Medical records from 68 slender tailed cloud rats, Phloeomys pallidus, housed at the Bronx Zoo between July 1985 and September 2006 were reviewed. Thirty-one animals (45.6%) survived to adulthood (>2 years) and remained at the Bronx Zoo. Seven of these animals (22.5%) were diagnosed with cryptococcal pneumonia.
Affected animals ranged in age from 5.5–13 years at time of presentation. Three cases presented clinically; fungal serology was positive in all three. Clinical signs and physical examination findings included dyspnea, thin body condition/muscle wasting, harsh lung sounds, and lethargy. Diffuse interstitial pneumonia was demonstrated radiographically. Clinical pathology abnormalities included leukocytosis (mature neutrophilia), hyperkalemia, and azotemia. One geriatric animal had concurrent pulmonary neoplasia and was euthanatized. Treatment in the other two consisted of oxygen therapy, antibiotics, and one or more antifungals (Flucytosine/Ancoban, Valeant Pharmaceuticals, Costa Mesa, CA USA 92626, 75 mg/kg PO BID; Fluconazole, Greenstone, Peapack, NJ USA 07977, 12 mg/kg PO BID; Amphotericin B, X-Gen Pharmaceuticals, Northport, NY, USA 11768, 0.25–0.5 mg/kg/day iIO and 1–5 mg nebulized BID); however, neither case survived. Diagnosis in the majority of cases was made after death (n=4). Gross necropsy findings included granulomatous pneumonia and thoracic lymphadenomegaly. Histologic lesions consistent with cryptococcosis were noted in the lungs of all cases. Additionally, infection of lymph nodes, gastrointestinal tract, liver or pancreas was seen in some cases.
C. neoformans is an opportunistic saprophyte with worldwide distribution in which immunocompromise often predisposes to infection.1,3,4 It most commonly colonizes the respiratory tract but has also been shown to affect the gastrointestinal tract and can invade directly via skin wounds.2 Based on the large numbers of cases seen in this species at the Bronx Zoo, compared to very infrequent cases in all other species necropsied, cloud rats appear to be unusually susceptible to this pathogen.
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