Cat Leukemia. a.k.a. Feline Leukemia, FeLV

 Cat leukemia is a highly infectious viral disease first detected in the mid sixties.

It is estimated that over ten percent of feral cats are infected with the virus.

Thankfully the infection rate among domestic cats seems to be a lot lower, probably around three percent.

However this virus is very worrisome for cat owners as, apart from being very infectious, there is no known cure at this present time.

The feline leukemia virus is a retrovirus.

Simply put, a retrovirus does not act like a normal virus, it invades the white blood cells and, instead of destroying them, implants a replica of its own genesiological material.

This action suppresses the animal's immune system. 

Therefore the poor cat is unable to fight off infections and bacteria in a way that an uninfected cat would.

How is Cat Leukemia Transmitted From Cat to Cat?

The leukemia virus only survives outside of the infected cat's body for a short time, so transmission is usually by direct contact with an infected cat.

The virus is found in saliva, nasal fluids, other secretions, urine and feces.

Infection can occur through bite and scratch wounds from fighting, and scratches from mutual grooming.

A mother cat infected with the virus will pass it to her kittens, either when they are in the womb or when they are nursing.

An infected cat sharing litter trays or food bowls with uninfected cats can pass on the virus, but this is less common as the cat leukemia virus does not survive long outside the infected cat.

The Symptoms of Cat Leukemia

Often, during the early phase of infection, the cat will show few if any symptoms. As time goes on though, the cat's health will deteriorate and symptoms will be apparent.

cat and vetSadly there is no cure for FeLV. Treatment is aimed at keeping the cat as healthy as possible by managing the progression of related diseases, which may be many.

The cat's health may appear to improve at times only for it to regress later with a general deterioration over time.

Symptoms of cat leukemia may include, but are not limited to:

Weight loss, poor appetite, fever, pale gums, inflamed gums, mouth sores, eye conditions, excessive thirst, excessive urination, breathing difficulties, skin infections, poor coat condition, constant diarrhea, constipation, seizures, abortion of kittens.

Any of the above signs could be a symptom of many conditions or diseases, not only FeLV. But all are an indication that something is wrong and that it is very likely your cat urgently needs the attention of a vet.

Learn more about feline leukemia symptoms.

Can Feline Leukemia Be Prevented

The only way to be certain that a cat does not become infected with FeLV is to ensure that the cat is kept indoors at all times.

Also the cat must only come into contact with cats that have been tested and found to be free of the cat leukemia virus.

If the cat does go outside then neutering will slightly improve their chances of remaining free of the virus.

Neutered males are less inclined to fight than are whole Tom cats, so there is less chance of them being infected by bites and scratches. Females that are spayed are less likely to be infected through sex.

Treatment and Management of a FeLV Infected Cat

Sadly there is no cure for FeLV. Treatment is aimed at keeping the cat as healthy as possible by managing the progression of related diseases which may be many.

Treatment will need to be tailored to the specific needs of the cat who will benefit from good nutrition and the least stress as possible.

Antibiotics may be included in the treatment along with other preparations.

Any FeLV associated cancers will need to be treated with chemotherapy.

If being treated as an outpatient, there will be regularly scheduled visits to the veterinarian where the cat's condition can be monitored and changes made to treatment if necessary.

The cat's health should also be monitored in the home and the veterinarian notified of any changes immediately.

To prevent further spread of the virus, any cat infected with cat leukemia will need to be kept indoors at all times, absolutely separate from any other cats.

Can Humans Get Infected With Cat Leukemia?

No. Many studies have been made that have shown that the feline leukemia virus is not passed to other animals or human beings. It can only be transmitted from an infected cat to other cats.

However, cats infected with FeLV may be carrying other viral diseases so it is advised that humans at greatest risk - people with AIDS, those undergoing chemotherapy, pregnant women, very young children and the elderly, do not have contact with infected cats.

Vaccination and Testing for FeLV

A test will be made before vaccination for FeLV. If the test proves positive the vaccination will not be given, there is no benefit to vaccinating a cat that already has the virus.

black and white cat face

Testing for feline leukemia is somewhat complicated and can sometimes be inaccurate.

A blood test can be carried out in the veterinarian's office. But often a different blood test will also be necessary and this one has to be performed in a laboratory.

Often, when the result of the tests is known, it will be deemed necessary to repeat them at a later date. This is the best way of ensuring the accuracy of the results.

Should All Cats Be Vaccinated for Feline Leukemia Virus?

The answer is – all uninfected cats should be vaccinated against FeLV.

Many people may reason that a strictly indoor only cat, that does not come into contact with any cats that go outdoors, has no need to be vaccinated.

Indeed, the chances of such a feline getting cat leukemia are very slight. But the following needs to kept in mind.

Indoor only cats have the habit of escaping.

Cats are curious about the outside world and no matter how careful the human companion is, cats often seize any opportunity to escape and investigate.

The cat may be a solitary cat at the present, however at some point the human may bring home another cat, or kitten, that was just irresistible. The human may forget that the original cat has not had the vaccine, if the new feline is infected then tragedy can result.

It is always better to be safe rather than sorry, all uninfected cats should be vaccinated against feline leukemia virus.

Is There Any Risk of Side Effects With the FeLV Vaccine?

Yes, there is a very small risk.

The less serious side effects of vaccination can be - temporary lethargy, fever, localized swelling or a harmless lump.

A much more serious side effect can be the formation of sarcomas which are cancerous tumors. Sarcomas originate at the site of the vaccination and spread into neighboring tissue, cartilage, muscle or bone. Sarcomas can be fatal.

It must be emphasized that the risk to the feline from being vaccinated against cat leukemia virus is very small. The chances of a cat developing vaccination related sarcomas are very slight indeed.

Having a cat vaccinated equals a very small risk. Not having a cat vaccinated equals a very big risk.

How Long Do Cats With FeLV Live?

As stated above, there is no cure for cat leukemia. A FeLV positive cat will eventually pass on.

There are different strains of the virus and how the disease impacts the feline will vary from one cat to another, some infected cats are able, with proper care, to live for some time.

This page was not written by a veterinarian. If you are concerned that your cat may have cat leukemia you should urgently consult a vet. 

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