Canine distemper virus infection of vaccinal origin in a 14-week-old puppy.

The body of a 14-wk-old puppy (Canis familiaris) was submitted to the Animal Health Laboratory, University of Guelph, Ontario for postmortem examination following a history of intermittent anorexia and lethargy progressing to pyrexia, pruritic skin rash, mucoid nasal discharge, decreased mentation, dysphagia, muscle twitches, and focal seizures. Gross examination revealed rhinitis and pulmonary edema. Histologically, there was fibrinonecrotizing bronchopneumonia, tracheitis, and neutrophilic and lymphohistiocytic rhinitis; rarely within the cortical gray and white matter of the brain were small clusters of glial cells, with rare individual neutrophils in the choroid plexus. Although canine distemper was suspected, none of the usual supportive histologic lesions of distinct syncytial cells, viral inclusion bodies, or demyelinating leukoencephalitis were observed. Lung and brain tissues were PCR-positive for canine distemper virus (CDV), and CDV was detected immunohistochemically in the brain. The agent from the PCR-positive sample from the brain was genotyped and was a 99.9% match to the CDV Rockborn strain, indicating that the disease agent in our case was vaccinal in origin. Our unusual case highlights the possibility of reversion to virulence in a modified-live virus vaccine, and the occurrence of a disease in the absence of a full complement of the usual and compatible histologic lesions.

Orofacial masses in domestic rabbits: a retrospective review of 120 cases from 2 institutions, 2000-2023.

Orofacial masses or swellings are a common presenting complaint in lagomorphs. Similar gross appearances of the masses can complicate clinical interpretation, and histologic review often provides the final diagnosis. Underlying causes vary from infectious to neoplastic. Although inflammatory changes are most commonly reported, various neoplasms occur, although the prevalence of specific tumor types is relatively unknown. We reviewed retrospectively 120 cases (87.5% biopsy, 12.5% autopsy) of neoplastic and non-neoplastic orofacial masses received from January 2000-February 2023 at 2 institutions: University of Guelph, Canada (Animal Health Laboratory and Department of Pathobiology), and Finn Pathologists, United Kingdom. All final diagnoses were achieved through histologic assessment. We included masses or mass-like swellings from the oral cavity, including the mandible and maxilla, and surrounding skin and soft tissues of the oral cavity and jaw. Submissions included pet and commercial (meat and fur) rabbits. Neoplastic lesions were most common (60%), including trichoblastomas, papillomas, melanocytic neoplasms, sarcomas, round-cell tumors, carcinomas (including squamous cell carcinoma), lipomas, odontogenic neoplasms, polyps, osteoma, neuroma, peripheral keratinizing ameloblastoma, and apocrine adenoma. Inflammatory diagnoses (30%) included abscesses, osteomyelitis, dermatitis, and sialadenitis. Other diagnoses (7%) included cysts, as well as hyperplastic skin and proliferative bone lesions. Three cases had no definitive diagnosis. The importance of histologic assessment in diagnosing orofacial "masses" in rabbits is highlighted, given that the most common diagnostic category overall was neoplasia.

Unilateral primary carcinoma of the kidney with central nervous system invasion and vertebral lysis in a cat.

Case summary: A young adult female spayed domestic shorthair cat presented for acute hindlimb weakness and anorexia with a 1-month history of lethargy, hyporexia and weight loss. A mass was palpable in the caudolateral abdomen and the left hindlimb was diffusely edematous. Abdominal ultrasound showed hydronephrosis of the left kidney with suspected hydroureter and heterogeneous tissue in the dorsal abdomen. CT evaluation confirmed a mass extending from the left kidney through the lumbar musculature with hydronephrosis, aortic attenuation, caudal vena caval thrombosis and lysis of vertebrae 4 and 5. Fine-needle aspiration of the mass suggested squamous cell carcinoma. Owing to clinical deterioration, euthanasia was elected. At necropsy, the left kidney was firmly adhered to the lumbar region with tissue that obliterated the musculature and surrounded the aorta and vena cava. There was hydronephrosis of the left kidney. Histopathologic evaluation of the mass revealed islands of neoplastic epithelial cells separated by fibrous connective tissue and areas of gradual keratinization with rare squamous metaplasia. The histologic diagnosis was invasive carcinoma with desmoplasia and vascular invasion. Relevance and novel information: Primary carcinomas of the kidney in cats are rare and this report documents a progression of disease not previously reported in cats. This is the second reported case of a primary carcinoma of renal origin with features of squamous cell carcinoma in a cat, and the first with lumbar and vascular invasion. This is also the first use of kidney injury molecule-1 to help investigate tumor differentiation in cats.

