented with unilateral purulent aural discharge that would intermittently recur despite prolonged topical and systemic antimicrobial therapy. Aerobic culture from aural discharge isolated multidrug-resistant organisms in all seals, including Pseudomonas aeruginosa, Staphylococcus pseudintermedius, Klebsiella pneumoniae, and/or Enterococcus faecalis. Computed tomography was used in three cases to confirm otitis media and positive contrast ear canalography was used in one case to confirm tympanic membrane rupture. Given the persistent nature of otitis, surgical intervention in the form of a total ear canal ablation and lateral bulla osteotomy (TECA-LBO) was indicated. Surgery was successful in achieving complete clinical resolution of otitis in all seals. Postoperative complications included temporary unilateral paralysis of the left nare (2/4) and a transient left ptosis (1/4). Partial to complete surgical site dehiscence occurred in all cases; however, complete healing was achieved by second intention in 60 d or less. One rehabilitated seal was fitted with a satellite tag that confirmed normal swimming and diving patterns post release. In harbor seals, TECA-LBO can be performed safely to treat persistent cases of otitis media and should be considered in cases of chronic otitis that are not responsive to medical management.

Analysis of the Gastro-Intestinal Tract of Marine Mammals: A Multidisciplinary Approach with a New Multi-Sieves Tool

Simple Summary

Currently procedures used to obtain samples from the gastro-intestinal tract (GIT) and protocols used to perform their respective analyses do not allow a multidisciplinary approach of this system. In fact, the investigations applied on the GIT, when performed singularly, could impair or limit the other analyses, because the currently procedures do not consider the needs of other disciplines. This means that the analyses to perform must be selected a priori, sacrificing the collection of other types of data and leads to the risk of losing important information, especially for wildlife species. To solve this conflict, we implement and standardize a new methodological approach to the GIT of marine mammals, which allow the collection of samples for different disciplines at the same time, performing the respective analyses, interpret and compare their results in a multidisciplinary way. The compatibility of multiple analyses allows the gaining of more information about the cause of death of stranded marine mammals and to enhance the knowledge of their biology and ecology.

Abstract

Organs and content of the gastro-intestinal tract (GIT) of marine mammals are relevant for a variety of investigations and provide data to researchers from different fields. Currently used protocols applied to the GIT for specific analysis limit the possibility to execute other investigations and important information could be lost. To ensure a proper sample collection and a multidisciplinary investigation of the GIT of marine mammals, a new multi-sieves tool and a specific protocol have been developed. This new device and approach allowed the simultaneous sampling of the GIT and its content for the main investigations concerned. The samples collected during these preliminary trials were suitable to perform all the different research procedures considered in this work. The obtained results show that with a few and easy procedural adjustments, a multidisciplinary sampling and evaluation of the GIT of marine mammals is possible. This will reduce the risk of losing important data aimed at understanding the cause of death of the animal, but also biology and ecology of marine mammals, and other important data for their conservation and habitats management.

Diseases and parasites

Inuit in Alaska, Canada, and Russia have a long-term tradition in hunting bowhead whales that reaches back several thousands of years. Central to Inuit culture, hunted bowhead whales have undergone rigorous health evaluation by hunters and communities through various iterative processes guided by traditional customary practices. These traditional customary practices are similar to western meat hygiene designed to provide a thorough health assessment of the catch and by default, a public health judgment on food safety. With the establishment of the bowhead whale harvest monitoring program in Utqiaġvik in 1972, led by the North Slope Borough leadership and Alaska Eskimo Whaling Commission (AEWC), collaborative research on the health of bowhead whales between the AEWC, Village Whaling Captains Association, Whaling Captain’s Wives Association, research scientists, and veterinarians have continued to build on the in-depth Inuit knowledge of the bowhead whale. This chapter synthesizes the historic and current knowledge about health and disease conditions of the bowhead whale. The information provided is a coproduction of knowledge reflecting perspectives of Inuit indigenous and local knowledge, veterinary medicine, and biology.

