Enterolith with a bonefish spine nidus in a Brazilian cownose ray Rhinoptera brasiliensis (Müller & Henle) (Myliobatiformes: Rhinopteridae)

An adult female Brazilian cownose ray (Rhinoptera brasiliensis), housed in Ubatuba Aquarium died after loss of appetite period. During necropsy, an enterolith was discovered partially obstructing the intestinal lumen. Examination of the enterolith revealed a bonefish spine nidus. Enterolithiasis has been linked to multiple factors including diet, genetics, alkaline intestinal environments and, as in this particular case, the ingestion and retention of foreign bodies. The composition of this enterolith from a cownose ray was primarily monohydrocalcite. This short communication, apparently the first to report enterolithiasis in stingrays, emphasizes the need for post-mortem examinations of carcasses on macroscopic and microscopic levels.

DEVELOPING A THROMBOELASTOGRAPHY ASSAY IN ELASMOBRANCHS

Thromboelastography (TEG) is a hemostatic assay evaluating clot initiation time, kinetics, strength, and extent of fibrinolysis. Hemostatic assays in nonmammalian species have been less extensively studied because of lack of taxon-specific reagents and unique physiology. Hemostatic or hemorrhagic disease has been described postmortem in elasmobranchs, but antemortem detection of coagulopathies is limited in this taxon. The study aimed to establish an elasmobranch TEG protocol to improve hemostatic evaluation and facilitate advanced treatment options for animals under human care. Multiple clotting initiators were assessed for efficacy with frozen-thawed citrated plasma, fresh citrated plasma, and fresh whole citrated blood: RapidTEGTM, citrated kaolin, Reptilase®, and species brain-derived thromboplastin prepared by two different methods. Initial evaluation found plasma samples clot inconsistently, but TEG analyses using fresh whole blood consistently led to measurable TEG reactions using multiple clotting initiators. The most reliable elasmobranch TEG results were observed using citrated fresh whole blood and the RapidTEG clot initiation reagent.

Bacterial abscesses in whitespotted bamboo sharks (Chiloscyllium plagiosum) in managed care

Sixteen whitespotted bamboo sharks (Chiloscyllium plagiosum) with histologically similar bacterial abscesses were submitted to Northwest ZooPath from nine zoo and aquarium institutions over a 17-year period. These abscesses were characterized by inflammatory cell infiltrates and necrosis with intralesional small, Gram-positive, acid-fast negative, cocci bacteria. The clinical presentation, histologic findings, and culture results indicate that Enterococcus faecalis is a relatively common cause of these lesions in whitespotted bamboo sharks. This organism also provides a treatment challenge due to its inherent antibiotic-resistant properties and ability to form biofilms, confounding the host's immune response. Enterococcus faecalis represents an important cause for abscess formation and cellulitis in captive whitespotted bamboo sharks.

Review of neoplasia in fish at a large display aquarium, 2005-2021

Fish maintained in managed care may have longer lifespans as a result of advances in veterinary medicine and husbandry and reduced risk of predation. Neoplasia is of increasing interest in managed aquarium populations. However, few studies have systematically evaluated neoplasia in managed fish populations. Our objective in this retrospective study was to review and describe neoplasia diagnosed in fish at a large public display aquarium between 2005 and 2021. Any fish diagnosed with neoplasia on either antemortem or postmortem evaluation during the study period was included, and all medical records, biopsy, and autopsy reports were reviewed. Sixty-two fish met the inclusion criteria; 37 species were included in the study population, most of which were tropical freshwater fish (n = 34 fish). Thirty-two types of neoplasia were identified. Ten fish had benign neoplasms, and 53 fish had malignant neoplasms. The most common neoplasms were of epithelial and neuroectodermal origin. The most common site of tumor origin was the skin. Our data suggest that mesenchymal neoplasms may be more common in cold saltwater fish than in tropical freshwater and saltwater fish. Malignant neoplasms were most commonly diagnosed in the study population and should be a top differential when neoplasms are identified in fish managed under human care. Our study contributes to the overall knowledge of the health of aquarium fish and may aid clinicians in characterizing neoplasia that may be present in fish under human care.

Coping with current impacts: The case of Scyliorhinus canicula in the NW Mediterranean Sea and implications for human consumption

The small-spotted catshark (Scyliorhinus canicula) is a bottom-dwelling elasmobranch that represents the most discarded catch in terms of biomass in the Catalan coast (NW Mediterranean). Potential impacts affecting its population and food safety implications have been assessed in three localities along the Catalan coast. Distinct indicators were integrated, such as biological data, ingested anthropogenic items (plastic and cellulose-like items), parasitological indices, trace metal concentrations and histopathology using liver as target organ. Although high ingestion rates of fibres and levels of some heavy metals, they do not seem negatively affected by any major pathology nor by the current levels of pollutants. Small-scale differences among localities and depths were found and discussed. No zoonotic parasites were found. Encysted larvae of Grillotia adenoplusia and, above all, the levels of Hg found in the musculature, that are well over the European Commission limits, rise concerns regarding human consumption of S. canicula in this region.

PRIMARY HEPATIC NEOPLASIA IN THREE ADULT BAMBOO SHARKS (CHILOSCYLLIUM PLAGIOSUM AND CHILOSCYLLIUM PUNCTATUM) IN AN AQUARIUM POPULATION

Neoplasia in elasmobranchs is uncommonly documented. This report describes primary hepatic neoplasia in three adult female bamboo sharks under managed care: biliary adenocarcinoma in a whitespotted bamboo shark (Case 1; Chiloscyllium plagiosum), biliary adenocarcinoma in a brownbanded bamboo shark (Case 2; Chiloscyllium punctatum), and hepatocellular carcinoma in a whitespotted bamboo shark (Case 3). Case 1 presented with extensive cutaneous papillomas and was electively euthanized. At necropsy, a 4-cm-diameter, pale-tan, firm hepatic mass was identified and diagnosed histologically as a biliary adenocarcinoma. Case 2 presented with decreasing body condition despite normal food intake. Coelomic ultrasound and exploratory surgery revealed several large masses in both hepatic lobes, and the patient was euthanized. At necropsy, nine, 1-6-cm-diameter, black to tan, firm hepatic masses were identified and diagnosed histologically as biliary adenocarcinoma with branchial intravascular neoplastic emboli. Case 3 presented for routine health examination and was euthanized for diagnostic purposes after coelomic ultrasound revealed multiple hepatic masses. At necropsy, two 1-3-cm-diameter, brown- and-black mottled, firm hepatic masses were identified and diagnosed histologically as hepatocellular carcinoma. Immunohistochemistry was performed in two of these cases and was noncontributory, likely because of a lack of cross reactivity between antibodies (antipancytokeratin) and elasmobranch tissues.

Pharmacokinetics of the analgesic and anti-inflammatory drug meloxicam after administration of multiple doses to nursehound sharks (Scyliorhinus stellaris)

OBJECTIVE

To determine the pharmacokinetics of meloxicam in the nursehound shark (Scyliorhinus stellaris) during multiple dose administration.

