Aquaculture related humpback whale entanglements in coastal waters of British Columbia from 2008-2021.

Over the past two decades, increasing numbers of humpback whales have been returning to feed in the inshore waters of British Columbia (BC) where marine aquaculture farms are situated. This has led to growing concerns that the presence of aquaculture farms may pose an entanglement threat to humpback whales. However, it is not known whether aquaculture facilities attract humpback whales, or whether there are factors that increase the likelihood of humpback whale, becoming entangled and dying. We examined eight reports of humpback whales interacting with Atlantic salmon farms in BC from 2008 to 2021 to evaluate the conditions that may have contributed to their entanglements. Of the eight entangled humpbacks, three individuals died and five were successfully disentangled and released. All were young animals (1 calf, 7 subadults). Multiple factors were associated with two or more of the reported incidents. These included facility design, environmental features, seasonality, humpback whale age, and feeding behaviour. We found that humpback whales were most commonly entrapped in the predator nets of the aquaculture facilities (6/8 incidents), and were less often entangled in anchor support lines (2/8). The presence of salmon smolts did not appear to be an attractant for humpback whales given that half of the reported entanglements (4/8) occurred at fallowed salmon farms. Almost all of the entanglements (7/8) occurred in late winter (prior to the seasonal return of humpbacks) and during late fall (after most humpbacks have migrated south). Overall, the number of humpback whales impacted by fish farms was small compared to the numbers that return to BC (> 7,000) and accounted for <6% of all types of reported entanglements in BC. Human intervention was required to release humpback whales at fish farms, which points to the need to have well-established protocols to minimize entanglements and maximize successful releases.

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.

Paranannizziopsis spp. infections in wild snakes and a qPCR assay for detection of the fungus.

The emergence of ophidiomycosis (or snake fungal disease) in snakes has prompted increased awareness of the potential effects of fungal infections on wild reptile populations. Yet, aside from Ophidiomyces ophidiicola, little is known about other mycoses affecting wild reptiles. The closely related genus Paranannizziopsis has been associated with dermatomycosis in snakes and tuataras in captive collections, and P. australasiensis was recently identified as the cause of skin infections in non-native wild panther chameleons (Furcifer pardalis) in Florida, USA. Here we describe five cases of Paranannizziopsis spp. associated with skin lesions in wild snakes in North America and one additional case from a captive snake from Connecticut, USA. In addition to demonstrating that wild Nearctic snakes can serve as a host for these fungi, we also provide evidence that the genus Paranannizziopsis is widespread in wild snakes, with cases being identified in Louisiana (USA), Minnesota (USA), Virginia (USA), and British Columbia (Canada). Phylogenetic analyses conducted on multiple loci of the fungal strains we isolated identified P. australasiensis in Louisiana and Virginia; the remaining strains from Minnesota and British Columbia did not cluster with any of the described species of Paranannizziopsis, although the strains from British Columbia appear to represent a single lineage. Finally, we designed a pan-Paranannizziopsis real-time PCR assay targeting the internal transcribed spacer region 2. This assay successfully detected DNA of all described species of Paranannizziopsis and the two potentially novel taxa isolated in this study and did not cross-react with closely related fungi or other fungi commonly found on the skin of snakes. The assay was 100% sensitive and specific when screening clinical (skin tissue or skin swab) samples, although full determination of the assay's performance will require additional follow up due to the small number of clinical samples (n = 14 from 11 snakes) available for testing in our study. Nonetheless, the PCR assay can provide an important tool in further investigating the prevalence, distribution, and host range of Paranannizziopsis spp. and facilitate more rapid diagnosis of Paranannizziopsis spp. infections that are otherwise difficult to differentiate from other dermatomycoses.

Acute microcystin exposure induces reversible histopathological changes in Chinook Salmon (Oncorhynchus tshawytscha) and Atlantic Salmon (Salmo salar).