Retrospective Study of Fishery Interactions in Stranded Cetaceans, Canary Islands

Estimating cetacean interactions with fishery activities is challenging. Bycatch and chronic entanglements are responsible for thousands of cetacean deaths per year globally. This study represents the first systematic approach to the postmortem investigation of fishery interactions in stranded cetaceans in the Canary Islands. We retrospectively studied 586 cases necropsied between January 2000 and December 2018. Of the cases with a known cause of death, 7.4% (32/453) were due to fishery interactions, and the Atlantic spotted dolphin (Stenella frontalis) was the most affected species [46.9% (15/32)]. Three types of fishery interactions were recognized by gross findings: bycatch [65.6% (21/32)], chronic entanglements [18.8% (6/32)], and fishermen aggression [15.6% (5/32)]. Among the bycaught cases, we differentiated the dolphins that died because of ingestion of longline hooks [23.8% (5/21)] from those that died because of fishing net entrapments [76.2% (16/21)], including dolphins that presumably died at depth due to peracute underwater entrapment (PUE) [37.5% (6/16)], dolphins that were hauled out alive and suffered additional trauma during handling [43.8% (7/16)], and those that were released alive but became stranded and died because of fishery interactions [18.7% (3/16)]. Gross and histologic findings of animals in each group were presented and compared. The histological approach confirmed gross lesions and excluded other possible causes of death. Cetaceans in good-fair body condition and shallow diving species were significantly more affected by fishery interactions, in agreement with the literature. Low rates of fishery interactions have been described, compared with other regions. However, within the last few years, sightings of entangled live whales, especially the minke whale (Balaenoptera acutorostrata) and Bryde's whale (B. edeni), have increased. This study contributes to further improvement of the evaluation of different types of fishery interactions and may facilitate the enforcement of future conservation policies to preserve cetacean populations in the Canary Islands.

Histopathological Differential Diagnosis of Meningoencephalitis in Cetaceans: Morbillivirus, Herpesvirus, Toxoplasma gondii, Brucella sp., and Nasitrema sp

Infectious and inflammatory processes are among the most common causes of central nervous system involvement in stranded cetaceans. Meningitis and encephalitis are among the leading known natural causes of death in stranded cetaceans and may be caused by a wide range of pathogens. This study describes histopathological findings in post-mortem brain tissue specimens from stranded cetaceans associated with five relevant infectious agents: viruses [Cetacean Morbillivirus (CeMV) and Herpesvirus (HV); n = 29], bacteria (Brucella sp.; n = 7), protozoa (Toxoplasma gondii; n = 6), and helminths (Nasitrema sp.; n = 1). Aetiological diagnosis was established by molecular methods. Histopathologic evaluations of brain samples were performed in all the cases, and additional histochemical and/or immunohistochemical stains were carried out accordingly. Compared with those produced by other types of pathogens in our study, the characteristic features of viral meningoencephalitis (CeMV and HV) included the most severe and frequent presence of malacia, intranuclear, and/or intracytoplasmic inclusion bodies, neuronal necrosis and associated neuronophagia, syncytia and hemorrhages, predominantly in the cerebrum. The characteristic features of Brucella sp. meningoencephalitis included the most severe and frequent presence of meningitis, perivascular cuffing, cerebellitis, myelitis, polyradiculoneuritis, choroiditis, ventriculitis, vasculitis, and fibrinoid necrosis of vessels. The characteristic features of T. gondii meningoencephalitis included lymphocytic and granulomatous encephalitis, tissue cysts, microgliosis, and oedema. In the case of Nasitrema sp. infection, lesions are all that we describe since just one animal was available. The results of this study are expected to contribute, to a large extent, to a better understanding of brain-pathogen-associated lesions in cetaceans.

Lipids of lung and lung fat emboli of the toothed whales (Odontoceti)

Lipids are biomolecules present in all living organisms that, apart from their physiological functions, can be involved in different pathologies. One of these pathologies is fat embolism, which has been described histologically in the lung of cetaceans in association with ship strikes and with gas and fat embolic syndrome. To assess pathological lung lipid composition, previous knowledge of healthy lung tissue lipid composition is essential; however, these studies are extremely scarce in cetaceans. In the present study we aimed first, to characterize the lipids ordinarily present in the lung tissue of seven cetacean species; and second, to better understand the etiopathogenesis of fat embolism by comparing the lipid composition of lungs positive for fat emboli, and those negative for emboli in Physeter macrocephalus and Ziphius cavirostris (two species in which fat emboli have been described). Results showed that lipid content and lipid classes did not differ among species or diving profiles. In contrast, fatty acid composition was significantly different between species, with C16:0 and C18:1ω9 explaining most of the differences. This baseline knowledge of healthy lung tissue lipid composition will be extremely useful in future studies assessing lung pathologies involving lipids. Concerning fat embolism, non-significant differences could be established between lipid content, lipid classes, and fatty acid composition. However, an unidentified peak was only found in the chromatogram for the two struck whales and merits further investigation.