STUDY DESIGN

Prospective experimental trial.

ANIMALS

A total of eight clinically healthy adult nursehounds (four males, four females).

METHODS

Meloxicam was administered intramuscularly at a dose of 1.5 mg kg-1 once daily for 7 days. Blood samples were collected from the caudal vein for pharmacokinetic analysis at 2.5 hours and 24 hours after drug administration. After a 4 week washout period, meloxicam was administered orally at the same dose at 12 hour intervals for three repeated doses. Blood samples were collected at 1, 2, 4, 6, 8, 12, 24, 36 and 48 hours after the first administration. Sharks were visually monitored during each study and 4 weeks afterwards for side effects or signs of toxicity. Time required to achieve steady state was assessed by visual inspection and statistical comparison of peak and trough concentrations using a Friedman test; comparison between sexes was performed using a Mann-Whitney U test and p-value was set at 0.05.

RESULTS

No animal died or showed clinical signs of toxicity during the study. Meloxicam administered orally did not produce detectable concentrations in plasma. After intramuscular administration, steady state was achieved after five doses, and mean trough and peak plasma concentrations at steady state were 1.76 ± 0.21 μg mL-1 and 3.02 ± 0.23 μg mL-1, respectively. Mean peak concentration accumulation ratio was 2.50 ± 0.22.

CONCLUSIONS AND CLINICAL RELEVANCE

This study shows that intramuscular posology produces plasma concentrations considered therapeutic for other species. However, meloxicam was not detected in plasma after oral administration. These results suggest that meloxicam administered intramuscularly may be a useful non-steroid anti-inflammatory drug in nursehound sharks. Further pharmacodynamic studies are needed to fully evaluate its clinical use in this species.

CLINICAL AND HISTOPATHOLOGIC OCULAR FINDINGS IN AQUARIUM-HOUSED COWNOSE RAYS (RHINOPTERA BONASUS)

Cownose rays (Rhinoptera bonasus) are susceptible to ocular disease with their prominent globes, but despite being popular animals housed in aquaria, there is little published information about their normal ocular anatomy and common pathologic ocular findings. A total of 63 live cownose rays (CNR) from three unrelated, separately housed groups had ocular examinations, and 5 adult rays were selected for ocular ultrasound. All examinations were performed out of the water, and most without anesthesia. Clinical findings were described, categorized, and scored by severity. Sixty-two of 63 rays (123 eyes) had clinical abnormalities, including 110 eyes with corneal pathology (mild = 76, moderate/severe = 34) and 74 eyes with intraocular pathology (mild = 44, moderate/severe = 30). Grey-to-white corneal opacities were the most common pathology (n = 58 rays/100 eyes) followed by cataracts (n = 41 rays/58 eyes), then persistent (or dysplastic) pupillary membranes (n = 14 rays/15 eyes). Most pathologic findings appeared inactive, but one aquarium had several CNR with active ocular pathology. There was a significant association between the diagnosis of moderate/severe corneal and intraocular pathology with age (P = 0.008 and P = 0.014, respectively) and weight (P = 0.001 and P = 0.039, respectively), as well as moderate/severe corneal pathology and group sampled (P = 0.03). There were no other significant variables identified. Additionally, histopathology of 14 eyes (11 rays) from two different facilities were examined, with keratitis (n = 8) and uveitis (n = 2) as the most common lesions. This study shows a high prevalence of pathologic ocular findings in cownose ray eyes with heavier adults more likely to be affected than lighter juveniles. Comprehensive ocular evaluation is important in this species and serial ocular exams and future studies should be pursued to monitor ocular disease progression and better understand possible etiologies.

Fungal Diseases in Elasmobranchs and Their Possible Treatment with a Special Mention to Azole Antifungal Agents

INTRODUCTION

Elasmobranchs currently constitute an important part of the animal collection of many aquariums worldwide. Their maintenance under human care has allowed us to describe and identify new pathogens and diseases affecting them, as well as to determine different treatments for these diseases. Great advances in elasmobranch husbandry have been developed.

METHODS

A search was performed on scientific databases as PubMed and other specialized sources (IAAAM archive).

RESULTS

Little information on pharmacotherapeutics is available in this taxonomic group, and treatments lack a scientific base and instead are frequently dependent on empirical knowledge. Pharmacokinetic studies are the first step to determining therapeutic protocols that are safe and effective. The available bibliography shows that a majority of the mycoses recorded in cartilaginous fish are severe, aggravated by the fact that the antifungal treatments administered, following the guidelines used for teleost species, are ineffective in elasmobranchs. Azoles appear to be a promising group of antifungals for use in treating systemic mycoses in sharks and rays.

CONCLUSIONS

Based on the findings of this review, it is essential to investigate the pharmacokinetics of the different antifungals in these species in order to provide therapeutic options for fungal infections in cartilaginous fish.

Caudal peduncle mineralized lesion resembling calcinosis circumscripta in a wels catfish Silurus glanis

This report presents an intriguing case of a mineralized lesion resembling calcinosis circumscripta observed in the caudal peduncle of a wels catfish, housed in a public aquarium in northern Italy. The investigation encompasses a comprehensive analysis of various aspects, including clinical presentation, diagnostic imaging, as well as gross and microscopic pathology, and immunohistochemistry. Histopathology, in particular, highlighted a severe focally extensive granulomatous reaction, confirmed by dense histiocytic inflammatory infiltrates and the massive presence of multinucleated foreign body type giant cells localized around lakes and aggregates of mineralized material. Moreover, the usefulness and limitations of immunohistochemistry and special stains in characterizing fish tissues and cell types are highlighted. Although reported in elasmobranchs and sturgeons, to our knowledge, this is the first description of calcinosis circumscripta in teleost fish and it offers valuable insights into the understanding of similar pathologies in aquatic organisms.

DEXMEDETOMIDINE AND MIDAZOLAM INTRAMUSCULAR SEDATION IN BROWNBANDED BAMBOO SHARKS (CHILOSCYLLIUM PUNCTATUM)

Bamboo sharks are some of the most common elasmobranch species in zoos and aquaria and are frequently sedated for medical exams, treatments, and research. This study investigated the use of an IM sedation protocol of a single dose of dexmedetomidine (0.05 mg/kg) and midazolam (2.0 mg/kg) in brownbanded bamboo sharks (Chiloscyllium punctatum). Sharks were serially monitored every 5 min for heart rate, branchial beats, righting reflex, coelomic response, cloacal response, pelvic fin reflex, response to noxious stimulus, voluntary movement, and ability to swim. This sedation dose was effective at rapidly and significantly decreasing responses to tactile and noxious stimuli with minimal respiratory depression and was quickly reversible with atipamezole (0.5 mg/kg) and flumazenil (0.05 mg/kg). Sedated sharks developed a mild metabolic acidosis evidenced by a significant increase in lactic acid (mean < 0.37 mmol/L presedation, 4.2 mmol/L after reversal) and decrease in blood pH (mean 7.464 presedation, 7.277 after reversal); however, clinical intervention was not required. This protocol should be further investigated in different elasmobranch species but is promising for providing sedation for noninvasive procedures in brownbanded bamboo sharks.

