"Epizootic" refers to a situation when a disease affects a large number of animals at the same time in a specific region. It is similar to an epidemic, but it refers specifically to animals rather than humans. Full definition
«Epizootic of beak deformities among wild birds in Alaska: An emerging disease in North America?» (dotearth.blogs.nytimes.com)
Williams BH, Kiupel M, West KH, Raymond JT, Grant CK, Glickman LT. 2000 Coronavirus - associated epizootic catarrhal enteritis in ferrets. (catvirus.com)
Wyatt, J.D., et al., «Human rabies postexposure prophylaxis during a raccoon rabies epizootic in New York, 1993 and 1994.» (voxfelina.com)