Drivers of infection with Toxoplasma gondii genotype type II in Eurasian red squirrels (Sciurus vulgaris)

BACKGROUND

In September 2014, there was sudden upsurge in the number of Eurasian red squirrels (Sciurus vulgaris) found dead in the Netherlands. High infection levels with the parasite Toxoplasma gondii were demonstrated, but it was unclear what had caused this increase in cases of fatal toxoplasmosis. In the present study, we aimed to gain more knowledge on the pathology and prevalence of T. gondii infections in Eurasian red squirrels in the Netherlands, on the T. gondii genotypes present, and on the determinants of the spatiotemporal variability in these T. gondii infections. The presence of the closely related parasite Hammondia hammondi was also determined.

METHODS

Eurasian red squirrels that were found dead in the wild or that had died in wildlife rescue centres in the Netherlands over a period of seven years (2014-2020) were examined. Quantitative real-time polymerase chain reaction was conducted to analyse tissue samples for the presence of T. gondii and H. hammondi DNA. Toxoplasma gondii-positive samples were subjected to microsatellite typing and cluster analysis. A mixed logistic regression was used to identify climatic and other environmental predictors of T. gondii infection in the squirrels.

RESULTS

A total of 178 squirrels were examined (49/178 T. gondii positive, 5/178 H. hammondi positive). Inflammation of multiple organs was the cause of death in 29 squirrels, of which 24 were also T. gondii polymerase chain reaction positive. Toxoplasma gondii infection was positively associated with pneumonia and hepatitis. Microsatellite typing revealed only T. gondii type II alleles. Toxoplasma gondii infection rates showed a positive correlation with the number of days of heavy rainfall in the previous 12 months. Conversely, they showed a negative association with the number of hot days within the 2-week period preceding the sampling date, as well as with the percentage of deciduous forest cover at the sampling site.

CONCLUSIONS

Toxoplasma gondii infection in the squirrels appeared to pose a significant risk of acute mortality. The T. gondii genotype detected in this study is commonly found across Europe. The reasons for the unusually high infection rates and severe symptoms of these squirrels from the Netherlands remain unclear. The prevalence of T. gondii in the deceased squirrels was linked to specific environmental factors. However, whether the increase in the number of dead squirrels indicated a higher environmental contamination with T. gondii oocysts has yet to be established.

High prevalence and genetic diversity of Treponema paraluisleporidarum isolates in European lagomorphs

IMPORTANCE

Syphilis is an ancient disease of humans and lagomorphs caused by two distinct but genetically closely related bacteria (>98% sequence identity based on the whole genome) of the genus Treponema. While human syphilis is well studied, little is known about the disease in the lagomorph host. Yet, comparative studies are needed to understand mechanisms in host-pathogen coevolution in treponematoses. Importantly, Treponema paraluisleporidarum-infected hare populations provide ample opportunity to study the syphilis-causing pathogen in a naturally infected model population without antibiotic treatment, data that cannot be obtained from syphilis infection in humans. We provide data on genetic diversity and are able to highlight various types of repetitions in one of the two hypervariable regions at the tp0548 locus that have not been described in the human syphilis-causing sister bacterium Treponema pallidum subsp. pallidum.

Diagnosis and treatment of a congenital portosystemic shunt in a ferret (Mustela putorius furo)

A 3-year-old female neutered ferret presented with progressive weight loss was diagnosed with portosystemic shunting based on increased fasting bile acids, rectal ammonia tolerance testing and advanced imaging. Ammonia reference values were determined in 16 healthy ferrets. A congenital extrahepatic spleno-caval shunt was visualised with ultrasonography and CT angiography of the abdomen. Complete surgical shunt closure by suture ligation was performed, without clinical improvement after surgery. Euthanasia was elected 4 months postoperatively because the clinical condition deteriorated. This is a case report of advanced diagnostics and surgical treatment of a congenital extrahepatic portosystemic shunt in a ferret, demonstrating rectal ammonia tolerance testing and imaging as feasible techniques for the diagnosis.

Harbor Porpoise Deaths Associated with Erysipelothrix rhusiopathiae, the Netherlands, 2021

In August 2021, a large-scale mortality event affected harbor porpoises (Phocoena phocoena) in the Netherlands. Pathology and ancillary testing of 22 animals indicated that the most likely cause of death was Erysipelothrix rhusiopathiae infection. This zoonotic agent poses a health hazard for cetaceans and possibly for persons handling cetacean carcasses.

Gross, Histologic and Immunohistochemical Characteristics of Keratoacanthomas in Lizards