Identification and characterization of a polyomavirus in the thornback skate (Raja clavata)

Members of the family Polyomaviridae have a circular double-stranded DNA genome that have been identified in various hosts ranging from mammals to arachnids. Here we report the identification and analysis of a complete genome sequence of a novel polyomavirus, Raja clavata polyomavirus (RcPyV1), from a cartilaginous fish, the thornback skate (Raja clavata). The genome sequence was determined using a metagenomics approach with an aim to provide baseline viral data in cartilaginous fish in different ecosystems. The RcPyV1 genome (4,195 nucleotides) had typical organization of polyomavirus, including early antigens (small T; Large T) encoded on one strand and late viral proteins (VP1; VP2) on the complementary strand. Maximum-likelihood phylogenetic analysis of the large T-antigen revealed that RcPyV1 clusters with a polyomavirus obtained from another cartilaginous fish, the guitarfish polyomavirus 1 (GfPyV1). These two share ~ 56% pairwise identity in LT and VP1 protein sequences. These analyses support the hypothesis that cartilaginous fishes have a specific lineage of polyomaviruses.

A Novel One Health Approach concerning Yeast Present in the Oral Microbiome of the Endangered Rio Skate (Rioraja agassizii) from Southeastern Brazil

The current climate change scenario caused by anthropogenic activities has resulted in novel environmental pressures, increasing the occurrence and severity of fungal infections in the marine environment. Research on fungi in several taxonomic groups is widespread although not the case for elasmobranchs (sharks and rays). In this context, the aim of the present study was to screen the oral fungal microbiota present in artisanally captured Rioraja agassizii, a batoid that, although endangered, is highly fished and consumed worldwide. Oropharyngeal samples were obtained by swabbing and the samples were investigated using morphological and phenotypic methods by streaking on Sabouraud Dextrose Agar (SDA) and subculturing onto CHROMagar Candida (BD Difco) and CHROMagar Candida Plus (CHROMagarTM), as well as molecular techniques by amplification of the ITS1-5.8S-ITS2 ribosomal DNA region and a MALDI-TOF MS assessment. The findings indicated the presence of Candida parapsilosis (seven isolates), Candida duobushaemulonii (one isolate) and Rhodotorula mucilaginosa (three isolates), several of these reported for the first time in Rioraja agassizii. In addition, a 100% agreement between the MALDI-TOF results and partial ITS region sequencing was noted, demonstrating that the MALDI-TOF MS is a rapid and effective alternative for yeast identification in Rioraja agassizii isolates and potentially in other elasmobranch species. These findings highlight the need for further research to determine the potential impact on elasmobranch health, ecology, and commercial fisheries. Furthermore, this research is paramount in a One Health framework and may be employed to predict elasmobranch responses to an evolving ocean, keep healthy populations in check, monitor species, and assess the public health consequences of consuming these species.

Case series: Lymphoid neoplasia in three elasmobranch species

Elasmobranchs (sharks and rays) are charismatic cartilaginous fish, popular in public aquaria. Almost 200 shark and ray species are listed as threatened by the International Union for Conservation of Nature (IUCN), demonstrating the importance of captive breeding and research programmes. Limited studies investigate diseases of elasmobranchs in captive and free-living environments, and among available literature neoplasia is rarely reported, with even fewer cases of lymphoid neoplasia documented. This article outlines the first reports of lymphoid neoplasia in three elasmobranch species in which haematopoietic neoplasms have not been reported to date. It summarizes signalment, history and histopathologic findings in an undulate ray, Raja undulata (Lacepede), a common smooth-hound, Mustelus mustelus (Linnaeus) and a bat ray, Myliobatis californica (Gill). Lesions were confirmed in a wide range of tissues and evidence of lymphoid leukaemia was seen in two cases. This small-scale review demonstrates that lymphoid neoplasia should be considered as a differential diagnosis in elasmobranchs presenting with lethargy and anorexia and highlights the challenges of immunohistochemical work up.

Contrast-enhanced computed tomography and cross-sectional anatomy of the trunk in the brownbanded bamboo shark (Chiloscyllium punctatum)

Computed tomography (CT) is used in veterinary medicine for the diagnosis of bones and soft tissue diseases in various species. In addition, CT has recently been used to diagnose aquatic animals, including Selachimorpha, which are difficult to diagnose out of water. However, because Selachimorpha do not have adipose tissue in the coelomic cavity, the coelomic organs cannot be fully identified using non-contrast CT (NCCT). The aim of this study is to present the anatomical features of the cadaver, NCCT, and contrast-enhanced CT (CECT) as well as the change in CT values of the coelomic organs and musculature of the brownbanded bamboo shark. NCCT scans were performed under anaesthesia in one male and one female shark. CECT was performed 30 min after iopamidol was administered intravenously. The sharks were euthanized, frozen at -20°C, and sliced in the same position in which they were scanned. Using electric band saw, 10-mm transversal sections were obtained. The anatomical structures of both males and females were identified by transversal sections, and CT images homologous to transversal sections were then selected. Sagittal and coronal CECT images were also obtained to facilitate understanding of the location and size of coelomic organs. Although bone structure and air in organs could be sufficiently discriminated on NCCT image, the coelomic organs were almost indistinguishable. On the other hand, CECT images obtained sufficient contrast to identify most coelomic organs in addition to bone and air. The results provide an atlas of a cross-sectional anatomy and CECT images, which is useful information for the medical diagnosis of coelomic organs in live Selachimorpha.

Ocular pathology in aquarium fish with a focus on the Syngnathidae and Apogonidae families

This study catalogued ocular pathology in fish histopathology submissions to a specialist diagnostic service and investigated associations with species and systemic disease, with a focus on species of conservation interest. Cross-tabulations and Fisher's exact tests were used to identify associations among the variables and results are reported as prevalence ratios (PRs) with 95% confidence intervals (CI). Of 12,488 reports reviewed, ocular histology examination was available for 4,572 submissions, in which histopathological ocular lesions were identified in 18% (813/4572). Most diagnoses (701/813; 87%) were in marine fish. Inflammatory conditions were most common (608/813; 75%), with identification of a bacterial aetiology in 42% (255/608) and a parasitic aetiology in 30% (183/608). Most bacterial infections were due to mycobacteriosis (153/255; 60%) and most parasitic infections were due to scuticociliatosis (114/184; 62%). The Syngnathidae, Centriscidae and Cichlidae families were each more likely than all other families combined to be diagnosed with ocular manifestations of mycobacteriosis (PRs = 2.6, 4.4 and 2.9, respectively, P <0.0001 for each). The Syngnathidae were also more likely to be diagnosed with ocular scuticociliatosis (PR = 1.9, P <0.0001). Fifty-four percent (39/72) of ocular mycobacteriosis and 38% (9/24) of gas bubble disease cases affected threatened or near threatened Syngnathidae species. The Apogonidae were more likely than any other family to have ocular iridovirus (PR = 10.3, 95% CI = 5.5-19.4, P <0.0001) and neoplasia (PR = 8.2, 95% CI = 4.2-16.3, P <0.0001). The endangered Banggai cardinalfish (Pterapogon kauderni) accounted for 13/15 ocular iridovirus and 16/18 mycobacteriosis cases in this family. All cases of neoplasia in the Apogonidae occurred in pajama cardinalfish (Sphaeramia nematoptera). These results should inform clinical diagnosis of ocular disease in aquarium fish and influence training for aquarists, highlighting ocular pathology as a potential early warning of systemic disease. The findings also have direct/indirect consequences for the welfare and conservation of some of these popular flagship fish species.

