Feline Distemper: CAT FANCY’s First Look

See how CAT FANCY editors took on the subject of feline distemper in the charter issue from 1965.

From the Archives of CAT FANCY: Enjoy this all-access pass to cat history from the pages of the oldest living cat magazine. This content remains in its original form and reflects the language and views of its time. Health and behavior information evolves and only the most current advice should be followed.

Excerpted from CAT FANCY magazine, Charter Issue, 1965

Feline distemper is the most explosively deadly cat disease. The fact that some of the most effective vaccines known are available against this disease should make it a rare occurrence in the well cared for a cat. Vaccination against feline distemper is relatively inexpensive, usually costing about half that of the usual canine vaccinations. Treatment is always expensive, and the chances of survival are usually poor. Heartbreak and unnecessary expense can be avoided by early vaccination of your kitten, followed by yearly “booster” vaccinations.

Vaccination may be given shortly after kittens are weaned, 7 or 8 weeks of age. Resistance to the disease is present about 7 days after completion of vaccination. Thus, if a kitten is inoculated at the earliest possible age, the possibility of exposure to feline distemper before it has built up its immunity is greatly minimized.

The very name of the disease, feline distemper, has led to a great deal of confusion.

Until 1928, when the virus causing this disease was first isolated, all highly contagious diseases of cats were called distemper. The fact that unrelated diseases in dogs and in horses are also known as distemper only serves to confuse the situation. Feline distemper, the specific virus disease of cats, as we know it today, is also known by several other names: infectious feline enteritis, or gastroenteritis; cat fever; show fever; cat plague; feline panleucopenia; and others. Feline panleucopenia is the name preferred by technical authorities, although the vaccine against it continues to be officially labeled “Feline Distemper Vaccine”

The course of this disease may be exceedingly short, particularly in kittens under 6 months of age. Death can occur in 12 to 24 hours after the first signs of illness. In neighborhood epidemics, people might think that a cat poisoner is at work. Local human eccentrics are regarded with suspicion. But it is the feline distemper virus that is doing the deadly work.

Feline distemper is a highly contagious disease, characterized by an extremely short course and a very high mortality rate. There is at first a high fever of 104 to 105 [degrees] or more, which lasts about 24 hours. It then drops to nearly normal for another 24 hours, followed by another temperature rise, which may go even higher than the first. Just before death following either temperature rise, the temperature becomes subnormal. Diarrhea and vomiting may occur later in the course of the disease. Both of these are usually characterized by a yellowish to orange color and very foul odor.

Severe dehydration will occur early in the course of feline distemper and become extreme if and when vomiting or diarrhea begin. An afflicted cat may assume a position flat on the floor on his abdomen, his head hanging over the water dish. Piteous meows or cries may be heard due to severe abdominal pain. Handling him may cause even greater cries of pain.

The incubation period of feline distemper, following exposure may vary from 2 to 10 days, and average from 5 to 7 days.

A cat well along in the incubation period, while looking and acting normally, may have virus in his blood stream. He will be shedding this virus in all body secretions and excretions wherever he goes, your back yard or anyone else’s.

Exposure to feline distemper can take place by almost any means, even from a flea which was on an infected cat. Direct contact with an infected cat is not required. Contact with something which would have been in contact with the infected cat is enough. This could be the clothing of a person who had picked up or held the cat who had, or was just coming down with, feline distemper. Thus a person could unwittingly get his shoe contaminated in his own yard, track it into his house, and expose his own cat, which in his entire lifetime had never been out of the house.

The feline distemper virus can survive for at least 3 months in a sheltered place, perhaps even longer. So do not bring a cat of any age into a contaminated place for at least 3 months. When you do, be sure that your cat or kitten has been vaccinated long enough beforehand to have built up his immunity, 7 to 14 days, depending on the type of vaccine used.

Mortality can be as high as 90% in kittens, 60% or more in older cats. In the case of severe neighborhood epidemics, where many cats have died of the disease, the feline distemper virus appears to increase in virulency (ability to infect and kill) to the extent that even cats which were vaccinated a year or more before will get sick. The mortality is not as great in these individuals, but it does point up the great value of yearly “booster” vaccination.

The entire cat family is susceptible to feline distemper including the very large cats, such as the tiger. The ocelot, margay, and jaguarondi are particularly susceptible. Outside the cat family, the raccoon is the only other species known to be susceptible, although in recent years the kinkajou and the coati mundi have become suspect. Attempts to transmit feline distemper to other species of animals have been unsuccessful.

