Feline Panleukopenia (Feline Distemper): Symptoms and Treatment

Medically reviewed by: Kinga Wojtczak, Doctor of Veterinary Medicine, specialist in canine and feline diseases

Panleukopenia in cats is a very dangerous viral disease, also known as feline distemper, in which kitten mortality can reach 100%.

Did you know that you, too, can infect your cat with the panleukopenia virus?

In this article, you will learn why feline panleukopenia is so dangerous and how to prevent the disease. I will also explain how to tell that your cat has been infected with the virus, and what the treatment and outlook for a kitten are. I encourage you to read the whole article. By a twist of fate, a tiny ball of fluff just a few weeks old turns up at your home. A little boy or a little girl. Its origins vary, and so do its parents…

Its immune status—either known, or still "to be built". At first, it is usually very active, eager to play and to eat. The litter box is found without trouble and, apart from one or two soft or cow-pat-like stools, everything is usually firm and neatly done in the litter box. But one day, a few days after arriving in your home, the little furball is listless, has vomited in several places, and does not want to eat or play.

There is more than one loose, mushy stool in the litter box. The color is strange too—not a normal stool color, but yellow, and you can often smell all too clearly that it is feces, because the odor is often downright repulsive. The best thing you can do then is to pack up the sick little furball and rush to the veterinarian. You may ask why—maybe it will pass on its own? No, it will not pass—it will get even worse—and the little meowing furball may die, because of the risk of infection with the panleukopenia virus.

• What is panleukopenia in cats?
• How can a cat become infected with the panleukopenia virus?
• How does feline distemper develop?
• Feline panleukopenia symptoms
• Diagnosis when panleukopenia is suspected
• Feline panleukopenia treatment
• What can I do to protect my cat from feline distemper?
• When can I bring a new cat into a group of cats that has had panleukopenia?
• Summary

What is panleukopenia in cats?

Feline panleukopenia is a viral disease closely related to the viruses of canids—to the parvovirus of dogs and other canids.

It is also known as:

• feline typhus,
• feline distemper,
• feline infectious enteritis,
• feline agranulocytosis.

Working against us is the fact that the panleukopenia virus is very hardy in the environment. In a spot where a carrier animal has passed feces (that is, outside the body), it can survive for as long as a year! It is very hard to eliminate: most chemical disinfectants cannot kill it, and neither high nor low temperatures can destroy it.

The virus is inactivated only after 10 minutes of exposure, at room temperature, to:

• 6% sodium hypochlorite,
• 4% formaldehyde,
• 1% glutaraldehyde.

All of these substances are toxic to both animals and humans.

How can a cat become infected with the panleukopenia virus?

Kittens up to 4 months of age are the most susceptible to the panleukopenia virus and its consequences. This is linked to the development of their own immunity and the waning of the immunity they acquired from their mother. When a group containing kittens of this predisposed age is exposed, the morbidity rate among susceptible animals can reach 100% of the kittens. Not all of them will show the full range of signs.

All felids are susceptible to infection and disease. Susceptibility has also been found in mink (mustelids) and raccoons (procyonids). As with most viral diseases, the source is sick cats and asymptomatic carriers, and in particular their feces.

Testing can also detect the virus in:

• saliva,
• vomit,
• excreta,
• blood.

Another danger is that virus shedding itself lasts 1–2 days, but the virus can still be passed in excreta, saliva or blood for up to 6 weeks after recovery! Transmission from the mother, in utero at any stage of pregnancy, is also possible. Infection can also occur through external parasites—mainly fleas. The route of infection is oral, but the intranasal route has also been found. Direct contact with feces is not necessary.

Unfortunately, we ourselves can also contribute to infection through indirect contact. This can happen if we have previously held a sick kitten in our arms or it has been on our clothes, or if we have stepped in such an animal's feces (remember that the virus can survive for a year in the environment).

How does feline distemper develop?