Phage Diving: An Exploration of the Carcharhinid Shark Epidermal Virome

The epidermal microbiome is a critical element of marine organismal immunity, but the epidermal virome of marine organisms remains largely unexplored. The epidermis of sharks represents a unique viromic ecosystem. Sharks secrete a thin layer of mucus which harbors a diverse microbiome, while their hydrodynamic dermal denticles simultaneously repel environmental microbes. Here, we sampled the virome from the epidermis of three shark species in the family Carcharhinidae: the genetically and morphologically similar Carcharhinus obscurus (n = 6) and Carcharhinus galapagensis (n = 10) and the outgroup Galeocerdo cuvier (n = 15). Virome taxonomy was characterized using shotgun metagenomics and compared with a suite of multivariate analyses. All three sharks retain species-specific but highly similar epidermal viromes dominated by uncharacterized bacteriophages which vary slightly in proportional abundance within and among shark species. Intraspecific variation was lower among C. galapagensis than among C. obscurus and G. cuvier. Using both the annotated and unannotated reads, we were able to determine that the Carcharhinus galapagensis viromes were more similar to that of G. cuvier than they were to that of C. obscurus, suggesting that behavioral niche may be a more prominent driver of virome than host phylogeny.

Hematology and Plasma Chemistry Reference Values in Nursehound Shark (Scyliorhinus Stellaris) Maintained Under Human Care

Studies determining baseline hematological reference intervals (RI) in elasmobranchs are very limited. In this study, blood samples were collected from 94 clinically healthy Nursehound Shark (Scyliorhinus stellaris) maintained under human care. Median (RI) in major leukocyte types were similar to other Carcharhinid sharks as lymphocytes were the predominant leukocyte with 38.0 (28.2–53.5)%, followed by coarse eosinophilic granulocytes with 20.0 (12.2–31.7)%, fine eosinophilic granulocytes with 6.0 (1.2–12.8) %, monocytes with 2.0 (0.0–6.0)%, and neutrophils with 2.0 (0.0–6.0)%. Nursehound Shark produced granulated thrombocytes, which were classified as granulocytes and represented 28.5 (12.4–39.7)% of all leukocytes. Median (RI) manual red blood cell and white blood cell counts were 177.50 (132.50–210.00) x 109 cells/l and 8.26 (5.24–14.23) x 109 cells/l, respectively. Median (RI) plasma chemistry values showed alkaline phosphatase 7.7 (4.2–13.0) U/l, aspartate aminotransferase 7.6 (3.3–17.1) U/l, blood urea nitrogen 281.6 (261.2–305.0) mmol/l, calcium 3.97 (3.59–4.47) mmol/l, total cholesterol 2.04 (1.02–3.91) mmol/l, chloride 233.0 (215.2–259.0) mmol/l, iron 3.79 (1.74–6.93) μmol/l, glucose 0.87 (0.47–1.44 mmol/l), potassium 3.8 (2.9–4.6) mmol/l, sodium 243.0 (227.7–271.0) mmol/l, phosphorus 1.58 (1.13–2.10) mmol/l, total protein 24.0 (20.0–35.0) g/l, and triglycerides 0.97 (0.49–3.35) mmol/l. Creatine kinase, gamma glutamyl transferase, and lactate dehydrogenase levels were below the instrument reading range.

PHARMACOKINETICS OF MELOXICAM AFTER A SINGLE 1.5 MG/KG INTRAMUSCULAR ADMINISTRATION TO NURSEHOUND SHARKS (SCYLIORHINUS STELLARIS) AND ITS EFFECTS ON HEMATOLOGY AND PLASMA BIOCHEMISTRY

A single-dose meloxicam pharmacokinetic (PK) study was performed with eight clinically healthy nursehound sharks (Scyliorhinus stellaris) maintained under human care. Meloxicam was administered IM at a dosage of 1.5 mg/kg to six animals; two animals were administered elasmobranch physiological saline solution (EPSS) IM as a negative control group. Blood samples were obtained prior to and at 12 predetermined times during the first 36 h after administration. Effects on hematology and plasma biochemistry were compared prior to and 24 h after administration. No animal died or showed clinical signs during the study. A significant increase in creatinine kinase and aspartate aminotransferase was found in both EPSS and meloxicam groups and could be considered a direct consequence of sampling and handling required for the PK study. Observed mean time to maximum plasma concentration ± SEM was 2.58 ± 0.47 h and observed mean maximum plasma concentration ± SEM was 806 ± 66 ng/ml; mean terminal half-life ± SEM was 15.97 ± 1.20 h; mean residency time ± SEM was 23.40 ± 2.25 h. Area under the plasma concentration-versus-time curve extrapolated to infinity ± SEM was 15.52 ± 1.70 h·µg/ml. This study suggests that meloxicam 1.5 mg/kg IM in nursehound sharks is likely to result in clinically relevant plasma levels for periods of 24 h without producing significant alterations in blood analytics, although further PK studies with meloxicam IV in sharks are needed. Future PK and pharmacodynamic studies with different drugs and doses are needed in elasmobranchs to establish safe and effective treatment protocols.

FELASA-AALAS Recommendations for Monitoring and Reporting of Laboratory Fish Diseases and Health Status, with an Emphasis on Zebrafish (Danio Rerio)

The exchange of fish for research may expose an aquatic laboratory to pathogen contamination as incoming fish can introduce bacteria, fungi, parasites, and viruses capable of affecting both experimental results and fish and personnel health and welfare. To develop risk mitigation strategies, FELASA and AALAS established a joint working group to recommend good practices for health monitoring of laboratory fish. The recommendations address all fish species used for research, with a particular focus on zebrafish (Danio rerio). First, the background of the working group and key definitions are provided. Next, fish diseases of high impact are described. Third, recommendations are made for health monitoring of laboratory fishes. The recommendations emphasize the importance of daily observation of the fish and strategies to determine fish colony health status. Finally, report templates are proposed for historical screening data and aquatic facility description to facilitate biohazard risk assessment when exchanging fish.