Atlantic Salmon (Salmo salar) and Chinook Salmon (Oncorhynchus tshawytscha) develop a severe liver disease called net-pen liver disease (NPLD), which is characterized by hepatic lesions that include megalocytosis and loss of gross liver structure. Based on studies where salmonids have been exposed to microcystin (MC) via intraperitoneal injection, NPLD is believed to be caused by MC exposure, a hepatotoxin produced by cyanobacteria. Despite the link between MC and NPLD, it remains uncertain if environmentally relevant MC exposure is responsible for NPLD. To determine if we could produce histopathology consistent with NPLD, we compared the response of Atlantic and Chinook Salmon sub-lethal MC exposure. Salmon were orally gavaged with saline or MC containing algal paste and sampled over 2 weeks post-exposure. Liver lesions appeared by 6 h but were resolved 2-weeks post-exposure; histopathological changes observed in other tissues were not as widespread, nor was their severity as great as those in the liver. There was no evidence for NPLD due to the absence of hepatic megalocytosis. These results indicate that the development of NPLD is not due to acute MC exposure but may be associated with higher MC concentration occurring in food, long-term exposure through drinking of contaminated seawater and/or interactions with other marine toxins.

Incursions of rabbit haemorrhagic disease virus 2 in Canada-Clinical, molecular and epidemiological investigation.

Rabbit haemorrhagic disease virus 2 (RHDV2) is a newly emerging Lagovirus belonging to the family Caliciviridae. After its first discovery in 2010 in France, this highly pathogenic virus rapidly spread to neighbouring countries and has become the dominant strain, replacing the classical RHDV strains. RHDV2 was first reported in North America in 2016 in Mont-Joli, Quebec, Canada, and it was reported again in 2018 and 2019 on Vancouver Island and the southwest mainland of British Columbia (BC). The whole genome sequence of the RHDV2 Quebec isolate resembled the 2011 RHDV2-N11 isolate from Navarra, Spain with 97% identity at the nucleotide level. The epidemiological investigation related to this outbreak involved three hobby farms and one personal residence in Quebec. In February 2018, high mortality was reported in a large colony of feral rabbits on the Vancouver Island University Campus, Nanaimo, BC. The virus identified showed only 93% identity to the Quebec RHDV2 isolate at the nucleotide level. Additional cases of RHDV2 on Vancouver Island and on the BC mainland affecting feral and captive domestic, and commercial rabbits were reported subsequently. Vaccination was recommended to control the outbreak and an inactivated bivalent vaccine was made available to the private veterinary practices. In June 2019, an isolated RHDV2 outbreak was reported in pet rabbits in an apartment building in Vancouver, BC. This virus showed only 97% identity to the RHDV2 isolates responsible for the BC outbreak in 2018 at the nucleotide level, suggesting that it was an independent incursion. The outbreak in BC killed a large number of feral European rabbits; however, there were no confirmed cases of RHD in native rabbit species in BC.

Author Correction: Piscine orthoreovirus demonstrates high infectivity but low virulence in Atlantic salmon of Pacific Canada.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Rare neural crest tumor in teleost species: olfactory neuroblastoma in a spotted pike-characin Boulengerella maculata.

One spotted pike-characin Boulengerella maculata, managed in a public display aquarium for 7 yr, developed a small unilateral pink growth associated with the right nare. The growth eventually extended through both nares after 5 mo. B. maculata is a species of piscivorous fish that relies on visual acuity when hunting prey. The rapidly-growing bilateral tumor would have impeded vision if left untreated. The fish was managed for over 10 mo using only surgical debulking, topical liquid nitrogen, and occasional nonsteroidal anti-inflammatory medications as needed to reduce tumor size and restore sight. Diagnosis proved challenging due to superimposed inflammation, neoplasm cellular inconsistencies, and a lack of proven immunohistochemical stains or other diagnostic stains. Using tumor location and appearance, histopathology, advanced imaging, electron microscopy, special staining, and immunohistochemistry, the ultimate diagnosis confirmed olfactory neuroblastoma, or esthesioneuroblastoma. Although long-term prognosis is poor, hunting strategy of the affected species may dictate quality of life, as appetite, body condition, and behavior remained largely unchanged in this animal until time of euthanasia.

First report of ranavirus mortality in a common snapping turtle Chelydra serpentina.