Dolphins Stranded along the Tuscan Coastline (Central Italy) of the "Pelagos Sanctuary": A Parasitological Investigation

Parasite monitoring is considered a necessary step for cetacean management and conservation. Between February 2013 and July 2015, 26 dolphins (15 Stenella coeruleoalba, 10 Tursiops truncatus, and one Grampus griseus) stranded along the Tuscan coastline of the protected marine area "Pelagos Sanctuary", were examined. Organs, tissues, and faecal and blood samples taken from all animals were analysed by parasitological, immunological, and molecular techniques. Twenty-one out of 26 dolphins (80.77%) tested positive for at least one parasite species, and 13/15 (86.7%) S. coeruleoalba, 7/10 (70%) T. truncatus, and the single G. griseus were found positive. Identified parasites included the nematodes Skrjabinalius guevarai (7.69%, 2/26), Halocercus lagenorhynchi (3.85%, 1/26), Halocercus delphini (7.69%, 2/26), Stenurus ovatus (7.69%, 2/26), Crassicauda spp. (7.69%, 2/26); the trematodes Pholeter gastrophilus (26.92%, 7/26), Campula palliata (3.85%, 1/26); the cestodes Phyllobothrium delphini (42.31%, 11/26), Monorygma grimaldii (23.08%, 6/26), Tetrabothrium forsteri (7.69%, 2/26), Strobilocephalus triangularis (7.69%, 2/26), and the acanthocephalan Bolbosoma vasculosum (7.69%, 2/26). Moreover, 6/26 (23%) animals scored positive to Toxoplasma gondii at serology, but PCR confirmed the infection (T. gondii Type II genotype) in a single animal. In examined dolphins, obtained results showed a high prevalence of endoparasites, which included species considered as a cause of severe debilitation or death.

Histochemical and Immunohistochemical Characterizations of Hepatic Trematodiasis in Odontocetes

Hepatic trematodiasis is a common condition in a number of free-ranging cetacean species, which occasionally result in severe hepatic and/or pancreatic lesions. However, even the basic pathological information of this disease is unknown for the majority of affected species. The current study describes and compares the histomorphology and immune reaction induced by hepatic trematodes of the family Brachycladiidae in the liver of the harbor porpoise (Phocoena phocoena, n = 8), Dall's porpoise (Phocoenoides dalli, n = 8), and Hubbs' beaked whale (Mesoplodon carlhubbsi, n = 2). Immunohistochemistry for eight antibodies (CK19, CD3, Foxp3, CD20, Iba1, CD68, CD163, and CD204) was conducted to analyze the pathology of these parasitic infections. In all three odontocete species, the changes observed in the trematode-affected biliary epithelium were comparable with marked hyperplasia and goblet cell metaplasia, as well as lymphoplasmacytic and eosinophilic inflammation. Additionally, regions of the Glisson's sheath were diffusely and severely fibrotic in all examined species, regardless of the physical presence of trematodes. Differences among the three species included the presence of characteristic lymphoid follicles formed in the fibrotic bile duct walls of only the two porpoise species. In the Hubbs' beaked whale, the degree of lymphoplasmacytic cholangitis was more severe, and ductular reaction was generally more prominent. In terms of the overall macrophage population among the three species, CD163- and CD204-positive cells (M2 macrophages) outnumbered Iba1- and CD68-positive cells (M1 macrophages), indicating a chronic infection stage in all analyzed individuals. Species-specific differences among the infiltrating macrophages included numbers of CD68-positive cells being significantly more abundant in the harbor porpoises, whereas CD163-positive cells were significantly more numerous in the Dall's porpoises. The numbers of CD204-positive macrophages were higher in the Hubbs' beaked whales compared to those in the porpoises. Trematode species of the harbor and Dall's porpoises were Campula oblonga, while they were Oschmarinella macrorchis in the Hubbs' beaked whales. This study concludes that interspecies differences in the tissue reactions to hepatic trematode infections are present among odontocete species and that the immune reaction varies depending on the species. This information aids in furthering our understanding of the pathogenesis of hepatic trematodiasis in cetaceans.

