Feline Panleukopenia: Protect Your Cat from this Often Fatal Disease

Feline Panleukopenia (sometimes referred to as feline distemper) is an extremely contagious and often fatal disease of cats. It can also infect non-domestic felidae and other animals such as raccoons and certain members of the weasel family such as mink. It does not affect dogs.

What are the causes of panleukopenia?
Feline panleukopenia is caused by a virus closely related to canine parvovirus infection (some strains of canine parvovirus can infect cats) and like parvovirus of dogs the virus can persist in the environment for a year or more. Once a commonly seen disease, panleukopenia is now relatively uncommon in large part because most domestic cats are vaccinated and the vaccine is very effective. Nonetheless, the disease persists among unvaccinated cats. As is the case with parvovirus in dogs, the feline form of the disease is transmitted in bodily fluids and can persist in the environment. Transmission (on shoes and clothing) and environmental contamination can be greatly reduced with simple hygiene1.

What are the signs of feline panleukopenia?
The disease occurs primarily in young cats and kittens and causes severe depression and lethargy as well as fever, vomiting and diarrhea. Affected cats may have a very low white blood cell count (hence the name panleukopenia). Many cats undergo a subclinical infection and do not show signs at all. Not all exposed cats become clinically ill but exposed cats as well as cats that survive the full-blown disease have long-term immunity after their infection.

How can cats become infected by feline panleukopenia?
The route of infection is primarily oronasal exposure to secretions or excretions or infected animals or environment. The virus quickly enters the blood stream and spreads to all parts of the body. The disease is frequently fatal with a mortality rate as high as 75 percent in untreated cats. Complete recovery can take several weeks2.

How is feline panleukopenia diagnosed?
A presumptive diagnosis can be made based on history and clinical signs as well as a very low white blood count. More sophisticated tests may be employed in large outbreaks but are not generally needed.

What are the treatments for feline panleukopenia?
Because this is a viral disease, treatment is largely based on the symptoms until the patient begins to recover and usually consists of, in severe cases, hospitalization for intravenous fluid therapy and antibiotics. The most severe symptoms occur in the first 5-7 days.

What is the prognosis with feline panleukopenia?
Though if untreated the disease can be fatal, early aggressive therapy is often successful. In cats that do survive, reinfection does not recur, ie, they have life long immunity.

How can feline panleukopenia be prevented?
There is a very effective and very safe vaccine available that has significantly reduced the incidence of panleukopenia. All cats should be vaccinated in accordance with the recommendations of the American Association of Feline Practitioners and your veterinarian.

As with many diseases the answer lies in early and complete prevention by means of effective vaccination procedures. Be sure to discuss this and other vaccine recommendations as part of your cats overall wellness program.

If you have any questions or concerns, you should always visit or call your veterinarian -- they are your best resource to ensure the health and well-being of your pets.

1. "Overview of Feline Panleukopenia." Merck Veterinary Manual. July 2013. Web.

2. Scott, Fred W., DVM, PhD., and James Richards, DVM. "Feline Panleukopenia Virus." Max's House. Web.

Control in specific situations


Random source populations with unknown vaccination histories, continuous turnover, and high risk for infections characterize most shelters. The cost of a vaccine is a significant management aspect therefore, only those antigens that demonstrate a clear benefit against common and significant shelter diseases should be considered.

Feline panleukopenia is such a disease. FPV has re-emerged as a cause of cat mortality in cats in shelters and rescue homes throughout Europe and the United States. With rare exceptions, all kittens and cats over 4 to 6 weeks of age should therefore be vaccinated, regardless of their housing status. - For sick or pregnant cats, any decision about vaccination has to be taken for the individual cat, but vaccination is recommended whenever and as soon as justifiable. Pregnant cats should never receive a live FPV vaccine. Alternatively passive immunisation with FPV antiserum may be considered (or anti-CPV-2 canine globulin). Kittens should be vaccinated beginning at 4 weeks of age in the face of an outbreak, otherwise at 6 weeks of age. MLV vaccines are recommended because of their faster onset of action, greater efficacy at overcoming maternal antibody, and a greater likelihood of conferring sufficient immunity. Although concerns have been raised regarding strain reversion to virulence, this has never been documented. Vaccination should be repeated every 3 to 4 weeks until 16 weeks of age. If adult cats are ill or otherwise compromised at the time of initial vaccination, another injection should be considered when the cat is again in good health (at least two weeks after the initial vaccine). - Cats of unknown status should not be housed together.