The present study describes the clinical behavior as well as the histopathologic and immunohistochemical characteristics of keratoacanthomas (Kas) in three different saurian species. While Kas presented as two dermal lesions in a bearded dragon (Pogona vitticeps), multicentric Kas were observed in three panther chameleons (Furcifer pardalis) and a veiled chameleon (Chamaeleo calyptratus). Macroscopically, Kas presented as dome-shaped skin tumors with a centralized keratinous pearl and a diameter ranging from 0.1-1.5 cm. In all lizards, Kas were predominantly located at the dorsolateral body wall, and KA of the eyelid was additionally observed in three out of four chameleons. Histologically, KAs presented as relatively well-defined, circumscribed epidermal proliferations that consisted of a crateriform lesion containing a central keratinous pearl with minimally infiltrating borders. In all KAs, a consistent immunohistochemical pattern was observed, with the expression of cyclooxygenase-2, E-cadherin, and pan-cytokeratin. A follow-up period of one to two years was established in all lizards. While no recurrence was observed in the panther chameleons, recurrence of a single keratoacanthoma was observed in the bearded dragon after one year, and in the veiled chameleon, multicentric keratoacanthomas reappeared during a follow-up period of two years. We describe KA as a previously unrecognized neoplastic entity in lizards that constitutes a low-grade, non-invasive but rapidly growing skin tumor that may show a multicentric appearance, especially in chameleons. As previously postulated for dermal squamous cell carcinomas (SCC), artificial ultraviolet lighting may play an important role in the oncogenesis of KAs in lizards. Although dermal SCCs in lizards show similar predilection sites and gross pathologic features, our results suggest that KA should be considered as a histologic variant of SCC that represents a rather benign squamous proliferation in comparison to conventional SCCs. Early diagnosis of KA and reliable discrimination from SCCs are essential for the prognosis of this neoplastic entity in lizards.

Evidence of Hearing Loss and Unrelated Toxoplasmosis in a Free-Ranging Harbour Porpoise (Phocoena phocoena)

Simple Summary

Evidence of hearing impairment was identified in a female harbour porpoise (Phocoena phocoena) on the basis of inner ear analysis. The animal live stranded on the Dutch coast at Domburg in 2016 and died a few hours later. Ultrastructural examination of the inner ear revealed evidence of sensory cell loss, which is compatible with noise exposure. In addition, histopathology also revealed multifocal necrotising protozoal encephalitis. A diagnosis of toxoplasmosis was confirmed by positive staining of tissue with anti-Toxoplasma gondii antibodies; however, T. gondii tachyzoites were not observed histologically in any of the examined tissues. This is the first case of presumptive noise-induced hearing loss and demonstration of T. gondii cysts in the brain of a free-ranging harbour porpoise from the North Sea.

Abstract

Evidence of hearing impairment was identified in a harbour porpoise (Phocoena phocoena) on the basis of scanning electron microscopy. In addition, based on histopathology and immunohistochemistry, there were signs of unrelated cerebral toxoplasmosis. The six-year old individual live stranded on the Dutch coast at Domburg in 2016 and died a few hours later. The most significant gross lesion was multifocal necrosis and haemorrhage of the cerebrum. Histopathology of the brain revealed extensive necrosis and haemorrhage in the cerebrum with multifocal accumulations of degenerated neutrophils, lymphocytes and macrophages, and perivascular lymphocytic cuffing. The diagnosis of cerebral toxoplasmosis was confirmed by positive staining of protozoa with anti-Toxoplasma gondii antibodies. Tachyzoites were not observed histologically in any of the examined tissues. Ultrastructural evaluation of the inner ear revealed evidence of scattered loss of outer hair cells in a 290 µm long segment of the apical turn of the cochlea, and in a focal region of ~ 1.5 mm from the apex of the cochlea, which was compatible with noise-induced hearing loss. This is the first case of concurrent presumptive noise-induced hearing loss and toxoplasmosis in a free-ranging harbour porpoise from the North Sea.

What a stranded whale with scoliosis can teach us about human idiopathic scoliosis

Scoliosis is a deformation of the spine that may have several known causes, but humans are the only mammal known to develop scoliosis without any obvious underlying cause. This is called 'idiopathic' scoliosis and is the most common type. Recent observations showed that human scoliosis, regardless of its cause, has a relatively uniform three-dimensional anatomy. We hypothesize that scoliosis is a universal compensatory mechanism of the spine, independent of cause and/or species. We had the opportunity to study the rare occurrence of scoliosis in a whale (Balaenoptera acutorostrata) that stranded in July 2019 in the Netherlands. A multidisciplinary team of biologists, pathologists, veterinarians, taxidermists, radiologists and orthopaedic surgeons conducted necropsy and imaging analysis. Blunt traumatic injury to two vertebrae caused an acute lateral deviation of the spine, which had initiated the development of compensatory curves in regions of the spine without anatomical abnormalities. Three-dimensional analysis of these compensatory curves showed strong resemblance with different types of human scoliosis, amongst which idiopathic. This suggests that any decompensation of spinal equilibrium can lead to a rather uniform response. The unique biomechanics of the upright human spine, with significantly decreased rotational stability, may explain why only in humans this mechanism can be induced relatively easily, without an obvious cause, and is therefore still called 'idiopathic'.

