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

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.