There are three forms of plague can affect the body. The most common is referred to as bubonic. Bubonic plague manifests after infected fleas have bitten a new host and the nearest lymph nodes have responded. This makes the lymph nodes swell and form infected lesions called buboes. The next type of plague infection is called septicemic. In this case, the virus spreads through the bloodstream to other organs and infects them. The final plague type is the rarest and also the most deadly, with 90 percent of untreated cases leading to death. It is called pneumonic plague, and it spreads through infectious respiratory droplets.

Plague occurs all over the world, but in the United States it typically is seen only in the southwest. Infected cats do cause a risk to both owners and veterinary staff. Extreme caution must be taken when plague is suspected, and immediate veterinary care is needed to save the cat’s life. 

Yersinia pestis infection causes what is commonly known as “plague” in mammals. It is carried by all types of rodents. Often, rodent fleas will spread the disease by feeding on an infected animal, transferring to another animal, and regurgitating infected tissue into the new animal. It can also be spread through bites, scratches, or coughs and sneezes from an infected animal, although this is less common. Cats are extremely susceptible to Y. pestis. 

The three different manifestations of plague have some symptoms in common, including: 

Additional symptoms vary with the nature of the infection:

All of the symptoms found in septicemic cases plus the following:

Fleas are the most common carrier of plague in mammals. Only rodent fleas carry Y. pestis. It should be noted that in areas where rodent fleas are common, dog and cat fleas are not common, and vice versa. All known causes are listed below.

Upon arrival to a veterinary clinic or animal hospital, a complete physical examination will be performed. The veterinarian will try to differentiate symptoms of plague with other bacterial infections. Microscopic examination will need to be made of blood, liver tissue, spleen tissue, lymph node tissue, lung tissue or bone marrow. If these samples test gram-negative and contain a “safety pin” like appearance, it is very likely that Y. pestis is present. 

Your vet will contact health officials to find the nearest testing center to send samples to. The samples must be frozen before being sent. The entire process can be completed in a number of hours. The sample should be taken before any antibiotics are given. It is possible in some cases to perform a swab if mouth lesions are present. This may be less invasive than collecting tissue samples. Feline leukemia virus and feline immunodeficiency virus should also be tested for and ruled out. 

Treatment should begin as soon as samples have been successfully collected, even before a diagnosis confirmation has been made. The sooner that treatment begins, the better chance of survival the cat has. 

Antibiotics 

The only successful way to fight against plague is by administering antibiotics. Streptomycin has the best success rate but is hard to come by in animal hospitals, as it is a human antibiotic. Gentamicin has also been proven to be effective. If the infection is still in its early stages and the cat is not experiencing complications, doxycycline may be prescribed. Tetracycline and chloramphenicol are other possible antibiotic options. At first, the treatments will be given through injection, but after three days of close monitoring in hospital, if the cat is responding favorably, an oral antibiotic will be prescribed and the cat will be sent home. After 72 hours of antibiotics, even pneumonic plague is considered to no longer be contagious.

Both the veterinary staff and the owners of the cat need to take extra precautions when handling a cat infected with plague. It can spread to humans, especially if the cat is suffering from pneumonic plague. Gloves and masks must be used when dealing with the cat. The cat will immediately be placed in isolation for diagnosis and treatment if plague is suspected. All materials that have come in contact with the infected cat need to be disinfected or destroyed. Anyone who has dealt with a cat infected with plague should monitor their own health for the following two weeks. 

The survival rate with treatment for cats infected with plague is only 50 percent. The best way to prevent infection is by regularly treating your cat for fleas. It is important to eliminate any rodent habitats and keep them out of your home. Keeping your cat indoors can also greatly reduce its exposure to Y. pestis. Continue at-home antibiotic treatment of an infected cat for 10-21 days as prescribed. Public health officials may also advise certain measures to be taken after an incident of plague. The cat owner may need a round of post-exposure antibiotics.