A longitudinal observational study in two cats naturally-infected with hepadnavirus.

Hepatitis B virus (HBV) is a major cause of liver disease in humans including chronic hepatitis and hepatocellular carcinoma. Domestic cat hepadnavirus (DCH), a novel HBV-like hepadnavirus, was identified in domestic cats in 2018. From 6.5 %-10.8 % of pet cats are viremic for DCH and altered serological markers suggestive of liver damage have been identified in 50 % of DCH-infected cats. DCH DNA has been detected in association with characteristic lesions of chronic hepatitis and with hepatocellular carcinoma in cats, suggesting a possible association. In this study longitudinal molecular screening of cats infected with DCH was performed to determine if DCH can cause chronic infections in cats. Upon re-testing of sera from five DCH-positive animals, 2-10 months after the initial diagnosis, three cats tested negative for DCH on two consecutive occasions using quantitative PCR. Two other cats remained DCH-positive, including an 8-month-old female cat re-tested four months after the initial positive result, and a 9-year-old male cat, which tested positive for DCH on six occasions over an 11-month period. The latter had a history of chronic hepatopathy with jaundice, lethargy and elevated serum alanine transaminase levels (ALT). During the period of observation, DCH titers ranged between 1.64 × 105 and 2.09 × 106 DNA copies/mL and ALT was persistently elevated, suggesting chronic infection. DCH DNA was not detected in oral, conjunctival, preputial and rectal swabs from the two animals collected at several time points. Long-term (chronic) infection would be consistent with the relatively high number of viremic cats identified in epidemiological investigations, with the possible association of DCH with chronic hepatic pathologies and with what described with HBV in human patients.

Diagnosis and treatment considerations in a case of malignant mesenchymoma in an African fur seal (Arctocephalus pusillus).

A 20-yr-old African fur seal (Arctocephalus pusillus) presented with a slowly growing mass located on the dorsum at the level of the last thoracic vertebrae. The mass was hard, 10 cm in diameter, and not adherent to the underlying tissues. Multiple biopsies were collected for histopathology and revealed extensive areas of necrosis, small nodules of malignant mesenchymal proliferation with areas of chondroid metaplasia, and atypical cells in vessel walls. The morphologic diagnosis was suggestive of malignant mesenchymal neoplasia originating from the vascular wall. The mass was removed 1 mo later due to ulceration and infection. Histologically, based on the World Health Organization's classification of neoplastic processes in domestic animals, the tumor was consistent with malignant mesenchymoma. The margins of resection revealed the presence of neoplastic cells. Based on these results, the particular species involved, the high local invasiveness, and the high metastatic index of this malignant tumor in domestic mammals and humans, the prognosis was poor. The animal died 6 mo later with metatastic disease.