The thing that actually happen in the body of the cat, once feline distemper infection starts, are first all a severe depression of bone marrow function which causes an almost immediate lowering of the white blood cell count. Later a lowered red cell count becomes evident, should the cat survive. This tends to correct itself once the cat has started a recovery. Other changes include severe inflammation, and even destruction, of the mucous membrane lining the intestines. This shows up by causing committing and diarrhea later in the course of the disease, if the cat lives that long. Severe dehydration occurs as the result of the high fever and becomes extreme once vomiting and diarrhea begin.

Most cats, if they are going to recover from feline distemper, begin to show signs of improvement within 3 to 5 days. A few will recover after a longer time, and some will die after apparently starting a satisfactory recovery. Treatment, obviously, should be begun as soon as any illness is noticed. Where the temperature is still very high, prompt veterinary treatment can increase the chances of survival considerably.

Discharges from the eyes or nose rarely, if ever, occur from feline distemper infections. If present, they are nearly always due to a secondary infection with bacteria or one of the respiratory virus groups, such as rhinotracheitis or pneumonitis. This is in contrast to canine distemper in which ocular and nasal discharges are fairly constant in the later stages of the disease.

Severe infections of the gastrointestinal tract can occur from other causes. The cat may act just as sick and run just as high a temperature with these other infections, although the mortality is not high when a proper treatment is given. One in particular, caused by the colon bacillus (E. Coli) can cause identical symptoms, including a greatly lowered white blood cell count. An offhand diagnosis of feline distemper in a properly vaccinated cat, which has had yearly “booster” vaccinations, may therefore be regarded with suspicion. Every time a cat is listless and runs a very high temperature does not necessarily mean that it has feline distemper. However, in unvaccinated cats, feline distemper is always highly probably, and should be strongly considered in prescribing treatment.

Recovery from feline distemper confers a solid immunity, perhaps for life. The big question is, was it really feline distemper, or was it some other less fatal infection that merely resembled it in that particular cat? In cases of doubt, it is well to vaccinate against feline distemper as soon as the cat is sufficiently recovered.

Vaccines against feline distemper are among the most effective known against any disease of any species of animal. This is in contrast to canine distemper, in which many dogs lose their immunity after a few months, or fail to build up enough in the first place. This, unfortunately, does occur in our canine friends, in spite of many years and millions of dollars spend in research on the problem.

Three different types of vaccine are presently available against feline distemper. The oldest type, a killed tissue vaccine, is given in a series of two injections, 7 to 10 days apart. This is the vaccine which is also most commonly used for “booster” vaccinations, one injection being given yearly.

The second type is similar, except that it is in a special type of oil suspension to delay absorption so that only one dose is needed. Immunity takes 10 to 14 days to develop.

The third type is the newest, and is known as Mink Enteritis Vaccine. Mink enteritis is related to feline distemper in much the same way that cowpox is related to human smallpox. Cowpox virus is used to vaccinate humans against smallpox. The difference here is that killed mink enteritis virus is used in the vaccine for cats where live cowpox virus is used for human smallpox vaccination. A person with a good “take” could give cowpox to a cow for a period of several days, but a cat vaccinated with mink enteritis vaccine could not give mink enteritis to a mink. Only a single injection is given. Immunity is said to occur after about 7 days.

Feline distemper antiserum, made from immune cats, can confer a temporary immunity) most often used in young kittens), lasting for 5 to 10 days, but should be given more exposure to obtain maximum effectiveness. It is also useful in the treatment of feline distemper, in which a much higher dosage is necessary.

Temporary immunity to feline distemper may be present in nursing kittens, but only to the extent of the mother’s immunity. This is because they acquire the antibodies against disease from the mother. Naturally, they can get no more antibodies from her than she has herself. Thus kittens from a non-immune mother would have no protection whatsoever. In problem situations, kittens may be vaccinated against feline distemper at 4 or 5 weeks, but vaccination should be repeated after 8 weeks of age. Your Doctor of Veterinary Medicine is the person most qualified to choose the type of feline distemper vaccine best suited to your locality and your own particular situation. He is also the one best qualified to examine your cat or kitten, and then administer the vaccine. Any individual that is ill, or doing poorly, may not be capable of building up a satisfactory immunity. This is true of any vaccine given to any species. Reasonably good health is necessary before any antibody-building systems can function properly.

In conclusion, feline distemper is a highly contagious disease of cats, with a very high mortality rate. Several effective vaccines are available against it. Your veterinarian can start immunization of your kitten as early as 7 or 8 weeks of age. The cost is nominal, compared to the cost of treatment, which is always expensive. Besides, there is a poor chance of survival, even with early treatment. Feline distemper vaccination is cheap and effective insurance against the loss of your kitten to this terrible killer. 

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