Morbidity and Mortality in Zoo-Housed Daurian Pikas (Ochotona dauurica).

Abstract

An investigation was conducted into the causes of morbidity and mortality in a breeding colony of Daurian pikas (Ochotona dauurica) housed at the Minnesota Zoo. Gross necropsy and histopathology records from all animals that died between 2011 and 2016 were reviewed to identify causes of death and associated comorbidities. Post-mortem tissue mineral panel data were also evaluated. A total of 69 necropsies were performed during the study period, with 30 cases having complete histopathology available for analysis. No animals survived to the geriatric age class. The most common cause of mortality was systemic abscessation (n = 11) secondary to a Gram-negative, non-fermenting, rod-shaped bacterium identified as Castellaniella sp. Other confirmed causes of death included traumatic hemorrhage (n = 4), hepatic necrosis (n = 2), hemorrhagic enteritis (n = 1), and myocardial necrosis (n = 1). Hemothorax occurred in two animals within 24 h of venipuncture. Frequently observed comorbidities included cachexia of undetermined origin (n = 18), cutaneous ascariasis (n = 8), oxyuriasis (n = 8), coccidiosis (n = 5), dental malocclusion (n = 4), hepatic hemosiderosis (n = 3), and small intestinal non-hemolytic Escherichia coli infection (n = 3). Elevated tissue iron concentrations were also detected in several individuals, suggesting potential species sensitivity to iron overload. This review provides important baseline data on morbidity and mortality in managed Daurian pika populations and highlights the need for further research into their husbandry, nutrition, and medical management to improve welfare and survival under human care.