Two cases of canine adenovirus (CAV)-1 occurred 5 yr apart in two Malayan sunbears (Helarctos malayanus). Though the two individuals did not overlap in lifetime, each had contact with an asymptomatic conspecfic that shared the same exhibit. In the first case, a 23 yr old female presented acutely comatose. MRI revealed hypoperfusion of the head and brain; euthanasia was elected. Virus neutralization (VN) serology was negative for CAV-1 and CAV-2. Histopathology revealed disseminated endotheliotropic adenovirus infection. Amplified viral DNA from brain samples had 100% identity to CAV-1.
Five years later, a 3-yr-old female had one day of lethargy and anorexia with progression in 24 hr to a coma with vertical nystagmus. Sedation was maintained by diazepam CRI (0.25–0.5 mg/kg/hr i.v. in 0.9% saline) for 36 hr while supportive care was provided. Ganciclovir (250 mg i.v. b.i.d. for 2 days) and cidofovir (375 mg i.v. once) were administered. Complicating disseminated intravascular coagulopathy was managed with heparin (5 USP units/kg s.q. t.i.d. for 2 days). Recovery allowed release from the hospital 12 days after presentation. A significant rise in CAV antibody titer via VN, as well as, a positive PCR in whole blood were demonstrated on acute and convalescent samples (days 1 and 12).
Skunks and raccoons observed within/near the exhibit were suspected as the source of exposure. Improved wildlife exclusion methods were implemented; all conspecific sunbears were vaccinated intramuscularly twice 1 mo apart with a modified live multivalent vaccine containing CAV-2.
The authors thank the IAMS Pet Imaging Center, Redwood City, CA for advanced imaging, Drs. Linda Lowenstine, Megan Jones, and Mark Schrenzell for histopathology and virus identification, and the Animal Care Staff and Veterinary Technicians at the Oakland Zoo for their dedication to both bears.
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