Canine distemper virus (CDV) is a significant threat to endangered wild felids.1 An ideal vaccination strategy has yet to be elucidated.2-3 Two methods for delivering a canarypox-vectored CDV vaccine to tigers (Panthera tigris) and domestic cats (Felis catus) were investigated. Eight tigers were divided randomly into two vaccination groups: subcutaneous injection or topical tonsillar application. Each received 2 ml of CDV vaccine (PureVax Ferret Distemper Vaccine, Merial, Duluth, GA, USA). Blood was collected from tigers on days 0, 21, 35 or 37, and 112 post-initial vaccination (PIV). Domestic cats were divided randomly into four treatment groups: saline injection, low and high dose oral, and subcutaneous vaccinates. Blood was collected from domestic cats on days 0, 7, 21, 28, and 165 or 208 PIV. Sera were tested for CDV antibodies by virus neutralization. All individuals were seronegative at the beginning of the study. One tiger vaccinated subcutaneously developed a titer of 32 by day 35, which reduced to 16 by day 112. Another tiger vaccinated by tonsillar application developed a titer of 8 on day 112. All other tigers remained seronegative. Cats that received saline injection or oral vaccination remained seronegative at each sampling time. Cats vaccinated subcutaneously developed titers ranging from 4 to >128 by day 28, and those re-bled beyond day 165 had titers of 16 or 64. The disparity in response between domestic cats and tigers may be due to species differences or a dose-dependent effect. Subcutaneous vaccination with canarypox-vectored PureVax Ferret Distemper is safe and elicits persistent antibody titers in domestic cats vaccinated parenterally.
1. Gilbert M, Soutyrina SV, Seryodkin IV, Sulikhan N, Uphyrkina OV, Goncharuk M, Matthews L, Cleaveland S, Miquelle DG. Canine distemper virus as a threat to wild tigers in Russia and across their range. Integr Zool. 2015;10(4):329–343.
2. Rodriguez K, Cushing AC, Bernal C, Ramsay EC, Gompf RE. Endocardial fibroelastosis in two related tiger cubs (Panthera tigris). J Vet Cardiol. 2018;20(1):73–77.
3. Sadler RA, Ramsay EC, McAloose D, Wilkes RP. Evaluation of two canine distemper vaccines in captive tigers (Panthera tigris). J Zoo Wildl Med. 2016;47:558–563.