Comparison of Three Histological Techniques for Fat Emboli Detection in Lung Cetacean's Tissue

Fat embolism is the mechanical blockage of blood vessels by circulating fat particles. It is frequently related to traumas involving soft tissues and fat-containing bones. Different techniques have been used for decades to demonstrate histologically fat emboli, being the extremely toxic post-fixation with osmium tetroxide one of the most used techniques in the last decades. In the present study, the osmium tetroxide technique was compared qualitatively and quantitatively, for the first time, with chromic acid and Oil Red O frozen techniques  for histological fat emboli detection in the lungs of eight sperm whales that died due to ship strikes. This was also the first time that chromic acid technique was tested in cetaceans. Results showed that the three techniques were valuable for the histological detection of fat embolism in cetaceans, even when tissues presented advanced autolysis and had been stored in formaldehyde for years. Although quantitative differences could not be established, the Oil Red O frozen technique showed the lowest quality for fat emboli staining. On the contrary, the chromic acid technique was proven to be a good alternative to osmium tetroxide due to its slightly lower toxicity, its equivalent or even superior capacity of fat emboli detection, and its significantly lower economic cost.

Facial Squamous Cell Carcinoma and Abdominal Peripheral Nerve Sheath Tumour with Rhabdomyoblastic Differentiation in a Rough-toothed Dolphin (Steno bredanensis)

We report the pathological features of a facial squamous cell carcinoma (SCC) and an abdominal peripheral nerve sheath tumour (PNST) with rhabdomyoblastic differentiation in an aged free-ranging rough-toothed dolphin (Steno bredanensis). The animal was found stranded dead in poor body condition. On external examination, there was a 25 × 7 × 3 cm extensively ulcerated area on the right maxillary region of the rostrum, involving the oral mucocutaneous junction with prominent nodular edges, severe soft tissue loss and extensive maxillary and premaxillary bone lysis. On abdominal dissection, a 5 × 4 × 3.5 cm pale tan to red, raised mass expanded the inner aspect of the right transverse abdominis muscle. Microscopically, the aggressive facial lesion was an acantholytic SCC with extensive osteolysis; there was no evidence of metastasis in the tissues examined. The abdominal mass had cytohistomorphological features compatible with a localized PNST, including whorling, Antoni A and Antoni B areas and Verocay bodies intermixed with rhabdomyoblastic components, as suggested by phosphotungstic acid haematoxylin stain. This neoplasm was locally infiltrative, yet no metastases were observed in the tissues examined. No immunohistochemical investigations could be performed due to lack of tissue availability. Total DNA from the formalin-fixed and paraffin wax-embedded SCC was extracted and tested by polymerase chain reaction for herpesvirus and papillomavirus genetic material. There was no amplification for either of these genera. Other pathological findings observed in this animal were related to the 'live-stranding stress response'. The severity and extent of the facial SCC likely related to anorexia and poor body condition and might have played a role in the stranding and death of this dolphin. These two tumour subtypes add to the relatively uncommon reports of neoplasia in cetaceans. Specifically, these appear to be the first neoplasia records for rough-toothed dolphins, including the first documentation of a PNST with features compatible with rhabdomyoblastic differentiation in a marine mammal.

Retrospective Study of Traumatic Intra-Interspecific Interactions in Stranded Cetaceans, Canary Islands

