Not Just For Dogs

August 12, 2025

Cats Can Get Distemper Too

Nancy Kerr

When you hear the words “distemper” or “parvo,” you generally think of dogs; however, there is also a feline version. The disease is more commonly known as panleukopenia or feline distemper. “It has also been called cat fever, cat plague, feline agranulocytosis and feline infectious enteritis.”¹

What is Feline Panleukopenia?

“Feline panleukopenia is a highly contagious, often fatal parvoviral disease of cats worldwide. Feline panleukopenia is uncommonly encountered by general practice veterinarians in many countries, likely as a consequence of widespread vaccination. However, infection remains high in feral, free-roaming, and pet cat populations with limited access to preventive care, especially in areas with large numbers of kittens. Outbreaks are relatively common worldwide in animal shelters that house cats, especially when kittens are housed in groups and vaccination is not provided at intake.”²

Causes of Feline Panleukopenia

“Feline panleukopenia (FPL), sometimes also called feline distemper, is caused by a virus of the parvovirus family known as feline panleukopenia virus (FPLV).”³ The virus is transmitted via contact with an infected cat’s bodily fluids or contaminated environment and is extremely contagious. “The virus is present in all excretions, particularly the feces, of infected cats. A susceptible cat can be infected by direct contact with an infected cat, or the virus can be transferred via contaminated water, food bowls, or on shoes and clothing. The incubation period from infection until clinical signs develop is typically three to five days, seldom longer than a week.”³

“In parvovirus-infected animals, infectious viral particles are abundant during the acute phase of illness in all secretions and excretions, including vomitus, saliva, urine and feces, and can be detected in the feces of survivors for up to 6 weeks after recovery, although most patients stop shedding after 2 weeks.”² The virus can also survive on surfaces for a long time, and is unaffected by many household cleaners, except bleach.

An infected cat can infect other cats who come into contact with its blood, urine, or feces. “Unvaccinated cats who come into contact with contaminated surfaces, such as bedding, cages, food dishes, litter boxes, and other surfaces, are at risk of contracting the virus, even if they don’t come into contact with an infected cat.”¹ This makes it important for unvaccinated cats to be kept away from areas where an infected cat has been. “Additionally, fleas can carry the disease from an infected cat to another unvaccinated cat.”¹ If humans do not wash their hands or change their clothes after handling an infected cat, the disease can be transmitted via contact to an unvaccinated cat.

Symptoms

If you suspect that your cat has feline panleukopenia, seek veterinary care immediately to provide the necessary treatment and recovery support. The longer that a cat is infected with the disease, the chance of survival decreases. Feline panleukopenia can be mistaken for other illnesses. E. coli infection from eating contaminated raw food can present the same symptoms. It is important to let the vet know if you are feeding raw food so that it can be ruled out. Some of the symptoms may not be noticeable right away, as cats are good at hiding pain.

“Since the virus infects and destroys rapidly growing cells, the intestinal tract is often affected. Vomiting and diarrhea are frequent, and diarrhea may contain blood. Other symptoms include: rough coat.”³They may show signs of loss of appetite dehydration, (with sunken eyes), dry gums, and excessive thirst. Neurological symptoms like tremors, seizures, and lack of coordination can also manifest in feline panleukopenia cases.”⁴

Panleukopenia weakens a cat’s immune system, which can often lead to developing other infections. They may have “purulent (green/yellow) discharge from the eyes and nose. In young kittens with severe infections, sometimes the only clinical sign is sudden death.”³ Some cats die after being very sick, while others only have mild symptoms or do not show typical symptoms.

“A fever may happen during this early stage and rise to a high level. In advanced disease, the cat’s body temperature may fall to lower-than-normal levels. Low internal temperatures can be a sign of impending death.”⁵ In severe cases, sudden death can happen.

Diagnosing

With symptoms varying from mild disease to severe illness or even fatality, diagnosing feline panleukopenia is sometimes difficult. The symptoms can often be confused for symptoms of “pancreatitis, poisoning,”¹ “salmonella or campylobacter infection, a feline immunodeficiency virus (FIV) infection, a feline leukemia virus (FeLV) infection,”⁵ and other illnesses.