An adult male snapping turtle with marked palpebral edema and multifocal skin ulceration was found alive in a marsh in southern Ontario in summer 2017. The turtle was transported to a rehabilitation facility and died 4 d after arrival. The carcass was submitted to the Canadian Wildlife Health Cooperative for post-mortem examination. Gross lesions included ulcerative conjunctivitis, necrotizing stomatitis, and splenomegaly. Microscopically, this corresponded to multisystemic fibrinonecrotizing vasculitis and severe fibrinous splenic necrosis. Liver tissue tested positive for frog virus 3-like ranavirus and negative for herpesvirus via polymerase chain reaction. The gross and microscopic lesions were consistent with previous reports of ranavirus infection in turtles and were severe enough to have been the cause of death in this case. This is the first report of morbidity and mortality in a common snapping turtle with a ranavirus infection, and the first reported case of ranavirus infection in a reptile in Canada. Ranaviruses are considered to be an emerging infectious disease in chelonians as they are increasing in distribution, prevalence, and host range.

URINARY BLADDER TRANSITIONAL CELL CARCINOMA AND CARCINOMATOSIS IN A LINNAEUS'S TWO-TOED SLOTH, CHOLOEPUS DIDACTYLUS.

A 19-yr-old female Linnaeus's two-toed sloth (Choloepus didactylus) with a history of urinary incontinence, ascites, and behavioral changes was euthanized after diagnostic imaging revealed a large bladder mass. On gross necropsy, the sloth had a severely thickened bladder mucosa, partial urinary obstruction, and nonseptic exudate in the peritoneal cavity. Histopathology showed a malignant and highly invasive transitional cell (urothelial) carcinoma with transmural and intra-abdominal invasion and diffuse carcinomatosis. Immunohistochemistry for expression of pancytokeratin (AE1/AE3), cytokeratin 7 (CK7), cytokeratin 20 (CK20), and uroplakin III was performed to confirm the diagnosis of transitional cell carcinoma. Neoplastic cells had a strong cytoplasmic immunoreactivity with the antipancytokeratin antibody clone AE1/AE3, which was consistent with a neoplasm of epithelial origin. Neoplastic cells were negative for expression of CK20. This is the first detailed report describing the antemortem diagnosis of urinary bladder transitional cell carcinoma with carcinomatosis in a two-toed sloth.

Piscine orthoreovirus demonstrates high infectivity but low virulence in Atlantic salmon of Pacific Canada.

Piscine orthoreovirus (PRV) is ubiquitous in farmed Atlantic salmon and sometimes associated with disease - most notably, Heart and Skeletal Muscle Inflammation (HSMI). However, PRV is also widespread in non-diseased fish, particularly in Pacific Canada, where few cases of severe heart inflammation have been documented. To better understand the mechanisms behind PRV-associated disease, this study investigated the infection dynamics of PRV from Pacific Canada and the potential for experimental passage of putatively associated heart inflammation in Pacific-adapted Mowi-McConnell Atlantic salmon. Regardless of the PRV source (fish with or without HSMI-like heart inflammation), infections led to high-load viremia that induced only minor focal heart inflammation without significant transcriptional induction of inflammatory cytokines. Repeated screening of PRV dsRNA/ssRNA along with histopathology and gene expression analysis of host blood and heart tissues identified three distinct phases of infection: (1) early systemic dissemination and replication without host recognition; (2) peak replication, erythrocyte inclusion body formation and load-dependent host recognition; (3) long-term, high-load viral persistence with limited replication or host recognition sometimes accompanied by minor heart inflammation. These findings contrast previous challenge trials with PRV from Norway that induced severe heart inflammation and indicate that strain and/or host specific factors are necessary to initiate PRV-associated disease.

Piscine Orthoreovirus from Western North America Is Transmissible to Atlantic Salmon and Sockeye Salmon but Fails to Cause Heart and Skeletal Muscle Inflammation.