Aggressive encounters involving cetacean species are widely described in the literature. However, detailed pathological studies regarding lesions produced by these encounters are scarce. From January 2000 to December 2017, 540 cetaceans stranded and were necropsied in the Canary Islands, Spain. Of them, 24 cases of eight species presented social traumatic lesions produced by cetaceans of the same or different species. All the cases presented severe multifocal vascular changes, 50% (12/24) presented fractures affecting mainly the thoracic region, 41.7% (10/24) acute tooth-rake marks, 37.5% (9/24) undigested food in the stomach, 33.3% (8/24) tracheal edema, and 12.5% (3/24) pulmonary perforation. In 10 cases with tooth-rake marks, the distance between the teeth, allowed us to further identify the aggressor species: four cases were compatible with killer whales (Orcinus orca) affecting three species [pigmy sperm whale (Kogia breviceps), Cuvier's beaked whale (Ziphius cavirostris), and short-finned pilot whale (Globicephala macrorhynchus)] and four cases compatible with common bottlenose dolphins (Tursiops truncatus) affecting two species [short-beaked common dolphin (Delphinus delphis) and Atlantic spotted dolphin (Stenella frontalis)]. We also described two cases of intraspecific interaction in stripped dolphin (Stenella coeruleoalba). Microscopically, 70.8% (17/24) of the cases presented acute degenerative myonecrosis, 66.7% (14/21) presented vacuoles in the myocardiocytes, 36.8% (7/19) pigmentary tubulonephrosis, 31.6% (6/19) cytoplasmic eosinophilic globules within hepatocytes, 21.4% (3/14) hemorrhages in the adrenal gland, and 17.3% (4/23) bronchiolar sphincter contraction. The statistical analysis revealed that deep divers, in good body condition and nearby La Gomera and Tenerife were more prone to these fatal interactions. Additionally, in this period, three animals died due to an accident during predation: a false killer whale (Pseudorca crassidens) died because of a fatal attempt of predation on a stingray, and two Risso's dolphins (Grampus griseus) died as a consequence of struggling while predating on large squids.

Advances in research on the impacts of anti-submarine sonar on beaked whales

Mass stranding events (MSEs) of beaked whales (BWs) were extremely rare prior to the 1960s but increased markedly after the development of naval mid-frequency active sonar (MFAS). The temporal and spatial associations between atypical BW MSEs and naval exercises were first observed in the Canary Islands, Spain, in the mid-1980s. Further research on BWs stranded in association with naval exercises demonstrated pathological findings consistent with decompression sickness (DCS). A 2004 ban on MFASs around the Canary Islands successfully prevented additional BW MSEs in the region, but atypical MSEs have continued in other places of the world, especially in the Mediterranean Sea, with examined individuals showing DCS. A workshop held in Fuerteventura, Canary Islands, in September 2017 reviewed current knowledge on BW atypical MSEs associated with MFAS. Our review suggests that the effects of MFAS on BWs vary among individuals or populations, and predisposing factors may contribute to individual outcomes. Spatial management specific to BW habitat, such as the MFAS ban in the Canary Islands, has proven to be an effective mitigation tool and mitigation measures should be established in other areas taking into consideration known population-level information.

Increased Plasma Cardiac Troponin I in Live-Stranded Cetaceans: Correlation with Pathological Findings of Acute Cardiac Injury

Capture myopathy (CM), is a syndrome that occurs as the result of the stress during and after capture, handling, restraint, and transport of wild animals. Although CM has been described for many species of cetaceans, characterization of the acute cardiac injury - an important component of this syndrome - are still scarce. In this study, we firstly estimated a normal range for cardiac troponin I (cTnI) on cetaceans. Here, through biochemical analysis (especially of cTnI) and histopathological, histochemical, and immunohistochemical correlations with decreased troponin immunolabelling, we studied the cardiac injury in live-stranded cetaceans. Nine cetaceans which stranded alive on the Canary Islands (January 2016 - June 2019) were included in this study. Sampled individuals presented elevated values of plasma cTnI, which were correlated to histopathological lesions comprised of vascular changes and acute degenerative lesions. Immunohistochemically, injured cardiomyocytes showed a decreased intrafibrillar troponin immunoreaction. This is the first attempt to establish a normal baseline range for cTnI in cetaceans, and the first study comparing plasma biomarkers values with histopathological and immunohistochemical findings. This approach allowed us to demonstrate the degree of cardiac damage as a result of injury, consistent with ischemia-reperfusion lesions. The knowledge gained here could improve decision-making procedures during stressful situations, mainly in live-strandings, handling, and rehabilitation, thereby reducing the mortality of cetaceans.

Capture Myopathy and Stress Cardiomyopathy in a Live-Stranded Risso's Dolphin (Grampus griseus) in Rehabilitation

Simple Summary

Free-living cetaceans are threatened, daily, by a wide variety of stressful situations. An example is provided by live-stranding, in which a cetacean is alive on the beach or in shallow water, and unable to free itself and resume its normal activity. This is the first case of capture myopathy and stress cardiomyopathy in a live-stranded juvenile male Risso’s dolphin (Grampus griseus) with subsequent rehabilitation attempted. Valuable use of blood samples, and finally necropsy assessments, advances our understanding about the pathology common in live-stranded cetaceans.