Passive immunisation can be used in shelters when available. It is useful at admission if other diseases are present or in an environment with high infection pressure, as it provides immediate protection. The efficacy of immunoglobulins to prevent infection, including FPV, has been proven in experimental studies and in the field some 50 years ago. It depends upon the antibody titre against the specific agent, the volume administered, the importance of antibodies in controlling a particular infection, and the timing of administration.

Multivalent hyperimmune immunoglobulin preparations for cats are commercially available in some European countries - horse sera containing antibodies against FPV, FHV-1, and FCV. They are marketed for prophylactic (usually one injection of 1 vial/animal subcutaneously) and therapeutic (usually 3 injections of 1 vial/animal subcutaneously every 24 hours) use. Protection lasts for about 3 weeks. During this period, active immunization (vaccination) must be avoided, because the immunoglobulins will bind to the vaccinal antigens, tying them up in immune complexes. Although large amounts of foreign protein are administered, allergic reactions and side effects are rare if a cat is treated for the first time. Repeated treatment (with an interval of more than 1 week) is discouraged because cats can develop anaphylactic reactions to the equine protein (Hartmann and Hein, 2002).

Customised homologous (hyper)immune serum can be prepared and administered. Serum is obtained from healthy cats or from groups of animals that have recovered from a disease, whereas hyperimmune serum comes from animals that had been repeatedly vaccinated. The antibody content and hence the duration of protection of such sera are unknown.

Like all exogenous proteins, administered antibodies are quickly eliminated from the body.

Feline immune sera can be prepared in veterinary practice, but the blood donors must be screened for insidious infections (e.g. FIV, FeLV, Bartonella infection). The blood type of donor and recipient should match. The minimum amount required for protection is unknown, but the dose recommended for cats is 2 to 4 ml serum per kilogram body weight. Attention must be paid to sterility during collection, storage and administration. Jugular vein puncture is preferred, and the area over the jugular vein should be shaved and disinfected. Blood should be collected (at least twice the amount of required serum) into sterile tubes without additives and allowed to clot. Serum can be stored at -20° C in single dose aliquots, as IgG is very stable, and can be kept for up to a year if frozen promptly after collection (Levy and Crawford, 2000 EBM grade II). Usually, sera are given subcutaneously intraperitoneal injection is more feasible in kittens. If for an instant effect intravenous administration is required, plasma (instead of serum) should be used (Greene and Schultz, 2005). For details see the ABCD Guidelines Blood transfusion and Pennisi et al. (2015).

As FPV and CPV are closely related viruses that a high degree of cross-neutralization, it may be expected that hyperimmune sera raised against CPV are also effective against FPV. This is of particular importance in countries where commercial anti-FPV serum is not available. The remarks above about heterologous preparations apply.

Epidemiology and risk factors

FPV is found worldwide, and all members of the Felidae family can be infected. Young cats and kittens are most commonly affected, though cats of all ages are susceptible. FPV is predominantly a fecal-oral agent but can be spread in other secretions and urine.

FPV is a profoundly contagious pathogen and is particularly a problem for premises of high-throughput, densely populated numbers of cats of variable vaccination status, for two main reasons.

Firstly, infected cats shed enormous numbers of FPV virions. Shedding often only lasts a few days, but can occur both before, and up to 6 weeks after the onset of clinical signs. Secondly, as a non-enveloped virus, FPV can survive in the environment for a staggering one year, highly resisting degradation by UV light, desiccation, and some popular disinfectants.

