Group G streptococcal epizootic in a closed cat colony.

An epizootic of beta-hemolytic Lancefield group G streptococcal infections occurred in a specific-pathogen-free colony of laboratory cats. A total of 19 out of 68 animals in a single building were affected over a 10-day period. Clinical signs included fever, depression, lymphadenopathy, pharyngitis, and submandibular edema. The organism was recovered from the pharynx in two of five clinically normal cats from the affected building. Cultures from 12 animals in the same colony but housed in unaffected buildings were negative. Two doses of long-acting penicillin G 72 h apart stopped the outbreak and resulted in negative cultures for previously affected animals. Three months later, two new cases occurred in the same building. The disease was finally eradicated from the colony by depopulating the affected building.