Pharmacokinetics of the Anti-Inflammatory Drug Meloxicam after Single 1.5 mg/kg Intramuscular Administration to Undulate Skates (Raja undulata)

The therapy database currently used in elasmobranchs is still mostly based on empirical data, and there are few efficacy and safety studies supporting clinical practice. In this study, meloxicam pharmacokinetics (PK) were evaluated after a single 1.5 mg/kg IM administration to a group of seven clinically healthy adult undulate skates (Raja undulata Lacepède, 1802). Blood samples were collected before administration and at 15, 30, 60 and 90 min and 2, 4, 8, 12, 24 and 48 h after the IM injection. The meloxicam concentrations in plasma were determined using high-performance liquid chromatography, and PK parameters were calculated using a non-compartmental model approach. The mean ± SEM values of the main PK values were 1.84 ± 0.31 μg/mL for peak plasma concentration, 1.5 ± 0.24 h for time to maximum plasma concentration, 11.43 ± 2.04 h·µg/mL for area under the plasma concentration vs. time curve, 3.55 ± 0.65 h for elimination half-life, and 5.37 ± 0.94 h for mean residency time. No adverse reactions were detected. The relatively high plasma concentration and short time to maximum plasma concentration suggest that meloxicam could turn into an efficient analgesic and anti-inflammatory candidate drug to be used in skates. Further efficacy, pharmacodynamic, and multiple-dose studies with meloxicam are needed in elasmobranchs.

Pharmacokinetic Studies in Elasmobranchs: Meloxicam Administered at 0.5 mg/kg Using Intravenous, Intramuscular, and Oral Routes to Nusehound Sharks (Scyliorhinus stellaris)

Infectious and inflammatory diseases are the most frequently diagnosed pathologies in elasmobranchs maintained under human care. Non-steroidal anti-inflammatory drugs (NSAIDs) are frequently used in veterinary medicine for their anti-inflammatory, analgesic, and antipyretic properties. Meloxicam is a commonly prescribed NSAID in elasmobranchs, but there are still no published pharmacokinetic (PK) studies supporting its use in this group of animals. In this study, meloxicam was administered at a single dose of 0.5 mg/kg to eight healthy adult nursehound sharks (Scyliorhinus stellaris) intravenously (IV), intramuscularly (IM), and orally (PO), with a minimum 4-week washout period between administrations. Blood samples were obtained both beforehand and at predetermined times after each administration. Plasma concentrations were measured using a validated high performance liquid chromatography method, and PK data was obtained using a non-compartmental analysis. Meloxicam administered orally did not produce detectable concentrations in blood plasma, while mean peak plasma concentration was 0.38 ± 0.08 μg/ml after IM administration. The mean terminal half-life was 10.71 ± 2.77 h and 11.27 ± 3.96 h for IV and IM injections, respectively. The area under the curve extrapolated to infinity was 11.37 ± 2.29 h·μg/ml after IV injections and 5.98 ± 0.90 h·μg/ml after IM injections. Meloxicam administered IM had a mean absolute bioavailability of 56.22 ± 13.29%. These numbers support meloxicam as a promising drug to be used IM in nursehounds, questions the efficacy of its single PO use in elasmobranchs, elucidate the need for higher dosage regimes, and evidence the need for further PK studies in sharks and rays.

The Establishment of an Optimal Protocol for Contrast-Enhanced Micro-Computed Tomography in the Cloudy Catshark Scyliorhinus torazame

The purpose of this study was to determine the optimal imaging protocol for contrast-enhanced computed tomography (CECT) using micro-CT (μ-CT) for the posterior cardinal vein (PCV), dorsal aorta (DA), hepatic portal vein (HPV), kidney, liver, cephalic arteries (CAs), and gills of Cloudy Catsharks Scyliorhinus torazame. Additionally, we examined the availability of CECT screening for the coelomic organs. Different doses of iopamidol (100, 300, 500, and 700 mg iodine [mgI]/kg) were administered intravenously for 20 s in six sharks. The CT scans from the pectoral girdle to the pelvic girdle were performed at 0-600 s after administration. Contrast-enhanced CT imaging of the CAs, gills, and coelomic organs was examined. Assessment of the signal enhancement value revealed that the PCV was easily visualized with all contrast doses at 25 s. The CAs, gills, and DA were visible at a slightly higher dose (CAs and gills: 200 mgI/kg at 40 s; DA: 300 mgI/kg at 50 s). The HPV was obvious at a dose of at least 500 mgI/kg after a 150-s delay. The parenchyma of the kidney had a contrast effect at 300 mgI/kg, 150 s after the contrast effect of the renal portal system disappeared. The liver, which stores a lot of lipids, had poor overall contrast enhancement that was optimized at the highest dose of 700 mgI/kg. Contrast-enhanced CT screening at 700 mgI/kg and 150 s is likely to obtain the optimal imaging of the reproductive organs, such as the ovary, oviducal gland, uterus, and testis. The present findings can be applied not only to clinical practice but also to academic research and education on elasmobranchs in aquariums.

A novel herpes-like virus inducing branchial lesions in a tiger shark (Galeocerdo cuvier)

A juvenile, male tiger shark (Galeocerdo cuvier) developed illness after capture in Florida waters and was euthanized. Gross lesions included mild skin abrasions, hepatic atrophy, and coelomic fluid. Histologically, gills contained multifocal lamellar epithelial cell necrosis and thromboses. Scattered gill and esophageal epithelial cells had large, basophilic, intracytoplasmic, and intranuclear inclusions. Ultrastructurally, lamellar epithelial cells contained arrays of intracytoplasmic viral particles and scattered intranuclear nucleocapsids. Capsulated virions were 148 ± 11 nm with an 84 ± 8 nm icosahedral nucleocapsid and an electron-dense core. Next-generation sequencing, quantitative polymerase chain reaction, and in situ hybridization performed on formalin-fixed tissue confirmed a herpes-like viral infection. The viral polymerase shared 24% to 31% protein homology with other alloherpesviruses of fish, indicating a divergent virus. This report documents the pathologic findings associated with a molecularly confirmed novel herpes-like virus in an elasmobranch.

Retrospective study of phaeohyphomycosis in aquarium-housed fish, with first descriptions of Exophiala lecanii-corni and Neodevriesia cladophorae in fish

A broadening fish host range is affected by novel and known pigmented fungal pathogens. A review of 2,250 piscine submissions received by the Aquatic Pathology Service, University of Georgia, revealed 47 phaeohyphomycosis cases (2.1%), representing 34 bony and cartilaginous fish species. The majority involved bony fish (45/47, 95.7%) and were predominantly marine (41/47, 87.2%), with only a few freshwater species (4/47, 8.5%). Cartilaginous fish cases included two zebra sharks (Stegostoma fasciatum) (2/47, 4.3%). Northern seahorses (Hippocampus erectus) had the highest incidence overall (7/47, 14.9%). Culture and sequencing of the internal-transcribed spacer region of the rDNA (ITS), large ribosomal subunit gene D1/D2 domains (LSU) and the DNA polymerase II gene (RPB2) were performed for fungal identification when fresh tissue was obtainable. Exophiala, Ochroconis and Neodevriesia spp. were identified, with Exophiala as the most common fungal genus (8/11, 72.7%). Exophiala lecanii-corni and Neodevriesia cladophorae were described for the first time from fish. Microscopically, lesions were characterized by necrosis, granulomatous inflammation and angioinvasion most frequently affecting the skin/fin, skeletal muscle and kidneys. In this study of diverse aquarium-housed fish species, phaeohyphomycosis cases occurred sporadically and in rare outbreaks with variable pathologic presentations, tissue distributions and severities.