Challenges in the Assessment of Bycatch: Postmortem Findings in Harbor Porpoises (Phocoena phocoena) Retrieved From Gillnets

Bycatch is considered one of the most significant threats affecting cetaceans worldwide. In the North Sea, bottom-set gillnets are a specific risk for harbor porpoises (Phocoena phocoena). Methods to estimate bycatch rates include on-board observers, remote electronic monitoring, and fishermen voluntarily reporting; none of these are systematically conducted. Additionally, necropsies of stranded animals can provide insights into bycatch occurrence and health status of individuals. There are, however, uncertainties when it comes to the assessment of bycatch in stranded animals, mainly due to the lack of diagnostic tools specific for underwater entrapment. We conducted a literature review to establish criteria that aid in the assessment of bycatch in small cetaceans, and we tested which of these criteria applied to harbor porpoises retrieved from gillnets in the Netherlands (n = 12). Twenty-five criteria were gathered from literature. Of these, "superficial incisions," "encircling imprints," and "recent ingestion of prey" were observed in the vast majority of our confirmed bycatch cases. Criteria like "pulmonary edema," "pulmonary emphysema," and "organ congestion" were also frequently observed, although considered unspecific as an indicator of bycatch. Notably, previously mentioned criteria as "favorable health status," "absence of disease," or "good nutritional condition" did not apply to the majority of our bycaught porpoises. This may reflect an overall reduced fitness of harbor porpoises inhabiting the southern North Sea or a higher chance of a debilitated porpoise being bycaught, and could result in an underestimation of bycatch rates when assessing stranded animals.

Pathological Findings in White-Beaked Dolphins (Lagenorhynchus albirostris) and Atlantic White-Sided Dolphins (Lagenorhynchus acutus) From the South-Eastern North Sea

In the North Sea, white-beaked dolphins (Lagenorhynchus albirostris) occur regularly and are the second most common cetacean in the area, while their close relative, the Atlantic white-sided dolphin (Lagenorhynchus acutus), prefers the deeper waters of the northern North Sea and adjacent Atlantic Ocean. Though strandings of both species have occurred regularly in the past three decades, they have decreased in the southern North Sea during the last years. Studies describing necropsy findings in stranded Lagenorhynchus spp. are, to date, still scarce, while information gained through post-mortem examinations may reveal valuable information about underlying causes of this decline, including age structure and the reproduction status. Therefore, we retrospectively assessed and compared the necropsy results from fresh Lagenorhynchus spp. stranded along the southeastern North Sea between 1990 and 2019. A full necropsy was performed on 24 white-beaked dolphins and three Atlantic white-sided dolphins from the German and Dutch coast. Samples of selected organs were taken for histopathological, bacteriological, mycological, parasitological and virological examinations. The most common post-mortem findings were emaciation, gastritis and pneumonia. Gastritis and ulceration of the stomach was often associated with an anisakid nematode infection. Pneumonia was most likely caused by bacterial infections. Encephalitis was observed in three animals and morbillivirus antigen was detected immunohistochemically in one case. Although the animal also showed pneumonic lesions, virus antigen was only found in the brain. Parasitic infections mainly affected the gastro-intestinal tract. Lungworm infections were only detected in two cases and no associations with pathological alterations were observed. Stenurus spp. were identified in two of three cases of parasitic infections of the ears. Twelve of the 26 white-beaked dolphins stranded in Germany were found between 1993 and 1994, but there was no evidence of epizootic disease events or mass strandings during the monitored period.

Forensic microbiology reveals that Neisseria animaloris infections in harbour porpoises follow traumatic injuries by grey seals

Neisseria animaloris is considered to be a commensal of the canine and feline oral cavities. It is able to cause systemic infections in animals as well as humans, usually after a biting trauma has occurred. We recovered N. animaloris from chronically inflamed bite wounds on pectoral fins and tailstocks, from lungs and other internal organs of eight harbour porpoises. Gross and histopathological evidence suggest that fatal disseminated N. animaloris infections had occurred due to traumatic injury from grey seals. We therefore conclude that these porpoises survived a grey seal predatory attack, with the bite lesions representing the subsequent portal of entry for bacteria to infect the animals causing abscesses in multiple tissues, and eventually death. We demonstrate that forensic microbiology provides a useful tool for linking a perpetrator to its victim. Moreover, N. animaloris should be added to the list of potential zoonotic bacteria following interactions with seals, as the finding of systemic transfer to the lungs and other tissues of the harbour porpoises may suggest a potential to do likewise in humans.

Local controlled release of corticosteroids extends surgically induced joint instability by inhibiting tissue healing

Background and Purpose

Corticosteroids are intra‐articularly injected to relieve pain in joints with osteoarthritis (OA) or acute tissue damage such as ligament or tendon tears, despite its unverified contraindication in unstable joints. Biomaterial‐based sustained delivery may prolong reduction of inflammatory pain, while avoiding harmful peak drug concentrations.

Experimental Approach

The applicability of prolonged corticosteroid exposure was examined in a rat model of anterior cruciate ligament and medial meniscus transection (ACLT + pMMx) with ensuing degenerative changes.

Key Results

Intra‐articular injection of a bolus of the corticosteroid triamcinolone acetonide (TAA) resulted in enhanced joint instability in 50% of the joints, but neither instability‐induced OA cartilage degeneration, synovitis, nor the OA‐related bone phenotype was affected. However, biomaterial microsphere‐based extended TAA release enhanced instability in 94% of the animals and induced dystrophic calcification and exacerbation of cartilage degeneration. In healthy joints, injection with TAA releasing microspheres had no effect at all. In vitro, TAA inhibited cell migration out of joint tissue explants, suggesting inhibited tissue healing in vivo as mechanisms for enhanced instability and subsequent cartilage degeneration.

Conclusions and Implications

We conclude that short‐term TAA exposure has minor effects on surgically induced unstable joints, but its extended presence is detrimental by extending instability and associated joint degeneration through compromised healing. This supports a contraindication of prolonged corticosteroid exposure in tissue damage‐associated joint instability, but not of brief exposure.