Abstract

Capture myopathy (CM) is described in wild animals as a metabolic syndrome resulting from the extreme stress suffered during and after capture, handling, restraint, and transport. Although CM has been characterized in many species of cetaceans, descriptions of cardiac injury—an important component of this syndrome, and, according to previous authors, comparable to the existing human pathology so-called stress cardiomyopathy (SCMP)—are still rare. Therefore, the main aim of this report is to illustrate, for the first time, the biochemical analysis, and gross, histopathological, histochemical and immunohistochemical features of CM, and more specifically of the SCMP involved in this syndrome, caused by the live-stranding and consequent rehabilitation attempt, for a certain period of time, in a juvenile male Risso’s dolphin (Grampus griseus). The animal presented elevated values of creatine kinase, cardiac troponin I and blood urea nitrogen, with some variations during the rehabilitation period. Histologically, we detected vascular changes and acute degenerative lesions analogous to the ones observed in humans with SCMP. We consider this study to be an important contribution to the study of cetaceans since it could help in decision-making and treatment procedures during live-strandings and improve conservation efforts by reducing the mortality of these animals.

Skeletal and Cardiac Rhabdomyolysis in a Live-Stranded Neonatal Bryde's Whale With Fetal Distress

The main objective of wildlife forensic investigation is to recognize pathologic changes and cause of death. Even though it may not always be possible to determine the specific illness and/or etiology, the description and subsequent interpretation of the injuries provide an invaluable understanding of pathology in cetacean post-mortem investigations. Although pathological studies have been previously reported in various cetacean species, such descriptions of the infraorder Mysticeti remain rare. A live-stranded neonatal Bryde's whale (Balaenoptera edeni) which subsequently died soon after the stranding, was assessed by physical exam, blood examination, gross necropsy evaluation, histopathology, and immunohistochemistry. It presented with elevated serum levels of creatine kinase, cardiac troponin I, urea, and creatinine. Microscopically, we observed keratin spicules (squamous epithelial cells) and areas of atelectasis in the lungs. Acute degeneration in the myocytes and cardiomyocytes were comparable to the findings previously described in cases of capture myopathy in live-stranded cetaceans. Immunohistochemistry biomarkers such as myoglobin, fibrinogen, and troponin were analyzed. Skeletal and myocardial damage has been documented in several cetacean species. However, this is the first reported case of skeletal and cardiac rhabdomyolysis associated with live-stranding in a newborn Bryde's whale that suffered from fetal distress.

Pathologic findings and causes of death in southern right whales Eubalaena australis, Brazil

Southern right whales Eubalaena australis (SRWs) migrate to southern Brazil for breeding and calving from June through November. Overall, there is scarce knowledge on health status and pathologic conditions in SRWs. We report the pathologic and molecular investigation results of 8 SRWs that were necropsied between 2010 and 2017 within a breeding and calving ground in Santa Catarina state, Brazil. The animals were of various ages (7 newborns/calves, 1 adult) and sex (3 females, 5 males). Five whales stranded dead; 3 stranded alive and died shortly after (n = 2) or were euthanized (n = 1). The causes of stranding and/or death were neonatal respiratory distress syndrome with meconium aspiration (n = 3) with concomitant congenital hepatopathy in one of them; trauma of unknown origin (n = 3), infectious renal and lung disease with presumed sepsis (n = 1), and euthanasia (n = 1). Three animals were PCR-positive for cetacean morbillivirus; one of them also had morbilliviral antigen in kidney via immunohistochemical analysis. These results, integrating novel findings and a published report, contribute to the pathology knowledge of this species.