After oral or intranasal contact with a source of the virus, the virus enters the body. It replicates (that is, the virus multiplies by copying itself) in the lymphoid tissue of the mouth and throat (tonsils, salivary glands). This takes up to 24 hours after the virus enters the body. The virus then spreads to all tissues of the body (viremia), which happens between day 2 and day 7 after the virus enters.

The panleukopenia virus shows tropism (a preference for particular tissues).

It settles and multiplies in tissues with a high rate of cell division, that is:

• lymphoid tissue,
• nervous tissue,
• bone marrow,
• the epithelium of the intestinal villi and crypts.

In cats with weakened immunity, that is, cats without enough antibodies or without antibodies of adequate quality, the incubation period lasts from 2 to 10 days, but most often about 5 days. Damage develops in the rapidly dividing cells listed above. At the same time, immunity drops, and the risk of secondary infections, poisoning by bacterial toxins and signs of shock increases.

Meanwhile, the lining (epithelium) of the small intestine is destroyed, in particular the intestinal villi and crypts and their epithelium. These disturbances lead to the characteristic signs the owner notices—vomiting in cats as a consequence of secondary intoxication, and foul-smelling, watery diarrhea in cats resulting from the inability to digest and absorb food and from secondary bacterial infections.

In the case of in utero infection, there are several possible scenarios, depending on the stage of pregnancy at which the infection occurred:

• If the pregnancy was at an early stage and the queen was not vaccinated, fetal death and resorption of the fetus occur. In the queen, this often shows up secondarily as infertility.
• If contact with the virus occurred in the second half of pregnancy, we may find mummified fetuses or abortion and stillborn kittens.
• If the infection occurred toward the end of pregnancy, the newborn kittens show either developmental disorders of the eyeball (retinal defects) or disorders affecting the cerebellum. These disorders show up as problems with movement in the kittens, loss of balance, blindness and hydrocephalus. We may also see inflammation of the heart muscle (myocarditis), even in newborn kittens, often with sudden cardiac death. These changes are recognized at necropsy or after testing for panleukopenia in a specialist laboratory.

Feline panleukopenia symptoms

In clinical practice, several forms of feline panleukopenia are seen. The most severely affected are young animals without adequate immunity, that is, most often unvaccinated kittens or kittens in the period when maternal antibodies wane (if the queen was vaccinated, she passes her antibodies on to the kittens). These are usually kittens up to 4–5 months of age. They also develop the most severe forms of the disease, with mortality reaching over 70%.

In the peracute form, infected kittens die, even without clinical signs, within 12 hours of contact with FPV (feline panleukopenia virus). Such kittens cannot be saved; mortality then reaches up to 100% of the litter.

In the acute form, you will most often notice:

• reluctance to play,
• vomiting,
• reluctance to eat,
• general lethargy.

Diarrhea is common; later on it becomes foul-smelling and yellow and often contains blood. In kittens, the veterinarian may find a very high temperature during the examination—up to 41°C. If sepsis develops (multiplication of viruses or bacteria in the bloodstream), body temperature may even drop very low, and multiple organ failure and death of the animal may occur.

Kittens with a better immune status (more resistant) or older kittens, over 5 months of age, usually show milder signs, and their survival rate is much higher. Recovery after panleukopenia takes several weeks. During this time, any infection is a threat to them.

If a pregnant queen becomes infected, what you may see is mainly:

• the birth of dead or abnormal fetuses,
• infertility (unsuccessful matings), or
• kittens showing various defects, mainly of the nervous system: wobbling, blindness, deafness, paralysis, circling.

As the kittens grow, further defects may appear, or existing ones may get worse.

In adult cats with panleukopenia, or when an older cat is infected with the feline distemper virus and its immunity, though fully developed, has been weakened by various factors, signs of transient gastrointestinal upset may appear, that is:

• vomiting,
• diarrhea,
• sometimes lethargy,
• transient loss of appetite.

These signs usually resolve on their own, and sometimes you may not even notice them.

Diagnosis when panleukopenia is suspected

Whenever our patients have gastrointestinal signs, we veterinarians must find out what we are dealing with.