Cats most likely to acquire FPV infection are:

  • Under 1 year of age
  • Stray or sheltered
  • In boarding catteries
  • In pet stores
  • Unvaccinated

Control and prevention of FPV infection

Environmental control of FPV is essential to successful control and prevention. When de-contaminating surfaces, food bowls, litter trays and other fomites, the correct choice of disinfectant is critical.

Quaternary ammonium compounds are ineffective against FPV. Sodium hypochlorite (i.e. bleach)-based products are highly efficacious. However, bleaches stain equipment, and are vulnerable to inactivation by organic debris. Potassium peroxymonosulfate (e.g. Virkon™) avoids these issues and reliably destroys FPV.

In veterinary clinics, hospitalised FPV-infected cats should be strictly isolated to prevent new nosocomial cases. Isolation should be 4-6 weeks given the possibility of shedding the virus for this period. Many cats will be discharged before this, so owners should attempt temporary social isolation at home, especially from young cats and kittens.

Feline Panleukopenia: Protect Your Cat from this Often Fatal Disease - pets

Feline Distemper


The feline distemper virus amounts to a single strand of DNA surrounded by a protein coating. It is extremely stable in the environment, which leads to its characterization as “ubiquitous.” It can last a year indoors at room temperature. It survives freezing as well as treatment with such common disinfectants as alcohol and iodine. Fortunately, soaking a surface in bleach (diluted 1 part bleach in 32 parts water) for 10 minutes will kill it.

Virtually every cat will be exposed to this virus.

Infection occurs when the virus enters the body through the mouth or nose of the victim. Whether illness results or not depends on the immunity present in the victim vs. the number of individual virus particles (i.e. the amount of virus) entering the body.

Image of the Feline Panleukopenia Virus

(Photocredit: Public Domain via Wikimedia Commons )

The feline distemper virus is a “parvovirus.” Many people are familiar with this term as parvovirus infection is a very real concern for dogs, especially puppies. In fact, canine parvovirus is very closely related to the feline distemper virus and much of the information regarding canine parvovirus holds true for feline distemper. The feline distemper virus, however, is more difficult to remove from the environment and more lethal in its victims than its canine counterpart.


An infected cat sheds large amounts of virus in all body secretions including feces, vomit, urine, saliva, and mucus. The virus persists long after evidence of the original body secretion has faded away. The virus enters the victims body and proceeds to infect rapidly dividing cells. The lymph nodes of the throat are first and from there, over the next 2-7 days, the virus rushes to the bone marrow and intestine.

In the bone marrow, the virus suppresses production of the entire white blood cell line, hence the term “panleukopenia” (literally, “all-white-shortage”). The white blood cells are the immune cells that are needed to fight the infection and without them the victim is completely vulnerable to the advance of the virus.

In the intestine, the virus causes ulceration leading to diarrhea and life-threatening dehydration as well as bacterial infection as the barrier between the body and intestinal bacteria is lost. The patient dies from either dehydration or secondary bacterial infection.

Because most cats are exposed to this virus to some extent, it is unusual for a kitten to have no immunity whatsoever. Further, the vaccine is so effective that even one dose can provide long lasting protection. As a result, infection is largely limited to unvaccinated younger animals kept in groups (which corresponds to exposure to amounts of virus large enough to overwhelm their partial immunity). Mortality of the sick is typically considered 90%, though it has been said that a kitten that survives the first 5 days is likely to survive the infection.

Recovered kittens are considered contagious for six weeks following recovery.


(original graphic by

A special syndrome occurs if infection occurs during pregnancy. If infection occurs in mid or early pregnancy, the kittens simply abort. If the kittens are fairly far along, the cerebellum is involved, leading to cerebellar hypoplasia. The cerebellum is the part of one’s central nervous system that coordinates balance and movement, enabling one to walk or run on an uneven surface without consciously thinking about it. Without a normal cerebellum, the kitten is born with marked “intention tremors:” whenever he focuses on purposeful movement, he tremors so much that normal movement is impossible. Such kittens are called "Wobbly Cats" and are notably abnormal but are considered to have good life quality and can be kept as pets as long as they are looked after.

