The word "plague" conjures up terrible images from the past, but in the veterinary context it refers to a relatively uncommon disease that primarily affects cats in the western and southwestern parts of the United States. The disease is caused by infection with the bacteria Yersinia pestis, which is frequently transmitted from wild rodents to pets through the bites of fleas or through the hunting of infected rodents. People that are in close contact with an infected pet can develop the disease, so despite the fact that plague is relatively uncommon, it is still very important.




Cats that have been infected with Yersinia pestis develop a high fever, become listless and lose their appetites, and can die. Different forms of the disease have additional characteristic symptoms. Bubonic plague is named for the swollen lymph nodes (i.e., buboes) that develop and may rupture and drain pus. Vomiting, diarrhea, weakness, difficulty breathing, and a cough may all be seen when the bacteria spread into the blood stream or to the lungs (i.e., the septicemic and pneumonic forms of the disease, respectively). To definitively diagnose plague, a veterinarian will need to send samples of blood, tissue, and/or pus to a diagnostic laboratory to be tested for the presence of the Yersinia pestis bacteria.




Despite its horrific reputation, plague is treatable. Pets should be hospitalized for antibiotic therapy, supportive care, and quarantine until their condition is stabilized and they can go home to finish their course of antibiotics. Regular use of effective flea control products and preventing cats from going outside and hunting potentially infected rodents is the best way to prevent plague in pets.


Written by: Jennifer Coates, DVM
Last reviewed: October 2, 2008