Feline Panleukopenia

By Malcolm Weir, DVM, MSc, MPH; Tammy Hunter, DVM; Ernest Ward, DVM

What is panleukopenia?

The term panleukopenia refers to a decrease in the number of all the white blood cells in the body. White blood cells play a major role in immunity and are important in defending against infections and diseases. In severe panleukopenia, white blood cell numbers may drop from the normal of several thousand per milliliter of blood to just a few hundred. This makes an affected cat extremely vulnerable to other infections.

What is the cause?

Feline panleukopenia (FPL), sometimes also called feline distemper, is caused by a virus of the parvovirus family known as feline panleukopenia virus (FPLV). A similar but distinct virus causes parvovirus disease in dogs. Parvoviruses are extremely tough viruses and are only killed by strong disinfectants, including 2% household bleach. FPLV can survive in some environments for a year or more.

How is this infection transmitted?

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.

"The virus is present in all excretions, particularly the feces, of infected cats."

What are the clinical signs of panleukopenia?

There is some variation in the clinical signs, but cats typically experience depression or listlessness, which may progress to collapse. 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. The hair coat quickly becomes dull and rough and the skin loses its elasticity due to dehydration.

Often, cats with panleukopenia develop other infections because their immune system is weakened. 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.

Can panleukopenia be treated?

As with most viral diseases, there is no specific treatment for FPL. Antibiotics do not kill viruses but help control the secondary bacterial infections that commonly develop due to the lack of white blood cells and the resulting reduced immunity. Dehydration and shock are life-threatening components of FPL, and intravenous fluid therapy and intensive nursing care are critical. If the cat receives aggressive supportive care through the initial stages of illness, the prognosis for a full recovery is good.

"...intravenous fluid therapy and intensive nursing care are critical."

How can I protect my cat against panleukopenia?

Fortunately, excellent vaccines are available and are part of the core feline vaccination program. Kittens require boosters of this vaccine starting at six to eight weeks of age and given every three to four weeks until the kitten is 16-20 weeks of age, followed by at least one booster a year later. Cats and kittens over 16 weeks of age need an initial series of two vaccinations three to four weeks apart.

The immunity produced by the panleukopenia vaccine is generally strong, but it decreases with time and at a faster rate in some cats than others; therefore, booster vaccinations every one to three years are strongly recommended. Your veterinarian will discuss the appropriate frequency of booster vaccinations for your cat's lifestyle. See the handout “Vaccines for Cats” for more information.

Are there any side effects to the vaccination?

"Modern panleukopenia vaccines are safe and side effects are extremely uncommon."

Modern panleukopenia vaccines are safe and side effects are extremely uncommon. However, as with all vaccines, some cats may be lethargic for a day or two after administration. Very rarely, a more severe allergic reaction, called anaphylactic shock, may occur due to a particular sensitivity of an individual to one or more components of the vaccine. Such severe reactions, if they occur, usually happen within a few minutes of vaccination, but may be delayed by hours in some cats. If you observe signs such as difficulty breathing, facial swelling, or any other signs of distress, call your veterinarian immediately.

Be sure to discuss any concerns you may have about vaccinations with your veterinarian.

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