Elasmobranch microbiomes: emerging patterns and implications for host health and ecology

Elasmobranchs (sharks, skates and rays) are of broad ecological, economic, and societal value. These globally important fishes are experiencing sharp population declines as a result of human activity in the oceans. Research to understand elasmobranch ecology and conservation is critical and has now begun to explore the role of body-associated microbiomes in shaping elasmobranch health. Here, we review the burgeoning efforts to understand elasmobranch microbiomes, highlighting microbiome variation among gastrointestinal, oral, skin, and blood-associated niches. We identify major bacterial lineages in the microbiome, challenges to the field, key unanswered questions, and avenues for future work. We argue for prioritizing research to determine how microbiomes interact mechanistically with the unique physiology of elasmobranchs, potentially identifying roles in host immunity, disease, nutrition, and waste processing. Understanding elasmobranch–microbiome interactions is critical for predicting how sharks and rays respond to a changing ocean and for managing healthy populations in managed care.

Mercury in neonatal and juvenile blacktip sharks (Carcharhinus limbatus). Part II: Effects assessment

As apex predators, blacktip sharks (Carcharhinus limbatus) are highly susceptible to biomagnified mercury (Hg) particularly in the Gulf of Mexico (GOM), which is known to contain fishes and invertebrates with elevated Hg levels. Blacktip sharks occur in the GOM year-round and are heavily fished both commercially and recreationally, but little is known about how Hg affects the species. In this study, blood, muscle, liver, and kidney samples were collected from neonatal (n = 57) and juvenile (n = 13) blacktip sharks in Charlotte Harbor, Florida. Hg concentrations in neonates and juveniles were found to be elevated in muscle (mean ± SE = 0.59 ± 0.23 mg kg^-1), liver (0.39 ± 0.29 mg kg^-1), kidney (0.56 ± 0.25 mg kg^-1), and blood (0.059 ± 0.041 mg kg^-1) compared to other local shark species and conspecifics from other areas. Blood plasma chemistry, hematology, and liver histology were evaluated to assess the relationship between Hg and tissue damage. Plasma chemistry parameters alanine aminotransferase (ALT) and phosphorus (PHOS) were not correlated with tissue Hg or liver condition index. Hematological effects were also not correlated with tissue Hg. However, melanomacrophage presence and lipid deposition, evaluated as part of histopathological analysis, were found to exhibit a statistically significant association with concentrations of Hg in tissue and ALT levels. These results suggest that Hg exposure potentially had a negative effect on the livers of the blacktip sharks evaluated in the present study.

Wound-healing capabilities of whale sharks (Rhincodon typus) and implications for conservation management

Wound healing is important for marine taxa such as elasmobranchs, which can incur a range of natural and anthropogenic wounds throughout their life history. There is evidence that this group shows a high capacity for external wound healing. However, anthropogenic wounds may become more frequent due to increasing commercial and recreational marine activities. Whale sharks are particularly at risk of attaining injuries given their use of surface waters and wildlife tourism interest. There is limited understanding as to how whale sharks recover from injuries, and often insights are confined to singular opportunistic observations. The present study makes use of a unique and valuable photographic data source from two whale shark aggregation sites in the Indian Ocean. Successional injury-healing progression cases were reviewed to investigate the characteristics of injuries and quantify a coarse healing timeframe. Wounds were measured over time using an image standardization method. This work shows that by Day 25 major injury surface area decreased by an average of 56% and the most rapid healing case showed a surface area reduction of 50% in 4 days. All wounds reached a point of 90% surface area closure by Day 35. There were differences in healing rate based on wound type, with lacerations and abrasions taking 50 and 22 days to reach 90% healing, respectively. This study provides baseline information for wound healing in whale sharks and the methods proposed could act as a foundation for future research. Use of a detailed classification system, as presented here, may also assist in ocean scale injury comparisons between research groups and aid reliable descriptive data. Such findings can contribute to discussions regarding appropriate management in aggregation areas with an aim to reduce the likelihood of injuries, such as those resulting from vessel collisions, in these regions or during movements between coastal waters.

Geriatric Freshwater and Marine Fish

As pain management finally becomes accepted for this last of the vertebrate taxa, fish medicine is finally reaching the sophistication of other vertebrates. The diseases of aging fish in captivity therefore need to be addressed. The degenerative organ/tissue changes and neoplasias of fish deserve the same diagnosis and treatments of their terrestrial counterparts including pain relief, anti-inflammatory medications, chemotherapy, surgery, joint supplements, regenerative cell therapy, and photobiomodulation. Besides the challenges of an aquatic environment, recognizing normal changes in older fish will be addressed in this article. Clinicians can appreciate the diversity of fishes and their unique anatomies, physiologies, and behaviors which translate to creative medicine.

Histologic Observations of Dermal Wound Healing in a Free-Ranging Blacktip Shark from the Southeastern U.S. Atlantic Coast: A Case Report

Despite indications that sharks have an exceptional capacity to heal from traumatic injuries, no detailed microscopic observations of integumental wounds have been reported for sharks. This study details the histopathological features of such wounds in a free-ranging shark. An adult male Blacktip Shark Carcharhinus limbatus was collected in 2017 during fisheries-independent sampling efforts in the coastal southeastern U.S. Atlantic. The shark had numerous lesions on his head, torso, and left pectoral fin that were compatible with shark bites. Representative samples from two wounds on the head were examined by light microscopy. The epidermal changes included hyperplasia and hypertrophy; intracellular edema; and the absence of goblet cells, denticles, and chromatophores. In the dermis, fibrinocellular exudation, granulation tissue, and marked skeletal muscle necrosis and regeneration were observed. The above features were comparable to wound healing in bony fish, albeit minor differences were found. Although this case documents exceptionally good regeneration of skeletal muscle in the shark, we found no evidence of unique morphological healing patterns. Further studies on wound healing are needed because recent molecular and genetic findings do suggest evolutionary adaptations enhancing healing in sharks.

Physiological Impairment as a Result of Bile Accumulation in an Apex Predator, the Tiger Shark (Galeocerdo cuvier Péron & Lesueur, 1822)

Simple Summary

Sharks rely on a diet with high lipid content, depending on gallbladder proper functioning for lipid emulsification, absorption, and subsequent hepatic storage. The present study reports a physiological impairment due to bile accumulation in juvenile tiger sharks and the possible causes of such condition.

Abstract

Physiological adaptations have evolved to help sharks face rapid periods of feast. Tiger sharks are generalist apex predators that rely on a high-lipid/protein diet. To achieve a satisfactory nutritional condition, proper lipid absorption and hepatic storage are needed. Bile secretion in sharks is low and sporadic but increases during short periods of fasting. The present study describes a physiological impairment caused by bile accumulation in juvenile tiger sharks, possibly due to prolonged fasting. These evidences suggest that, even though sharks have adaptations that prevent them from dying from starvation, alarming physiological alterations might occur. Future studies are needed to assess how such a condition can affect wild populations, as well as possible sublethal consequences that could impact their long-term survival.