At every visit, we perform a thorough physical examination of the animal, including:

• examination of all accessible mucous membranes,
• examination of the lymph nodes,
• taking the temperature,
• palpation of the abdomen.

Sometimes additional tests are needed—blood tests, ultrasound or X-rays , or rapid in-clinic test kits for quick diagnosis. First, we must rule out foreign bodies and worm infestation. Next, we rule out poisoning by toxic plants (here you really need to know which plants you have at home). Rapid in-clinic test kits for infectious diseases are very helpful in diagnosing feline infectious enteritis.

With them, we have a result within a few minutes and know whether we are facing this terrible, hard-to-treat disease, feline distemper.

Feline panleukopenia treatment

Our task is to correct the acid–base balance as quickly as possible, that is, to prevent dehydration. Depending on how advanced the disease is and on the degree of dehydration, we choose suitable fluids for intravenous administration. We also give antibiotics to prevent secondary infections, antiemetics and drugs that protect the gastric and intestinal mucosa. An important element is giving a probiotic, so that the intestines are colonized by normal bacterial flora.

The ideal option is to give serum as soon as possible, but it is not available in Poland… Sometimes serum from convalescent cats comes to the rescue, that is, from cats that had panleukopenia a few weeks or months earlier and produced their own antibodies. Serum against feline distemper should be given to all at-risk animals in the group.

Remember that the veterinarian tailors treatment to the kitten's current health and clinical signs. Your cooperation is very important in treatment—caring for the kitten or the group of cats and following the veterinarian's instructions.

What can I do to protect my cat from feline distemper?

The most important factor protecting kittens from the disease is regular vaccination. Even kittens that will never go outdoors are at risk of infection, for example from your clothes or shoes. Kitten vaccination is given as a primary vaccination series, started after effective deworming. Kittens are usually vaccinated with a combination vaccine that includes components against feline upper respiratory disease (you can learn more about it in the article "Feline upper respiratory infection: symptoms and treatment").

The first panleukopenia vaccination is usually given at 8–9 weeks of age, followed by further doses every 2–4 weeks, so that the kitten receives the last one at 16 weeks of age or later—maternal antibodies can block the effect of earlier doses. A booster is given at 26 weeks of age or after a year. In adult cats, panleukopenia boosters are usually given no more often than every 3 years, and the exact schedule depends on the cat's immune status and on the epidemiological situation the cat is in.

When can I bring a new cat into a group of cats that has had panleukopenia?

Let me remind you: feline panleukopenia virus (FPV), the cause of panleukopenia, is very hard to eliminate, and it remains infectious for up to a year. To bring in a new animal safely (a dog—it may also be infectious to dogs to some extent—or a cat), we must very thoroughly disinfect all rooms, spaces and things the sick animal had contact with. If we do not have access to 4% formaldehyde or 6% sodium hypochlorite, using a UV lamp is advisable.

However hard it may be, you should burn (not throw away, as they would be a threat to the environment) all the belongings of the previous, sick cat:

• scratching posts,
• toys,
• bowls,
• beds,
• cat toys,
• and other items.

Ideally, we should wait about 1 year before bringing a new animal onto the premises, and the new animal should be brought in at least 2 weeks after its last vaccination against infectious diseases.

Summary

Unfortunately, you must remember that if you owned a sick cat, you are a source of infection for other cats and dogs for as long as a year after your pet's death. If the worst has happened, try as far as possible to avoid places where many animals gather, such as catteries, foster homes or shelters, so that you do not cause disease in other animals.

Remember: prevention is what matters most. That is why only regular deworming and vaccination of your animals guarantees that you are protecting them properly against this dangerous disease. I am confident that, having read the whole article, you now know how to protect your cat from panleukopenia, and you realize that you, too, can be the cause of infection. I hope I have managed to explain how you can recognize the signs of the disease and how it is treated.

If you would like to know more about treatment, how much treating feline distemper costs and how to care for your cat during therapy, leave a comment below the article now—I will answer all your questions.

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