Thursday 14 August 2008

Feline leukemia symptoms

Kacey a FeLV cat photo by Purrs & Paws of A.R.A.S.

Feline leukemia symptoms are unspecific and masked by the symptoms of other diseases that have taken hold due to the presence of the FeLV virus.


The search term "feline leukemia symptoms" can mean two things; either people are looking for the symptoms of the cancer, leukemia or rather the symptoms of the feline leukemia virus (FeLV). I presume it is the latter. The FeLV virus can cause, in a small number of cases the cancer Leukemia (see below - persistent viremia). Because the virus causes a range of other illnesses it can be called "Feline Leukemia Virus Disease Complex" and can be shortened to:


This virus causes more cat illness (diseases) than any other virus. After injury ("trauma") it is the second most common cause of death. It is then a very significant cause of illness that is also the main cause of feline cancer and exacerbates other diseases.


Cat saliva infected with FeLV is the transmitting substance. Cat saliva is found in food bowls, water bowls, is transmitted by cat bites and one cat grooming another and by a mother to her kitten before birth as an embryo. Repeated exposure is needed to transmit the virus.

How prevalent is it?

Outdoor cats: 1-2% (not sure if this is USA or UK or elsewhere or a world average) have the virus in the blood. For multiple cat households: 20-30% of cats have the virus in the blood. I am shocked at this figure (src: Cat Owner's Home Veterinary Handbook by Drs Carlson and Giffin -this is a fine book published in 1995 so I presume that these figures relate to a time before 1995, things may have changed). Half of infected cats have antibodies that neutralize the virus.

Feline leukemia Symptoms

Signs of illness are:

--first 2-16 weeks - vague Feline leukemia symptoms, nothing specific - fever, apathy, loss of appetite and weight - vomiting - constipation (treating constipation) - diarrhea (treating diarrhea).

--thereafter according to Drs Carlson and Giffin (see above) there are three possible outcomes:

1. The cat cures her/himself. The cat produces antibodies that kill off the disease. The virus remains in the blood for about 12 weeks. This is called "transient viremia". "Viremia" means a virus in the blood. These cats cannot transmit the disease. So in these cats the feline leukemia symptoms may be as described above.

2. The cat cannot defeat the virus and it remains in the blood for over 12 weeks ("persistent viremia"). The presence of the virus leaves the cat susceptible to other diseases by suppressing the cat's immune system. These other diseases kill the cat. Half die within six months and 80% die within 3.5 years. These are part of the group of adoptable FeLV cats (this link goes to another similar page written much earlier that focuses more the adoption of FeLV cats). My thought: the fact that the FeLV virus leads the door open for other fatal diseases would mean that Feline leukemia symptoms are masked by the other disease. This would "muddy the water" of a diagnosis. The FeLV virus would be an underlying cause to be isolated in the diagnostic process. The symptoms presented would be those of the new illness. There are 2 tests to detect the presence of FeLV in a cat.

A small number of cats in this group may develop cancer caused by the virus. There will, then, be symptoms of cancer. The most common is Lymphosarcoma, an abnormal mass of tissue present in the lymph nodes or bone marrow for example. Another cancer caused by this virus is Leukemia, cancer of the blood, a rapid uncontrolled growth of white blood cells. Once again the symptoms of leukemia are sometimes unspecific and can include: malaise (feeling ill), fatigue, weakness and weight loss.

3. The cat partially defeats the virus ("latent infection"). The virus remains in the cat's bone marrow and T-cell lymphocytes. The disease is therefore suppressed. These are adoptable FeLV cats as well. The disease can be activated at moments of stress or because of the presence of another illness. These illness will present their own symptoms but the underlying cause will be the FeLV virus.

The virus can also cause anemia and "spontaneous bleeding". Kittens born with the disease may suffer from fading kitten syndrome (a range of illness preventing the kitten from thriving).

Feline leukemia symptoms to Cat Health Problems


  1. Cat Owner's Home Veterinary Handbook by Drs Carlson and Giffin
  4. Wikipedia for definitions


  1. This is a great article. Thanks for including the prevalence % and the timeline for the virus. This blog is setup so well I couldn't even tell it was on Blogger. Keep up the great work.

  2. All types of cancer is painful, so be it animal, since they also feel pain like humans, unlike us as we have painkillers hydrocodone, vicodin, norco findrxonline which he said, are used to solve pain causing diseases such as cancer, leukemia, Parkinson's, while in animals is still inaccurate to define what is best.

  3. Just a cat lover in texas. Over the past 5 years are more I have watched and studied my cats I have had as many as 20 cats at one time. At one point I had a calico stray come to my house, very healthy kitten/cat.Until a siamese mated with her. She contracted the leukemia from this male cat. She started sleeping alot, not being very active at all. every time she had a litter of kittens some would be sick one or two would survive but would grow up to be sickly. Some of her chilren would have babies then die. when her final year came to,I brought inside to tend to her.In her last 6 months of life. I took her to the vet. He then proceded to tell me that siamese are carriers of this disease.It"s alot like Aides or Hep C is to us. It can be transmitted by sex between two cats. Cat birth,Or nursing their babies,saliva. These are based on my own observations,and my research, and what my vet enlightened me on. Once your cat is diagnosed with the leukimia, they can live a very happy life as a house cat.I also had some female cats that were healthy until they had babies then the leukimia kicked in. Once the male has transmitted the disease to the female then she becomes the primary carrier of this disease. Once I had discovered that my cat had this disease I was afraid to get her fixed because it lowers their immune system and healing process. Hope this helps other cat lovers out there. bonmom

  4. The virus must be transmitted from cat to cat. It is found in cat's that have not been vaccinated, in cats where the vaccination has not taken hold such as kittens that were vaccinated too early, outdoor cats and adopted cats.

  5. Symptoms of FeLV in pregnant cats are identical to the previous. When a cat shows symptoms of feline leukemia, there are a couple of tests that the vet can run for a positive diagnosis.

  6. My cat Reckless is 6yrs, he was active and healthy 1 month ago with a good weight and playful and four weeks he has gone down to 8 lbs, his spins and ribs are felt, he is not eating, he is 10% dehydrated, his glucose is 14.07, elevated, urea, 24.8, elevated, TP is 94, elevated, glob is 55, elevated, vet noticed hard fecal balls in colon, generalizd skin lesions, mild tartar, urine stick usg >1.050 protien 2+...when I took him to the vet today it looked to me like he was on death's door...he is such a lovely boy and only 6...what could be going on...he was in my mothers care for 2 months...multiple cat household...but this cat is indoor, others are outdoor????


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