Living naked: first case of lack of skin-related structures in an elasmobranch, the blackmouth catshark (Galeus melastomus)

As far as is known, in this paper the first case of lacking of skin-related structures (epidermis, stratum laxum, dermal denticles and teeth) in a free-swimming elasmobranch, the blackmouth catshark, Galeus melastomus, is reported. The individual was caught by trawl in Sardinian waters (central-western Mediterranean) in July 2019 at a depth of 500 m. Although this kind of morphological abnormality is potentially fatal, the observations suggested that the specimen was in good health and well developed.

Ultrasonographic and hormonal characterization of reproductive health and disease in wild, semiwild, and aquarium-housed southern stingrays (Hypanus americanus)

OBJECTIVE

To characterize physical examination, plasma biochemical, and ultrasonographic findings in aquarium-housed, managed semiwild, and wild southern stingrays (Hypanus americanus) with and without reproductive disease.

ANIMALS

Southern stingrays from aquarium (n = 48), lagoon (managed semiwild; 34), and wild (12) habitats.

PROCEDURES

Limited, opportunistic prosections were performed of presumed anatomically normal wild southern stingrays and compared with findings for aquarium-housed stingrays with reproductive disease. Ultrasonographic video data from both groups were used to assign a score (1 to 5) indicating increasing severity of ovarian and uterine reproductive disease. Plasma total 17β-estradiol, estrone, progesterone, and testosterone concentrations were measured with enzyme immunoassays validated for use in southern stingrays.

RESULTS

Ultrasonographic ovarian scores were significantly correlated with uterine scores. No reproductive disease was detected in semiwild or wild stingrays, but 65% (31/48) of aquarium-housed stingrays had developing or advanced reproductive disease (ie, ultrasonographic ovarian or uterine score of 4 or 5). Significant correlations were identified between ovarian and uterine disease status and plasma concentrations of all steroid hormones except testosterone.

CONCLUSIONS AND CLINICAL RELEVANCE

Findings suggested that ultrasonography and plasma hormone concentrations may be useful in the identification of reproductive disease and determination of disease severity in southern stingrays.

Genetic and morphological characterization of Mawsonascaris vulvolacinata n. sp. (Nematoda: Anisakidae) and associated histopathology in a wild caught cowtail stingray, Pastinachus ater

There are limited reports of infectious agents affecting Australian cowtail stingrays. In the present study, a new species of ascaridoid nematode belonging to the genus Mawsonascaris is described. The most distinct characteristic features were observed in females (the presence of a polar spine in the eggs and a flap-like projection in the vulval area). An identification key for Mawsonascaris spp. is provided. Additionally, internal transcribed spacers (ITS) sequences were obtained for the new species. Alignment of the ITS sequence of the specimens in the present study with those deposited in GenBank showed that there exists no other highly similar sequence. Phylogenetic analyses resulted in a distinct grouping of our specimens supporting morphological distinction from previously described Mawsonascaris spp. Histology was used to investigate the pathology caused by the infection. Necrosis, inflammation and fibrosis were evident at the border of the nodules formed by parasite. A large number of parasites were present in muscularis mucosae and submucosa but not in the muscularis of the stomach. The parasites were associated with an increased inflammatory response, which was also found in the muscularis mucosae and submucosa. Similar pathology has been described in elasmobranchs infected by cestodes, although with more severe lesions.

Parasites of cartilaginous fishes (Chondrichthyes) in South Africa - a neglected field of marine science

Southern Africa is considered one of the world's 'hotspots' for the diversity of cartilaginous fishes (Chondrichthyes), with currently 204 reported species. Although numerous literature records and treatises on chondrichthyan fishes are available, a paucity of information exists on the biodiversity of their parasites. Chondrichthyan fishes are parasitised by several groups of protozoan and metazoan organisms that live either permanently or temporarily on and within their hosts. Reports of parasites infecting elasmobranchs and holocephalans in South Africa are sparse and information on most parasitic groups is fragmentary or entirely lacking. Parasitic copepods constitute the best-studied group with currently 70 described species (excluding undescribed species or nomina nuda) from chondrichthyans. Given the large number of chondrichthyan species present in southern Africa, it is expected that only a mere fraction of the parasite diversity has been discovered to date and numerous species await discovery and description. This review summarises information on all groups of parasites of chondrichthyan hosts and demonstrates the current knowledge of chondrichthyan parasites in South Africa. Checklists are provided displaying the host-parasite and parasite-host data known to date.

Multi-locus sequence typing provides epidemiological insights for diseased sharks infected with fungi belonging to the Fusarium solani species complex

Fusarium spp. are saprobic moulds that are responsible for severe opportunistic infections in humans and animals. However, we need epidemiological tools to reliably trace the circulation of such fungal strains within medical or veterinary facilities, to recognize environmental contaminations that might lead to infection and to improve our understanding of factors responsible for the onset of outbreaks. In this study, we used molecular genotyping to investigate clustered cases of Fusarium solani species complex (FSSC) infection that occurred in eight Sphyrnidae sharks under managed care at a public aquarium. Genetic relationships between fungal strains were determined by multi-locus sequence typing (MLST) analysis based on DNA sequencing at five loci, followed by comparison with sequences of 50 epidemiologically unrelated FSSC strains. Our genotyping approach revealed that F. keratoplasticum and F. solani haplotype 9x were most commonly isolated. In one case, the infection proved to be with another Hypocrealian rare opportunistic pathogen Metarhizium robertsii. Twice, sharks proved to be infected with FSSC strains with the same MLST sequence type, supporting the hypothesis the hypothesis that common environmental populations of fungi existed for these sharks and would suggest the longtime persistence of the two clonal strains within the environment, perhaps in holding pools and life support systems of the aquarium. This study highlights how molecular tools like MLST can be used to investigate outbreaks of microbiological disease. This work reinforces the need for regular controls of water quality to reduce microbiological contamination due to waterborne microorganisms.

Enucleation in a Cownose Ray (Rhinoptera bonasus)

Trauma is a common problem in Cownose Ray during mating season in both wild and captive rays. Enucleation is indicated when there is an ocular trauma. A 5-year-old female Cownose Ray (Rhinoptera bonasus) from Aquaria of Kuala Lumpur Convention Centre (KLCC) was presented to University Veterinary Hospital (UVH), Universiti Putra Malaysia, with a complaint of protruding left eye, which resulted from crushing into artificial coral during mating season. There were a hyphema in the traumatic left eye, periorbital tissue tear, exposed left eye socket, and multiple abrasions on both pectoral fins. The Cownose was anaesthetized and maintained with isoeugenol and on-field emergency enucleation of the left eye was performed. It was managed medically with postoperative enrofloxacin, tobramycin ointment, and povidone iodine. No suture breakdown and secondary infection were observed at day 7 after enucleation during revisit. At day 24 after enucleation, the Cownose responded well to treatment with excellent healing progression and no surgical complication was observed.