For more details on Cerebellar Hypoplasia click here.


Any kitten with fever, appetite loss, diarrhea, and/or vomiting is a suspect for feline distemper. Classically, a white blood cell count shows almost no white blood cells there are very few causes of white cell counts this low and the infection can be considered confirmed.

The SNAP Fecal ELISA test kit made for canine parvovirus is often used in cats as a means to reaching a diagnosis. This test detects the presence of parvovirus in stool and is felt to be accurate though the test is not specifically labeled for this use by the manufacturer. Vaccination 5-12 days prior to running the test can lead to a positive test as the virus from the vaccine will be detected. It is important to keep this information in mind when using this test to make a diagnosis recent vaccination will cause a false positive.

If a dead kitten is available for necropsy (“autopsy” in animals is called a “necropsy”), the infection is readily confirmed by biopsy as there are unique tissue findings in feline distemper.

Virus isolation, PCR testing, and antibody level measurement are also potential tests for feline distemper.

The IDEXX snap test kit for parvo,
one of the most popular ELISA kits
(original graphic by

The infected cat can recover if he/she can be kept alive until his/her immune system recovers from the panleukopenia and can throw off the infection. This means that invading intestinal bacteria must be kept at bay with antibiotics and aggressive fluid therapy must control dehydration. Hospitalization is required as fluids and medications must be given intravenously. Blood sugar must be supported as well and control of pain, nausea and hypothermia is crucial. This is essentially the same therapy as for canine parvovirus infection, though the feline experience seems to be more lethal. There is little chance of survival without hospitalization.

If a cat is lucky enough to recover from this infection, generally no permanent damage is retained and the cat goes on with lifetime immunity.

  • Virus is shed for up to 6 weeks after recovery.

There is no way to adequately disinfect the environment a new cat should simply be vaccinated.

Vaccination after age 12 weeks is generally effective in generating immunity against this infection, though immunity gained from mother’s milk may inactivate the vaccine through age 14-16 weeks. Most vaccine protocols call for at least two doses of vaccine to be given 2-4 weeks apart with the last dose being received at or after age 14 weeks.

  • Vaccination, at least with a live vaccine, should be avoided during pregnancy as cerebellar hypoplasia (see above) can result in the kittens.

Vaccination is generally given every 1-3 years depending on the protocol of the animal hospital. Vaccination can be given in a nasal form or in an injection (either modified live or killed virus vaccine) given in the right front leg area. Killed virus vaccine has been associated with development of vaccination-associated fibrosarcoma (an aggressive cancer) in rare individuals. Research is continuing in this area.

Marion Animal Hospital

Feline Panleukopenia Virus (FPV) is a viral disease of cats. It is also known as “Feline Infectious Enteritis”, “Feline Distemper”, “Feline Ataxia”, or “Cat Plague”. It is highly contagious and life-threatening. The name, panleucopenia, is derived from the low count (leucopenia) of white blood cells (leucocytes in the immune system) characteristic of affected animals. The virus attacks primarily the intestinal tract, bone marrow and stem cells of the developing fetus. Specifically, it attacks the rapidly dividing blood cells in these tissues, meaning infection often leads to anemia and the animal becoming highly susceptible to secondary viral or bacterial infections.

FPV is one of the most significant feline diseases in the non-vaccinated population. The virus is highly resistant and can survive for years in contaminated environments. This means that vaccination is the best prevention measure for your cat. Kittens between 2 to 6 months of age, pregnant cats and immune compromised cats are at the highest risk of developing severe symptoms. In adults cats, FPV generally occurs in only mild form and may not show any symptoms. Cats which survive an FPV infection develop immunity to any further infection with the virus.

The virus causing FPV is related to the canine parvovirus as they are both in the genus Parvoviridae, however, the feline parvovirus can not be transmitted from cats to dogs, or vice versa.