Controlled release of celecoxib inhibits inflammation, bone cysts and osteophyte formation in a preclinical model of osteoarthritis

Major hallmarks of osteoarthritis (OA) are cartilage degeneration, inflammation and osteophyte formation. COX-2 inhibitors counteract inflammation-related pain, but their prolonged oral use entails the risk for side effects. Local and prolonged administration in biocompatible and degradable drug delivery biomaterials could offer an efficient and safe treatment for the long-term management of OA symptoms. Therefore, we evaluated the disease-modifying effects and the optimal dose of polyesteramide microspheres delivering the COX-2 inhibitor celecoxib in a rat OA model. Four weeks after OA induction by anterior cruciate ligament transection and partial medial meniscectomy, 8-week-old female rats (n = 6/group) were injected intra-articular with celecoxib-loaded microspheres at three dosages (0.03, 0.23 or 0.39 mg). Unloaded microspheres served as control. During the 16-week follow-up, static weight bearing and plasma celecoxib concentrations were monitored. Post-mortem, micro-computed tomography and knee joint histology determined progression of synovitis, osteophyte formation, subchondral bone changes, and cartilage integrity. Systemic celecoxib levels were below the detection limit 6 days upon delivery. Systemic and local adverse effects were absent. Local delivery of celecoxib reduced the formation of osteophytes, subchondral sclerosis, bone cysts and calcified loose bodies, and reduced synovial inflammation, while cartilage histology was unaffected. Even though the effects on pain could not be evualated directly in the current model, our results suggest the application of celecoxib-loaded microspheres holds promise as novel, safe and effective treatment for inflammation and pain in OA.

Complete Genome Sequence of Frog virus 3, Isolated from a Strawberry Poison Frog (Oophaga pumilio) Imported from Nicaragua into the Netherlands

Frog virus 3 was isolated from a strawberry poison frog (Oophaga pumilio) imported from Nicaragua via Germany to the Netherlands, and its complete genome sequence was determined. Frog virus 3 isolate Op/2015/Netherlands/UU3150324001 is 107,183 bp long and has a nucleotide similarity of 98.26% to the reference Frog virus 3 isolate.

Investigation of Amphibian Mortality Events in Wildlife Reveals an On-Going Ranavirus Epidemic in the North of the Netherlands

In the four years following the first detection of ranavirus (genus Ranavirus, family Iridoviridae) infection in Dutch wildlife in 2010, amphibian mortality events were investigated nationwide to detect, characterize and map ranaviruses in amphibians over time, and to establish the affected host species and the clinico-pathological presentation of the disease in these hosts. The ultimate goal was to obtain more insight into ranavirus disease emergence and ecological risk. In total 155 dead amphibians from 52 sites were submitted between 2011 and 2014, and examined using histopathology, immunohistochemistry, virus isolation and molecular genetic characterization. Ranavirus-associated amphibian mortality events occurred at 18 sites (35%), initially only in proximity of the 2010 index site. Specimens belonging to approximately half of the native amphibian species were infected, including the threatened Pelobates fuscus (spadefoot toad). Clustered massive outbreaks involving dead adult specimens and ranavirus genomic identity indicated that one common midwife toad virus (CMTV)-like ranavirus strain is emerging in provinces in the north of the Netherlands. Modelling based on the spatiotemporal pattern of spread showed a high probability that this emerging virus will continue to be detected at new sites (the discrete reproductive power of this outbreak is 0.35). Phylogenetically distinct CMTV-like ranaviruses were found in the south of the Netherlands more recently. In addition to showing that CMTV-like ranaviruses threaten wild amphibian populations not only in Spain but also in the Netherlands, the current spread and risk of establishment reiterate that understanding the underlying causes of CMTV-like ranavirus emergence requires international attention.

Disseminated Mycobacterium intracellulare infection in a broad-snouted caiman Caiman latirostris

A 10 yr old broad-snouted caiman Caiman latirostris from a small Dutch animal park was presented with long-term variable periods of anorexia and weight loss. Blood chemistry showed slightly elevated uric acid levels and low ionised calcium concentration. Ultrasonographical thickening of the intestinal wall in the region of the duodenum was evident. Pathological changes were a thickening of the wall of 90% of the small intestines, enlarged spleen with multifocal white foci and an enlarged light-brown liver. Histopathological lesions consisted of disseminated granulomas in the intestinal wall, the liver and the spleen. Multinucleated giant cells and epitheloid macrophages were abundant. Ziehl-Neelsen staining showed numerous intralesional acid-fast bacteria. Polymerase chain reaction for Mycobacterium intracellulare was positive.

