The laboratory diagnosis of Orthopoxvirus infection in the domestic cat

Twenty‐eight cases of naturally occurring feline Orthopoxvirus infection were diagnosed by combinations of virus isolation, electron microscopy, agar gel precipitation, histopathology and serology. Twenty‐five of 28 cases were positive by virus isolation on the chorioallantoic membrane of hens' eggs and in tissue culture, 22 of 28 by electron microscopy, three of five by histopathology, none by agar gel precipitation, and 17 of 17 by serology. The techniques used are described, and the results compared and discussed.