Renal and vaginal calculi in a free-ranging long-beaked common dolphin Delphinus capensis

Bilateral nephrolithiasis with a concurrent vaginal calculus was identified in a stranded free-ranging long-beaked common dolphin Delphinus capensis. Necropsy and radiologic examinations of the sexually mature D. capensis revealed multiple small irregularly round nephroliths and a 6.4 × 4.1 × 9.2 cm vaginal calculus weighing 182 g. Nephroliths numbered 68 and 71 in the left and right kidneys, respectively, and ranged from 1.7 to 6.9 mm in diameter. Nephroliths were composed of 100% ammonium urate, which has been found in captive dolphin populations. However, the vaginolith consisted of struvite and calcium carbonate suggesting an alternate etiology. The composition of the vaginolith suggests that bacterial vaginitis could have served as the predisposing condition. Renal lesions included chronic tubulointerstitial nephritis with tubular degeneration and loss, likely secondary to the nephroliths. The pathogenesis of ammonium urate nephrolithiasis in managed care is suspected to be linked to diet and age but in this case may be due to metabolic disruption. However, if environmental changes cause a shift in prey species, the risk of nephrolithiasis in free-ranging cetaceans could increase. Careful surveillance for nephroliths in free-ranging populations should be considered by researchers.

Stress cardiomyopathy in stranded cetaceans: a histological, histochemical and immunohistochemical study

BACKGROUND

Free-living cetaceans are exposed to a wide variety of stressful situations, including live stranding and interaction with human beings (capture myopathy), vessel strikes, and fishing activities (bycatch), which affect their wellbeing and potentially lead to stress cardiomyopathy (SCMP).

METHODS

Here, the authors aimed to characterise SCMP of stranded cetaceans as an injury resulting from extreme stress responses, based on pathological analyses (histological, histochemical and immunohistochemical). Specifically, the authors examined heart samples from 67 cetaceans found ashore (48 live strandings, seven dead from ship collision and 12 dead from bycatch) on the coast of Spain, more specifically in the Canary Islands from 2000 to 2016 and Andalusia from 2011 to 2014.

RESULTS

The microscopic findings were characterised by vascular changes, acute or subacute cardiac degenerative necrotic lesions, interstitial myoglobin globules, and infiltration of inflammatory cells. Immunohistochemically, cardiac troponin I, cardiac troponin C and myoglobin were depleted, along with fibrinogen being expressed in the degenerated/necrotic cardiomyocytes. A perivascular pattern was also identified and described in the damaged cardiomyocytes.

CONCLUSIONS

This study advances current knowledge about the pathologies of cetaceans and their implications on conserving this group of animals by reducing mortality and enhancing their treatment and subsequent rehabilitation to the marine environment.

Comparative Innate and Adaptive Immune Responses in Atlantic Bottlenose Dolphins (Tursiops truncatus) With Viral, Bacterial, and Fungal Infections

Free-ranging Atlantic bottlenose dolphins (n = 360) from two southeastern U.S. estuarine sites were given comprehensive health examinations between 2003 and 2015 as part of a multi-disciplinary research project focused on individual and population health. The study sites (and sample sizes) included the Indian River Lagoon (IRL), Florida, USA (n = 246) and Charleston harbor and associated rivers (CHS), South Carolina, USA (n = 114). Results of a suite of clinicoimmunopathologic tests revealed that both populations have a high prevalence of infectious and neoplastic disease and a variety of abnormalities of their innate and adaptive immune systems. Subclinical infections with cetacean morbillivirus and Chlamydiaceae were detected serologically. Clinical evidence of orogenital papillomatosis was supported by the detection of a new strain of dolphin papillomavirus and herpesvirus by molecular pathology. Dolphins with cutaneous lobomycosis/lacaziasis were subsequently shown to be infected with a novel, uncultivated strain of Paracoccidioides brasiliensis, now established as the etiologic agent of this enigmatic disease in dolphins. In this review, innate and adaptive immunologic responses are compared between healthy dolphins and those with clinical and/or immunopathologic evidence of infection with these specific viral, bacterial, and fungal pathogens. A wide range of immunologic host responses was associated with each pathogen, reflecting the dynamic and complex interplay between the innate, humoral, and cell-mediated immune systems in the dolphin. Collectively, these studies document the comparative innate and adaptive immune responses to various types of infectious diseases in free-ranging Atlantic bottlenose dolphins. Evaluation of the type, pattern, and degree of immunologic response to these pathogens provides novel insight on disease immunopathogenesis in this species and as a comparative model. Importantly, the data suggest that in some cases infection may be associated with subclinical immunopathologic perturbations that could impact overall individual and population health.