Heat shock protein expression analysis in canine osteosarcoma reveals HSP60 as a potentially relevant therapeutic target

Heat shock proteins (HSP) are highly conserved across eukaryotic and prokaryotic species. These proteins play a role in response to cellular stressors, protecting cells from damage and facilitating recovery. In tumor cells, HSPs can have cytoprotective effects and interfere with apoptotic cascades. This study was performed to assess the prognostic and predictive values of the gene expression of HSP family members in canine osteosarcoma (OS) and their potential for targeted therapy. Gene expressions for HSP were assessed using quantitative PCR (qPCR) on 58 snap-frozen primary canine OS tumors and related to clinic-pathological parameters. A significant increased expression of HSP60 was found in relation to shorter overall survival and an osteoblastic phenotype. Therefore, the function of HSP60 was investigated in more detail. Immunohistochemical analysis revealed heterogeneous staining for HSP60 in tumors. The highest immunoreactivity was found in tumors of short surviving dogs. Next HSP expression was shown in a variety of canine and human OS cell lines by qPCR and Western blot. In two highly metastatic cell lines HSP60 expression was silenced using siRNA resulting in decreased cell proliferation and induction of apoptosis in both cell lines. It is concluded that overexpression of HSP60 is associated with a poor prognosis of OS and should be evaluated as a new target for therapy.

The effect of interleukin-2 on canine peripheral nerve sheath tumours after marginal surgical excision: a double-blind randomized study

Background

The objective of this study was to evaluate the effect on outcomes of intraoperative recombinant human interleukin-2 injection after surgical resection of peripheral nerve sheath tumours. In this double-blind trial, 40 patients due to undergo surgical excision (<5 mm margins) of presumed peripheral nerve sheath tumours were randomized to receive intraoperative injection of interleukin-2 or placebo into the wound bed.

Results

There were no significant differences in any variable investigated or in median survival between the two groups. The median recurrence free interval was 874 days (range 48–2141 days), The recurrence-free interval and overall survival time were significantly longer in dogs that undergone the primary surgery by a specialist-certified surgeon compared to a referring veterinarian regardless of whether additional adjunct therapy was given.

Conclusion

Overall, marginal excision of peripheral nerve sheath tumours in dogs resulted in a long survival time, but adjuvant treatment with recombinant human interleukin-2 (rhIL-2) did not provide a survival advantage.

Of mice, men and elephants: the relation between articular cartilage thickness and body mass

Mammalian articular cartilage serves diverse functions, including shock absorption, force transmission and enabling low-friction joint motion. These challenging requirements are met by the tissue’s thickness combined with its highly specific extracellular matrix, consisting of a glycosaminoglycan-interspersed collagen fiber network that provides a unique combination of resilience and high compressive and shear resistance. It is unknown how this critical tissue deals with the challenges posed by increases in body mass. For this study, osteochondral cores were harvested post-mortem from the central sites of both medial and lateral femoral condyles of 58 different mammalian species ranging from 25 g (mouse) to 4000 kg (African elephant). Joint size and cartilage thickness were measured and biochemical composition (glycosaminoclycan, collagen and DNA content) and collagen cross-links densities were analyzed. Here, we show that cartilage thickness at the femoral condyle in the mammalian species investigated varies between 90 µm and 3000 µm and bears a negative allometric relationship to body mass, unlike the isometric scaling of the skeleton. Cellular density (as determined by DNA content) decreases with increasing body mass, but gross biochemical composition is remarkably constant. This however need not affect life-long performance of the tissue in heavier mammals, due to relatively constant static compressive stresses, the zonal organization of the tissue and additional compensation by joint congruence, posture and activity pattern of larger mammals. These findings provide insight in the scaling of articular cartilage thickness with body weight, as well as in cartilage biochemical composition and cellularity across mammalian species. They underscore the need for the use of appropriate in vivo models in translational research aiming at human applications.

Nuclear DNA-Content in Mesenchymal Lesions in Dogs: Its Value as Marker of Malignancy and Extent of Genomic Instability

DNA-aneuploidy may reflect the malignant nature of mesenchymal proliferations and herald gross genomic instability as a mechanistic factor in tumor genesis. DNA-ploidy and -index were determined by flow cytometry in canine inflammatory or neoplastic mesenchymal tissues and related to clinico-pathological features, biological behavior and p53 gene mutational status. Half of all sarcomas were aneuploid. Benign mesenchymal neoplasms were rarely aneuploid and inflammatory lesions not at all. The aneuploidy rate was comparable to that reported for human sarcomas with significant variation amongst subtypes. DNA-ploidy status in canines lacked a relation with histological grade of malignancy, in contrast to human sarcomas. While aneuploidy was related to the development of metastases in soft tissue sarcomas it was not in osteosarcomas. No relation amongst sarcomas was found between ploidy status and presence of P53 gene mutations. Heterogeneity of the DNA index between primary and metastatic sarcoma sites was present in half of the cases examined. Hypoploidy is more common in canine sarcomas and hyperploid cases have less deviation of the DNA index than human sarcomas. The variation in the presence and extent of aneuploidy amongst sarcoma subtypes indicates variation in genomic instability. This study strengthens the concept of interspecies variation in the evolution of gross chromosomal aberrations during cancer development.