Use of immune repertoire sequencing to resolve discordant microscopic and immunochemical findings in a case of T cell-rich large B cell lymphoma in a young dog.

BACKGROUND: Lymphocytic neoplasms with frequent reactive lymphocytes are uncommonly reported in dogs, and can pose a diagnostic challenge. Different diagnostic modalities such as cytology, flow cytometry, histopathology, immunohistochemistry, and clonality testing, are sometimes required for a diagnosis. This report illustrates the value of using a multi-modal diagnostic approach to decipher a complex lymphocytic tumor, and introduces immune repertoire sequencing as a diagnostic adjunct. CASE PRESENTATION: A 10-month-old Great Dane was referred for marked ascites. Cytologic analysis of abdominal fluid and hepatic aspirates revealed a mixed lymphocyte population including numerous large lymphocytes, yielding a diagnosis of lymphoma. Flow cytometrically, abdominal fluid lymphocytes were highly positive for CD4, CD5, CD18, CD45, and MHC II, consistent with T cell lymphoma. Due to a rapidly deteriorating clinical condition, the dog was euthanized. Post mortem histologic evaluation showed effacement of the liver by aggregates of B cells surrounded by T cells, suggestive of hepatic T cell-rich large B cell lymphoma. Immune repertoire sequencing confirmed the presence of clonal B cells in the liver but not the abdominal fluid, whereas reactive T cells with shared, polyclonal immune repertoires were found in both locations. CONCLUSIONS: T cell-rich large B cell lymphoma is a rare neoplasm in dogs that may be challenging to diagnose and classify due to mixed lymphocyte populations. In this case, the results of histopathology, immunohistochemistry and immune repertoire sequencing were most consistent with a hepatic B cell neoplasm and reactive T cells exfoliating into the abdominal fluid. Immune repertoire sequencing was helpful in delineating neoplastic from reactive lymphocytes and characterizing repertoire overlap in both compartments. The potential pitfalls of equating atypical cytomorphology and monotypic marker expression in neoplasia are highlighted.

Massive uterine lipoleiomyoma and leiomyoma in a miniature poodle bitch.

A 15-year-old, intact, female miniature poodle was presented for further evaluation of a large abdominal mass. Computed tomography was conducted to determine the origin of the mass and 2 large uterine masses were discovered. Ovariohysterectomy was performed and histopathological evaluation revealed a massive uterine lipoleiomyoma (27 × 17 × 15 cm), the largest recorded in the veterinary literature, and a smaller leiomyoma (7 × 5 × 4 cm).

Lipoléiomyome utérin massif et léiomyome chez une chienne Caniche miniature. Une chienne Caniche miniature intacte âgée de 15 ans a été présentée pour une évaluation approfondie d'une grosse masse abdominale. Une analyse par tomodensitométrie a été réalisée afin de déterminer l'origine de la masse et deux grandes masses utérines ont été découvertes. L'ovariohystérectomie a été réalisée et l'évaluation histopathologique a révélé un lipoléimomyome utérin massif (27 × 17 × 15 cm), le plus gros jamais consigné dans la littérature vétérinaire et un plus petit léiomyome (7 × 5 × 4 cm).(Traduit par Isabelle Vallières).

Introducing forensic entomology in cases of suspected animal neglect.

Cases of arthropod-infested, abandoned or abused animals are sometimes brought to the attention of veterinarians by animal welfare authorities, with the requirement for a full postmortem examination towards criminal or civil proceedings. In these situations, entomology is an important support tool for the pathologists' investigation since the presence of arthropod life cycle stages serve as reliable forensic markers, especially for blowflies which form the first waves of activity following death. In the present study, 70 cadavers from a total of 544 referred to the Institute of Veterinary Science, University of Liverpool, between 2009 and 2014 displayed evidence of infestation. Here, the authors introduce principles of applied entomology and simplified approaches for estimating the minimum time since death, relevant in the context of routine submissions and the broad remit of individual cases. Despite often limited availability of scene of the crime and local thermal data, the interpretation of the minimum postmortem interval has nonetheless proved valuable as an adjunct to the expert pathology report. However, future developments and enhanced accuracy in this area of animal welfare require resource and training in expertise, and agreed standardisation of both laboratory and field procedures.