It is important that it gets properly diagnosed since a cat can become very sick. A blood test will be conducted to determine how many white blood cell types are present. Reduced white blood cells may point to a feline panleukopenia infection, and “the blood test would show a reduced number of all cell types (pancytopenia), a characteristic of feline parvovirus disease.”⁵ If a cat is dehydrated, it may make it difficult to get a sample to do the blood work. “Other diagnostic tests may include: IDEXX SNAP test, blood smear, necropsy, biochemical profiling.”¹ “A complete blood count (CBC) is crucial to assess the white blood cell count, which is typically low in affected cats.”⁴ A veterinarian may also order stool tests to diagnose this disease. The laboratory may identify the virus in the cat’s stool.

If a cat is exhibiting symptoms for feline panleukopenia, a negative IDEXX SNAP test result does not mean the cat is out of the woods. It is possible to have a false negative test result. Additional SNAP tests may need to be done over a period of time. “Additionally, a polymerase chain reaction (PCR) test can detect the presence of the virus in the bloodstream or feces. In severe cases, further diagnostics like imaging studies or antibody testing may be necessary to confirm the diagnosis.”⁴ Early detection is key to successful treatment and management. A presumptive probable diagnosis of feline panleukopenia can be performed after death by a PCR test.

Types of Feline Panleukopenia

There are three forms of the feline panleukopenia virus: classical, atypical, and subclinical.

“Classical feline panleukopenia is the most common form of the disease and is characterized by symptoms such as fever, lethargy, vomiting, diarrhea, and a decreased white blood cell count. Atypical feline panleukopenia may present with unusual symptoms such as neurologic signs, including tremors, seizures, and wobbly gait, in addition to the typical gastrointestinal signs. Subclinical feline panleukopenia where some cats may be infected with the virus but show no outward signs of illness, which make diagnosis challenging without specific testing.”⁴

Treatment

Early detection and prompt treatment are crucial in managing feline panleukopenia and improving the chances of recovery for affected cats. There are no medications that can kill this virus. Infected cats will require supportive care which typically includes hospitalization, intravenous fluids, medications to control vomiting and diarrhea, and antibiotics to prevent secondary infections. In severe cases, blood transfusions may be necessary to help the cat’s immune system fight the virus. Isolation to prevent the spread of the virus to other cats is crucial during treatment. Regular monitoring and\or trips to the vet is essential to monitor the cat’s recovery.

“Successful treatment of acute cases of feline panleukopenia is challenging. When disease is severe, resources are limited, or risk of spread to vulnerable populations is high, poor prognosis for survival and concern over patient welfare should prompt strong consideration of humane euthanasia. Electrolyte disturbances (especially hypokalemia), hypoglycemia, hypoproteinemia, anemia, and opportunistic secondary bacterial infections often develop in severely affected cats. Anticipation of these possibilities, close monitoring, and prompt intervention may improve outcome.”²

“Poor prognostic indicators for cats with panleukopenia include hypothermia, low body weight, severe leukopenia, thrombocytopenia, hypoproteinemia, and hypokalemia. Positive prognostic indicators include WBC rebound and return of appetite.”² Kittens have high mortality rates, while older cats have a better chance of surviving.

Complications

The disease is also dangerous for unborn kittens and can cause lasting complications. “In pregnant queens, FPLV not only affects the queen’s health, but also spreads transplacentally to cause embryonic resorption, fetal mummification, abortion, stillbirth, and dystocia. Infection in the perinatal period may destroy kittens’ rapidly dividing cerebellar or retinal cells, leading to cerebellar hypoplasia, incoordination, and tremors that persist throughout life.”²

Preventing

The most effective way of protecting your cat is by vaccination. Veterinarians will usually advise to start vaccination at the age of 8 or 9 weeks. Two or three doses, three to four weeks apart, are recommended. The last of these should not be before the age of 20 weeks. A follow-up dose at 26 to 52 weeks is now recommended.

Adult cats can also get the feline parvovirus. They should get the booster doses of the vaccine regularly. Both live and killed vaccines are available and are very effective. The more time that has passed since they were vaccinated, the chances of getting the disease increase.

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