SARS-CoV-2 morbidity, treatment interventions, and vaccination practices in tigers (Panthera tigris ssp) in North American zoos

Abstract

OBJECTIVE Evaluate SARS-CoV-2 morbidity, mortality, clinical signs, treatment interventions, and vaccination practices in tigers under professional care. ANIMALS Amur (Panthera tigris altaica), Sumatran (Panthera tigris sumatrae), and Malayan (Panthera tigris jacksoni) tigers managed under the Tiger Species Survival Plan (SSP). METHODS A retrospective, voluntary online survey was sent to all North American zoos holding SSP tigers between January 2020 and June 2023. RESULTS Responses were received from 55 of 108 institutions (51%) housing 162 tigers in total, and SARS-CoV-2 infection was diagnosed in 39 tigers from 15 institutions (20 Amur, 8 Sumatran, and 11 Malayan [1 to 18 years old; 17 males and 22 females]). This corresponds to a minimum study group infection incidence of 24% over 42 months. Clinical signs included dry cough (82%), inappetence (64%), lethargy (62%), nasal discharge (46%), wheezing (31%), wet cough (18%), and ocular discharge (15%). Most cases were characterized as mild (n = 22) or moderate (14). A single case was characterized as severe. Two cases were asymptomatic. Seventeen positive tigers had been vaccinated once (n = 8) or twice (9) for SARS-CoV-2 prior to infection. No deaths due to SARS-CoV-2 were reported in the study group. Treatment interventions included antibiotics (49%), NSAIDs (18%), antiemetics (15%), and fluids (13%). No treatments were administered in 19 of 39 cases (49%). Amongst participating institutions, 69% reported fully vaccinating tigers for SARS-CoV-2 (≥ 2 doses). CLINICAL RELEVANCE Most SARS-CoV-2–infected tigers presented with mild to moderate clinical signs and recovered with limited to no treatment interventions. Asymptomatic SARS-CoV-2 infections can occur in tigers and may be underreported. Tigers vaccinated for SARS-CoV-2 remain susceptible to infection.