Comparative study of depth-dependent characteristics of equine and human osteochondral tissue from the medial and lateral femoral condyles

Articular cartilage defects are common after joint injuries. When left untreated, the biomechanical protective function of cartilage is gradually lost, making the joint more susceptible to further damage, causing progressive loss of joint function and eventually osteoarthritis (OA). In the process of translating promising tissue-engineering cartilage repair approaches from bench to bedside, pre-clinical animal models including mice, rabbits, goats, and horses, are widely used. The equine species is becoming an increasingly popular model for the in vivo evaluation of regenerative orthopaedic approaches. As there is also an increasing body of evidence suggesting that successful lasting tissue reconstruction requires an implant that mimics natural tissue organization, it is imperative that depth-dependent characteristics of equine osteochondral tissue are known, to assess to what extent they resemble those in humans. Therefore, osteochondral cores (4-8 mm) were obtained from the medial and lateral femoral condyles of equine and human donors. Cores were processed for histology and for biochemical quantification of DNA, glycosaminoglycan (GAG) and collagen content. Equine and human osteochondral tissues possess similar geometrical (thickness) and organizational (GAG, collagen and DNA distribution with depth) features. These comparable trends further underscore the validity of the equine model for the evaluation of regenerative approaches for articular cartilage.

The sea louse Lepeophtheirus acutus (Caligidae, Siphonostomatoida, Copepoda) as a pathogen of aquarium-held elasmobranchs

Lepeophtheirus acutus Heegaard, 1943 (Caligidae, Siphonostomatoida, Copepoda), was collected from or observed on four of six elasmobranch species held at Burgers' Zoo (Arnhem, The Netherlands). Circumstantial evidence suggested that a zebra shark, Stegostoma fasciatum (Hermann), from the wild carried the infection into the facility, where copepods reproduced and colonized additional hosts. Copepods typically attached on and about the eyes, in the mouth and occasionally about the cloaca and on the claspers. Severe ocular lesions were associated with infections on zebra sharks, a grey reef shark, Carcharhinus amblyrhynchos (Bleeker), whitetip reef sharks, Triaenodon obesus (Rüppell), and giant shovelnose ray, Rhinobatos typus Bennett, while blacktip reef sharks, Carcharhinus melanopterus (Quoy & Gaimard), and blacktip sharks, Carcharhinus limbatus (Valenciennes), living in infested aquaria showed no sign of infection. Water treatments using trichlorfon were considered primarily responsible for the eradication of copepods from hosts and infested aquaria. This case is the first report of a copepod infection being closely associated with disease and death of an aquarium-held elasmobranch. Given its ability to infect a wide variety of elasmobranchs and promote life-threatening lesions on some hosts, L. acutus should be considered a dangerous pathogen of captive elasmobranchs.

Cloaca prolapse and cystitis in green iguana (Iguana iguana) caused by a novel Cryptosporidium species

Cryptosporidium infection was associated with colitis and cystitis in 2 green iguanas (Iguana iguana). The disease was characterized by a chronic clinical course of cloacal prolapses and cystitis. Histological examination of the gut and urinary bladder showed numerous Cryptosporidium developmental stages on the surface of the epithelium with mixed inflammatory response in the lamina propria. Cryptosporidium oocysts were visualised in a cytological preparation of the faeces. Based on the small subunit ribosomal RNA gene the cryptosporidia were characterized as belonging to the intestinal cryptosporidial lineage, but not to Cryptosporidium saurophilum or Cryptosporidium serpentis species.

Association of red-mark syndrome with a Rickettsia-like organism and its connection with strawberry disease in the USA

Red-mark syndrome (RMS), a disease seen mostly in rainbow trout, Oncorhynchus mykiss, is of unknown aetiology. The research presented here indicates the presence of an intracellular bacterium in RMS-affected fish. A positive reaction was observed using immunohistochemistry (IHC) with skin lesions, liver, kidney and spleen of affected fish sampled from several locations within the United Kingdom using two different polyclonal antisera raised against Piscirickettsia salmonis. The same reaction was also seen with a number of different anti-P. salmonis monoclonal antibodies (MAbs). A disease with similar clinical signs to RMS, referred to as strawberry disease (SD), has been reported in the USA. A Rickettsia-like organism (RLO) has recently been associated with SD based on analysis of 16S rDNA sequences. Using the same panel of anti-P. salmonis antibodies used to screen the RMS samples, similar staining was obtained in tissue of SD-affected fish by IHC. A polymerase chain reaction (PCR) using RLO-specific primers was also performed on RMS-affected fish from the United Kingdom, and the samples were positive for the RLO 16S rRNA sequence. These findings suggest that the same aetiological agent may be responsible for RMS in the United Kingdom and SD in the USA.

Upper respiratory tract infection caused by Cryptosporidium baileyi in three mixed-bred falcons (Falco rusticolus x Falco cherrug)

Three mixed-bred raptors (Falco rusticolus x Falco cherrug) from a German falcon breeder were presented with a history of respiratory distress. In one bird a laryngeal stridor was noted, and oral examination revealed an epiglottal swelling. In the other two birds, nasal discharge and sneezing were the main clinical symptoms. Nasal flushing samples and biopsies were collected for pathologic, bacteriologic, and parasitologic examination. Results confirmed a cryptosporidial infection. Polymerase chain reaction (PCR) and DNA analysis identified the causative agent to be Cryptosporidium baileyi. No cryptosporidia were detected in fecal samples, indicating the infection was confined to the respiratory system. Analysis of prey animals (pigeons, quail) failed to identify the source of infection. Treatment was initiated with paromomycin in all three birds, whereas in two birds an additional therapy with azithromycin was given. However, no clinical improvement was seen after several weeks of treatment, and the birds either died or were euthanatized. To the authors' knowledge, these are the first confirmed cases of disease caused by cryptosporidia in the order of Falconiformes.