Complete loss of interest in food or water (may hang head over bowl but not drink or eat)
Hiding for several days
Tucking feet under the body for extended periods
Resting chin on the floor for extended periods

Diarrhea (often contains blood)
Anorexia (weight loss)
Poor coat condition
Ataxia (other neurological symptoms if the virus attacks the brain)

FPV is caused by the feline parvovirus which is transmitted by contact with infected blood, feces or urine. The virus can also be transmitted by fleas that have been feeding from an infected cat, or by humans who have not washed their hands between handling cats, or by equipment that has been used by other cat such as bedding or bowls. Proper human hygiene, e.g. using soap and water during hand-washing after handling each animal, minimizes the possibility of transmitting the infection to healthy animals.

The feline parvovirus can survive and persist on many surfaces. It is therefore important to practice safe methods to effectively clean the cat’s environment, including its handlers, to reduce the possibility of transmission. Even with these precautions, the virus may persist in environments where an infected cat has been. Establishments which house large numbers of cats (e.g. shelters and kennels) may harbor the virus.

Kittens can acquire FPV while in the uterus if the pregnant mother is infected, or, through her breast milk during nursing. The prognosis is generally poor for kittens which have contracted the disease whilst in the uterus.

Because cats tend to go outdoors more during summer, the disease is more likely to be transmitted during this season.

If you suspect your cat has FPV, your veterinarian will require a thorough history of her health and recent activities. This will include whether your cat has recently been in contact with other cats, or if she is allowed access to the outdoors.

FPV symptoms can be similar to several other diseases including poisoning, pancreatitis, feline leukemia, feline immunodeficiency virus and others. It is therefore important to give as much detail as possible to your veterinarian so that appropriate treatment can start quickly.

The veterinarian will initially perform a physical examination. If necessary, blood tests will be taken for a complete blood count and biochemistry profile, and possibly a urine test for urinalysis. The feline parvovirus attacks and kills cells that divide rapidly, such as those in the intestine and those produced in the bone marrow. An infected animal will typically have a blood count that is low in white and red blood cells. Microscopic examination of feces may reveal remnants of the virus.

Cats infected with FPV are likely to require immediate treatment. Because dehydration is one of the primary symptoms, the major aim is to restore body fluid levels to normal values and maintain these, along with appropriate electrolyte balance. It is critical this is done quickly as the dehydration can quickly become life endangering. Because the virus compromises the immune system, your cat may have to take antibiotics to reduce the possibility of opportunistic bacterial infections.

Your cat will need to be rested during her recovery. Provide a warm and quiet space away from other animals and children. Avoid her exerting herself by placing food, water and the litter tray close to her recovery bed. Isolate the infected cat from others, however, maintain your own physical contact with the cat as the probability of your cat’s recovery are increased by receiving affection from you this infection has an extremely depressing effect on both the mental and physical health of your cat and your cat ‘s recovery will benefit considerably from your affection and comfort. Strict hygiene is essential. Remember that the virus can remain infective on surfaces and people which handle an infected cat should stay especially clean to avoid transmitting the virus to other cats.

If your infected cat is treated effectively and quickly, and survives the first 2 days, it is likely she will make a full recovery. It may take several weeks for your cat to return to complete normality, but once she has, she will have a life-time immunity to FPV and will not transmit the virus after the initial infection.


Follow your veterinarian’s advice with regards medication, isolation of your cat and household disinfection. Closely observe your other cats for signs of illness and discuss with your vet, the possibility of vaccinating other cats in the home.

Although household bleach is an effective disinfectant against the FPV virus, replacing all items associated with an infected cat is the best way to ensure any traces of the virus have been removed. Remember that although your infected cat will not be susceptible to re-infection, other cats can easily be infected by contaminants that remain.

The most important action in the prevention of FPV is vaccination. Ensure you ask your veterinarian to include the FPV vaccine in any vaccination program for your cat. Non-vaccinated, pregnant cats have a compromised immune system and are therefore highly susceptible to fatal complications. If the developing fetuses become infected with FPV, they are very likely to have severe developmental dysfunctions at birth.

Watch the video: Infectious Disease - Feline Panleukopenia Shelter Medicine Group Final (May 2021).