Spontaneous neoplasms in captive Virginia opossums ( Didelphis virginiana): a retrospective case series (1989-2014) and review of the literature.

This retrospective project summarizes the types of neoplasms identified in Virginia opossums ( Didelphis virginiana) presented to the University of Tennessee, College of Veterinary Medicine (UTCVM) postmortem service in 1989-2014 and serves as a review of the literature. Of the 85 Virginia opossums identified from the UTCVM case database, there were 17 diagnoses of neoplasia from 12 cases (14%). These cases included 8 females, 2 males, and 2 neutered males. All opossums with known ages (11 of 12) were >2 y old. Pulmonary tumors, specifically minimally invasive or lepidic-predominant adenocarcinomas, were the most common diagnosis and accounted for 53% (9 of 17) of the neoplasms. Additional tumors included acute myeloid leukemia with eosinophil maturation, hepatic hemangiosarcoma, sarcoma (unknown origin), squamous cell carcinoma, disseminated mast cell tumor, trichoblastoma, thyroid adenoma, and an osteoma. These findings serve as a reference for the types of spontaneous neoplasms in Virginia opossums; based on these findings, neoplasia should be considered as a differential in mature captive Virginia opossums.

Spontaneous proliferative and neoplastic lesions in thyroid and parathyroid glands of nondomestic felids.

Based on microscopic and immunohistochemical characterization, we documented spontaneous proliferative and neoplastic lesions in the thyroid and parathyroid glands of nondomestic felids. Ten animals (4 leopards, 3 tigers, and 3 cougars), all with a previous diagnosis of thyroid neoplasia were identified from the University of Tennessee College of Veterinary Medicine database. The mean age of affected animals was 15.9 y. Twelve neoplasms were identified; 2 animals had 2 concurrent neoplasms. After immunohistochemical characterization using a panel of chromogranin A, thyroglobulin, and calcitonin, 7 of the former thyroid neoplasms were diagnosed as thyroid adenomas, 1 was diagnosed as a thyroid carcinoma, and 4 were diagnosed as parathyroid adenomas. No thyroid medullary neoplasms (C-cell tumors) were diagnosed in the current study. Most of the diagnosed neoplasms were benign (11 of 12), and metastasis was not documented in the single carcinoma. Only 2 animals were suspected to have functional neoplasms (1 thyroid adenoma and 1 parathyroid adenoma), based on associated tissue lesions or serum biochemistry. Other documented lesions in the thyroid and parathyroid glands included thyroid nodular hyperplasia ( n = 7), parathyroid hyperplasia associated with chronic renal disease ( n = 2), a thyroid abscess, and a branchial cyst. Parathyroid adenomas were more commonly diagnosed than expected in comparison with domestic cats. We demonstrated that an immunohistochemistry panel for thyroglobulin, calcitonin, and chromogranin A can be used to differentiate neoplasms of thyroid from parathyroid origin in nondomestic felids.

Characterization of a novel Canine distemper virus causing disease in wildlife.

Canine distemper virus (CDV) is a common cause of a multisystemic disease in both domestic dogs and wildlife species, including raccoons and foxes. Outbreaks of CDV in domestic dogs in eastern Tennessee have occurred since 2012, and it was determined that these outbreaks resulted from a novel genotype of CDV. We hypothesized that this virus is also infecting area wildlife and may be a source of the virus for these outbreaks in dogs. From 2013 to 2014, autopsies were performed and tissues collected from raccoons (Procyon lotor; n = 50) and gray foxes (Urocyon cinereoargenteus; n = 8) for CDV testing. A real-time reverse transcription PCR was used to document the presence of CDV in tissue samples, and a portion of the virus was subsequently sequenced for phylogenetic analysis. A high percentage of wildlife, both with (86%) and without (55%) clinical signs, tested positive for CDV, with the majority (77%) testing positive for the novel genotype. Microscopic findings, including syncytia in the lungs and viral inclusion bodies in urothelium, astrocytes, neurons, and bronchiolar epithelium, were also consistent with canine distemper. Minimal inflammation in the central nervous system of affected animals was indicative of the acute neurologic form of the disease. Pneumonia and parasitism were also commonly found in CDV-infected animals. Based on these results, CDV appears to be prevalent in eastern Tennessee wildlife. Subclinical or clinically recovered shedders are a potential source of this novel genotype for domestic dogs, and this genotype is genetically distinct from vaccine strains.