Molecular characterization of the first polyomavirus from a New World primate: squirrel monkey polyomavirus

DNA samples from a variety of New World monkeys were screened by using a broad-spectrum PCR targeting the VP1 gene of polyomaviruses. This resulted in the characterization of the first polyomavirus from a New World primate. This virus naturally infects squirrel monkeys (Saimiri sp.) and is provisionally named squirrel monkey polyomavirus (SquiPyV). The complete genome of SquiPyV is 5075 bp in length, and encodes the small T and large T antigens and the three structural proteins VP1, VP2 and VP3. Interestingly, the late region also encodes a putative agnoprotein, a feature that it shares with other polyomaviruses from humans, baboons and African green monkeys. Comparison with other polyomaviruses revealed limited sequence similarity to any other polyomavirus, and phylogenetic analysis of the VP1 gene confirmed its uniqueness.

Reovirus infections associated with high mortality in psittaciformes in The Netherlands

In The Netherlands between January 2002 and December 2004, numerous psittaciformes died showing severe splenomegaly and hepatomegaly with multifocal acute necrosis. At the start of the outbreaks mostly parakeets were affected, but later larger parrots were also involved. Seventy-eight birds showed the same features and six were examined completely, including a virological examination. Tests for polyomavirus, Pacheco's disease (herpesvirus) and circovirus psittacine beak and feather disease (PBFD) viruses and Chlamydophila psittaci were carried out. All results were negative, except for two cases of circovirus infection. Many concurrent bacterial and parasitic infections were seen. Immunohistochemistry revealed reovirus antigen in intralesional mononuclear cells, and reovirus-like particles could be observed by negative contrast electron microscopy. A reovirus was grown and the isolates reacted with polyclonal reovirus antiserum but did not react with monoclonal antibodies against chicken reovirus. The virus was therefore considered a psittacine reovirus. Because reoviruses were seen consistently, they seemed to be the most probable cause of the outbreaks. Climate, the introduction of new birds and the transportation of birds might be other factors involved in the disease seen in The Netherlands. No regional influence could be seen; therefore, we suggested that the virus might be widespread and carriers could be a source of re-introduction.

Chronic Pulmonary Interstitial Fibrosis in a Blue-Fronted Amazon Parrot (Amazona aestiva aestiva)

A 30-yr-old blue-fronted Amazon parrot (Amazon aestiva aestiva) was presented to the clinic with a history of sneezing more often during the last 2 mo. Physical examination revealed only a mild nasal discharge. Complete hematologic and plasma biochemical examination showed no abnormalities. Computerized tomography (CT) of the complete bird showed generalized lung alterations consistent with lung fibrosis. Two lung biopsies were taken. The results of the histologic examination of the biopsies confirmed the tentative CT diagnosis of pulmonary interstitial fibrosis. To our knowledge this is the first reported case of chronic pulmonary interstitial fibrosis diagnosed by means of a lung biopsy in an avian species. The histologic characteristics are discussed and compared with those of human idiopathic pulmonary fibrosis.

Renal cysts, nephrolithiasis, and ovarian cysts in a donkey suspected of having been sexually abused

A female donkey was thought by its owner to have been sexually abused because it had severe perineal swelling. Besides the perineal swelling and a very small vaginal erosion, there were no other abnormalities at clinical examination. Haematology and blood biochemistry revealed an increased leukocyte count, an elevated blood lactate concentration, and a low ionized calcium concentration. During night the donkey's condition deteriorated and it was euthanized in the morning. At necropsy severe haemorrhages were found within the subserosa of the caudal abdomen. Both kidneys were polycystic, and multiple calculi were found in the right kidney. Both ovaries had multiple cysts. Lesions (fibrosis and mineralization) were found in the liver, lungs, and mesenteric artery and were suggestive of an earlier parasitic infection. There was no evidence of sexual abuse.

Cowpoxvirus infection in the Patagonian cavy (Dolichotis patagonum) emerging disease in an educational animal park the first reported case

Generalized cowpox infection in the Patagonian cavy may represent a threat to the health of immunocompromised persons. We report the first case of cowpoxvirus infection in the Patagonian cavy in an educational animal park. The mara developed extensive pox lesions, shedding large amounts of viral particles. The ending of vaccination programmes against smallpox in the late 1970's may lead to an increase in susceptibility of humans to zoonotic poxviruses.

An outbreak of leptospirosis in seals (Phoca vitulina) in captivity

An outbreak of leptospirosis in seals (Phoca vitulina) in captivity is described. In a zoo in The Netherlands 5 adult seals died within 12 days. At necropsy all animals showed signs of acute septicaemia, consistent with acute leptospirosis. Serological examination of one animal was positive for antibodies against Leptospira interrogans serovar Icterohaemorrhagiae and the serologically closely related serovar Copenhageni. Polymerase chain reaction was positive in one other animal. 8 nutria (Myocastor coypus) were examined, serologically, through bacteriological culture and PCR. 81,8% (9/11) were serologically positive for Leptospira. The seals and nutria were housed in the same water system.

Atrioventricular conduction in mammalian species: Hemodynamic and electrical scaling

OBJECTIVES

The purpose of this study was to investigate scaling of the duration of late diastolic left ventricular (LV) filling in relation to AV conduction time (delay) (PR interval on the ECG) in mammals.