Heart and skeletal muscle inflammation (HSMI) is a significant and often fatal disease of cultured Atlantic salmon in Norway. The consistent presence of Piscine orthoreovirus (PRV) in HSMI diseased fish along with the correlation of viral load and antigen with development of lesions has supported the supposition that PRV is the etiologic agent of this condition; yet the absence of an in vitro culture system to demonstrate disease causation and the widespread prevalence of this virus in the absence of disease continues to obfuscate the etiological role of PRV with regard to HSMI. In this study, we explore the infectivity and disease causing potential of PRV from western North America-a region now considered endemic for PRV but without manifestation of HSMI-in challenge experiments modeled upon previous reports associating PRV with HSMI. We identified that western North American PRV is highly infective by intraperitoneal injection in Atlantic salmon as well as through cohabitation of both Atlantic and Sockeye salmon. High prevalence of viral RNA in peripheral blood of infected fish persisted for as long as 59 weeks post-challenge. Nevertheless, no microscopic lesions, disease, or mortality could be attributed to the presence of PRV, and only a minor transcriptional induction of the antiviral Mx gene occurred in blood and kidney samples during log-linear replication of viral RNA. Comparative analysis of the S1 segment of PRV identified high similarity between this North American sequence and previous sequences associated with HSMI, suggesting that factors such as viral co-infection, alternate PRV strains, host condition, or specific environmental circumstances may be required to cause this disease.

Metastatic anaplastic adenocarcinoma suspected to be of mammary origin in an intact male rabbit (Oryctolagus cuniculus).

A 7-year-old, intact male, pet dwarf rabbit (Oryctolagus cuniculus) was presented for a ventral abdominal subcutaneous mass. Histolopathology of the resected mass was suggestive of a mammary adenocarcinoma. Six months later, the rabbit died from severe dyspnea. Necropsy showed recurrence of the original mass with hepatic and pulmonary metastasis of the anaplastic adenocarcinoma, suspected to be of mammary origin.

Adénocarcinome anaplasique métastatique, suspecté d'origine mammaire, chez un lapin mâle intact(Oryctolagus cuniculus) . Un lapin nain de compagnie mâle intact âgé de 7 ans (Oryctolagus cuniculus) a été présenté pour une masse sous-cutanée abdominale ventrale. L'histopathologie de la masse reséquée était en faveur d'un adénocarcinome mammaire. Six mois plus tard, le lapin est mort de dyspnée grave. La nécropsie a montré la récurrence de la masse originale avec des métastases hépatiques et pulmonaires de l'adénocarcinome anaplasique, suspecté d'origine mammaire.(Traduit par Isabelle Vallières).

Severe gastric impaction secondary to a gastric polyp in a horse.

A 13-year-old Percheron gelding was presented for refractory gastric impaction. At necropsy a pedunculated 10 cm × 11 cm × 14 cm mass, histologically identified as an inflammatory polyp, was suspected to have been partly obstructing the pylorus. This is the first report of a polyp resulting in gastric outflow obstruction in a horse.

Surcharge gastrique grave secondaire à un polype gastrique chez un cheval. Un hongre Percheron âgé de 13 ans a été présenté pour une surcharge gastrique réfractaire. À la nécropsie, une masse pédonculée de 10 cm × 11 cm × 14 cm, identifiée à l'histologie comme un polype inflammatoire, a été soupçonnée d'avoir partiellement bloqué le pylore. Il s'agit du premier rapport d'un polype qui se traduit par l'obstruction de l'écoulement gastrique chez un cheval.(Traduit par Isabelle Vallières).

Cerebellar granuloprival degeneration in an Australian kelpie and a Labrador retriever dog.

A 7-month-old Australian kelpie dog and a 14-month-old Labrador retriever dog were diagnosed with an uncommon form of cerebellar abiotrophy called cerebellar granuloprival degeneration. This was characterized by a loss of the granular neurons with relative sparing of the Purkinje neurons.

Dégénérescence cérébelleuse granuloprive chez un chien Kelpie australien et un chien Labrador retriever. Un chien Kelpie australien âgé de 7 mois et un chien Labrador retriever âgé de 14 mois ont été diagnostiqués avec une forme rare d'abiotrophie cérébelleuse appelée dégénérescence cérébelleuse granuloprive. Elle a été caractérisée par la perte de neurones granulaires en épargnant en grande partie les neurones de Purkinje.(Traduit par Isabelle Vallières).