Therapeutic Contraindications in Exotic Pets

The selection and dosing of medications for exotic pets are often challenging because most drugs are used in an extralabel manner without pharmacokinetic and pharmacodynamic studies. Doses are often extrapolated from common domestic animals and safety data are often lacking in exotic species. Just as the bioavailability and therapeutic levels are different for each species, what may be a safe and commonly used medication in one species can be deadly in another. Various drugs with documented contraindications in certain exotic pet species are outlined in this review and the pathophysiology, clinical signs, and treatment options are described when applicable.

Microscopic and Molecular Evidence of the First Elasmobranch Adomavirus, the Cause of Skin Disease in a Giant Guitarfish, Rhynchobatus djiddensis

Only eight families of double-stranded DNA (dsDNA) viruses are known to infect vertebrate animals. During an investigation of papillomatous skin disease in an elasmobranch species, the giant guitarfish (Rhynchobatus djiddensis), a novel virus, distinct from all known viral families in regard to particle size, morphology, genome organization, and helicase phylogeny was discovered. Large inclusion bodies containing 75-nm icosahedral viral particles were present within epithelial cell nuclei in the proliferative skin lesions. Deep metagenomic sequencing revealed a 22-kb circular dsDNA viral genome, tentatively named guitarfish "adomavirus" (GAdoV), with only distant homology to two other fish viruses, Japanese eel endothelial cell-infecting virus (JEECV) and a recently reported marbled eel virus. Phylogenetic analysis of the helicase domain places the guitarfish virus in a novel clade that is equidistant between members of the Papillomaviridae and Polyomaviridae families. Specific PCR, quantitative PCR, and in situ hybridization were used to detect, quantify, and confirm that GAdoV DNA was localized to affected epithelial cell nuclei. Changes in the viral titer, as well as the presence of a hybridization signal, coincided with the progression and then final resolution of gross and microscopic lesions. The results indicate that GAdoV is the causative agent of the proliferative skin lesions.IMPORTANCE Cartilaginous fish, including the sharks and rays, evolved from ancestral fish species at least 400 million years ago. Even though they are the descendants of one of the most ancient vertebrate lineages, reports of viral diseases in these species are rare and poorly documented. Deep sequencing revealed a highly divergent virus, tentatively named guitarfish adomavirus, that is distantly related to known papillomaviruses and polyomaviruses. Out of the eight predicted viral genes, only the helicase could be identified as viral by sequence homology searches (BLAST), exemplifying the difficulties of discovering novel viruses within seas of unidentifiable "dark matter" associated with deep sequencing data. The novel adomavirus represents the first viral genome shown to cause clinical disease in a cartilaginous fish species, the giant guitarfish. Our findings demonstrate that emerging fish viruses are fertile ground to expand our understanding of viral evolution in vertebrates.

Considerations for Treatment of Large Zoologic Collections: Fish

Aquatic species live most or all their lives in water; therefore, the health of the environment is intimately connected to their health and medical care. Understanding and maintaining appropriate husbandry and nutrition for the housed aquarium species are essential to sustain health. Most diseases of fish are secondary opportunistic infections; prevention and early diagnosis are recommended. Treatments involve environmental and/or nutritional management first, followed by targeted pharmacologic treatment to control a specific pathogen. Pharmacokinetic research evaluating the effects and safety of medications in fish are greatly needed in the peer-reviewed literature.

Locally extensive meningoencephalitis caused by Miamiensis avidus (syn. Philasterides dicentrarchi) in a zebra shark

Scuticociliatosis, caused by ciliated protozoa in the subclass Scuticociliatia of the phylum Ciliophora, can cause fatal disease in teleost fish species. However, information on scuticociliatosis in elasmobranchs is still scarce. In this report, we describe a case of locally extensive meningoencephalitis caused by Miamiensis avidus (syn. Philasterides dicentrarchi) in a 2 yr old captive zebra shark Stegostoma fasciatum. Granulocytic meningoencephalitis was observed through histological assessment. Inflammation was confined to the ventral aspect of the brain with a large number of ciliated protozoa, transforming into non-suppurative meningitis in the lateral aspect, and gradually vanished in the dorsal aspect. No histopathological and polymerase chain reaction (PCR) evidence of systemic dissemination of M. avidus was found. PCR targeting the gene coding the small-subunit ribosomal RNA (SSUrRNA) of M. avidus was performed on the brain, liver, and gill tissues, and only brain tissue yielded a positive result. The DNA sequences from amplicons of the protozoal SSUrRNA gene were completely matched to that of M. avidus. The distribution of protozoa in the current case was mainly located in the brain and suggests the possibility of a direct neural invasive pathway of M. avidus through the nasal cavity/ampullary system and/or a unique tissue tropism of M. avidus specific to the brain in zebra sharks. Further investigations on the pathogenesis of M. avidus in elasmobranchs, especially zebra sharks, are needed.

Acute disseminated mycobacteriosis in captive Atlantic guitarfish (Rhinobatos lentiginosus)

An adult female captive-born Atlantic guitarfish ( Rhinobatos lentiginosus) was found acutely moribund on exhibit and died soon after presentation. Abnormalities on autopsy were focal cutaneous erythema on the tail, a small liver, many variably sized friable ovarian follicles, and coelomic effusion. Histologic examination revealed systemic bacterial embolization, and yolk coelomitis with minimal associated inflammation and some mineralization. Bacterial culture of blood and coelomic effusion grew a rapidly growing Mycobacterium species that was further identified as Mycobacterium chelonae by PCR amplification and sequencing of the RNA polymerase subunit beta ( rpoB) gene of isolated genomic DNA. Concurrent reproductive disease may have caused immunosuppression, thus predisposing to the mycobacterial infection. At another institution, an adult male wild-caught Atlantic guitarfish was found dead on exhibit with no premonitory signs. Abnormalities on autopsy were a thin body condition, small liver, and coelomic effusion. Histologic examination revealed acute mycobacterial septicemia. M. chelonae was also identified in this fish by PCR amplification and sequencing. Mycobacteriosis has rarely been reported in captive elasmobranchs. Guitarfish may have greater susceptibility to mycobacteriosis than other elasmobranchs, and acute and chronic manifestations of the disease may exist in this species.

Infection of the lesser spotted dogfish with Proleptus obtusus Dujardin, 1845 (Nematoda: Spirurida) reflects ontogenetic feeding behaviour and seasonal differences in prey availability

Proleptus obtusus Dujardin, 1845 is the most common parasite infecting the gut of the lesser spotted dogfish (Scyliorhinus canicula, Linnaeus). This nematode is trophically transmitted from an intermediate crustacean host to the definitive elasmobranch host. Sexual and age-related differences in habitat occupancy and feeding behaviour of the lesser spotted dogfish make this parasite-host dyad ideal for testing which aspects of host biology influence parasite transmission. Here, the relationship between P. obtusus burden and host condition, sex and age were investigated in lesser spotted dogfish captured in the Northeast Atlantic. Prevalence of P. obtusus was of 94.8% with a mean abundance of 23.3 worms per host. Our results indicate that parasite burden is best explained by the interaction between ontogenetic differences in foraging behaviour of the lesser spotted dogfish and seasonal differences in prey availability.