BACKGROUND

From mouse to whale, AV delay increases 10-fold, whereas body mass increases one million-fold. The apparent "mismatch" results from scaling of AV delay versus body and heart mass.

METHODS

We measured (1) mitral orifice diameter in 138 postmortem hearts of 48 mammalian species weighing between 17 g and 250 kg and (2) transmitral diastolic flow using magnetic resonance imaging (MRI) recordings of 10 healthy human individuals. (3) We visually inspected early and late diastolic LV filling. (4) We developed two physical models to explain scaling of late diastolic LV filling time.

RESULTS

(1) Diameter of the mitral orifice proportionally relates to heart length (third root of heart mass). (2) Atrial contraction starts at a fixed instant (+/- 80%) of the (normalized) cardiac cycle and contributes 31% +/- 5% to LV filling. (3) MRI shows that during diastole, the left atrium (LA) and LV form a single space. (4) The physical models relate the duration of late diastolic LV filling directly to heart length, the third root of heart mass.

CONCLUSIONS

(1) Late diastolic (LV) filling time scales with heart length (third root of heart mass). (2) No "mismatch" exists between AV delay and heart size. (3) Knowledge of the actual starting time of atrial contraction may contribute to better treatment of patients with heart failure. (4) The findings suggest that in evolution of mammalian species, hemodynamics commands electrical behavior of the heart.

Intraocular osteosarcoma in a dog

A 10-year-old German shepherd dog was presented with unilateral uveitis and hyphaema. Treatment was unsuccessful and the eye was enucleated. Intraocular osteosarcoma was diagnosed by histological examination.

Urinary glucocorticoid excretion in the diagnosis of hyperadrenocorticism in ferrets

Hyperadrenocorticism in ferrets is usually associated with unaltered plasma concentrations of cortisol and adrenocorticotropic hormone (ACTH), although the urinary corticoid/creatinine ratio (UCCR) is commonly elevated. In this study the urinary glucocorticoid excretion was investigated in healthy ferrets and in ferrets with hyperadrenocorticism under different circumstances. In healthy ferrets and in one ferret with hyperadrenocorticism, approximately 10% of plasma cortisol and its metabolites was excreted in the urine. High-performance liquid chromatography (HPLC) revealed one third of the urinary corticoids to be unconjugated cortisol; the other peaks mainly represented cortisol conjugates and metabolites. In 21 healthy sexually intact ferrets, the UCCR started to increase by the end of March and declined to initial values halfway the breeding season (June). In healthy neutered ferrets there was no significant seasonal influence on the UCCR. In two neutered ferrets with hyperadrenocorticism the UCCR was increased, primarily during the breeding season. In 27 of 31 privately owned ferrets with hyperadrenocorticism, the UCCR was higher than the upper limit of the reference range (2.1 x 10(-6)). In 12 of 14 healthy neutered ferrets dexamethasone administration decreased the UCCR by more than 50%, whereas in only 1 of the 28 hyperadrenocorticoid ferrets did the UCCR decrease by more than 50%. We conclude that the UCCR in ferrets primarily reflects cortisol excretion. In healthy sexually intact ferrets and in ferrets with hyperadrenocorticism the UCCR increases during the breeding season. The increased UCCR in hyperadrenocorticoid ferrets is resistant to suppression by dexamethasone, indicating ACTH-independent cortisol production.

Cartilage-free areas in the elbow joint of young golden retrievers

The present study describes cartilage-free areas on the ulnar trochlear notch and the humeral condyle of eight very young golden retrievers with otherwise healthy elbow joints. Remarkably, the youngest dog with full-thickness cartilage-free areas was only 8 weeks old. The younger dogs showed no macroscopic abnormalities on the locations that were affected in the older dogs. Two kinds of cartilage modifications were found. Cartilage-free areas at the edges of the articular cartilage layer were present on the humeral capitulum and on two locations of the ulna, (the medial and lateral at the base of the anconeal process, and the trochlear notch near the lateral coronoid process, which was fractured in two cases). Histological examination showed that these cartilage-free areas were filled with dense supportive tissue. Synovial cells covered this tissue as well as the surrounding hyaline cartilage. The synovial membrane covering the areas was macroscopically enlarged, but histological examination revealed no signs of inflammation. The second type of modification consisted of discoloration of the articular surface at the humeral trochlea. Histological examination revealed that in this area the articular surface was composed of fibrocartilage instead of hyaline cartilage. Apparently, there are locations within the elbow joint in which articular cartilage is not necessary for normal joint functioning. The presence of fibrocartilage on the articular surface of the humeral condyle is a surprising finding, for which no explanation has yet been found.

Hypercalcemia in two Amazon parrots with malignant lymphoma

Malignant lymphoma is a common malignancy in birds. Paraneoplastic syndromes, which are commonly observed in domestic animals, have not been reported in association with lymphoma in birds. Hypercalcemia and hyperglobulinemia were found on plasma chemistry in two Amazon parrots, which were presented with aspecific symptoms. In both cases radiography and ultrasound demonstrated signs of hepatomegaly, which proved to be due to malignant lymphoma on postmortem examination. The hypercalcemia was found to be most consistent with a paraneoplastic effect of the malignant lymphoma in these birds. The exact origin of the hyperglobulinemia remains unclear.