Feline Leukemia Virus and Your Outdoor Cat

Now that it is summer, you may have a cat that goes outdoors more often. In a previous article we discussed parasites which can affect dogs and cats, and today we will discuss feline leukemia. Feline Leukemia (FeLV) is one of the most common contagious diseases among cats, and something to be aware of with outdoor cats. Because feline leukemia is highly contagious, identifying it early on is very important.

FeLV, is a retrovirus. The retrovirus’ are a group of virus named because of a particular way they behave within infected cells. 
 FeLV-infected cats are found worldwide, but the prevalence of infection varies greatly depending on their age, health, environment, and lifestyle. The prevalence in Canada is 2-3 % but may even be as high as 15% in sick cats.

Transmission occurs from cat to cat contact. Cats already infected with the feline leukemia virus are the source of infections. The virus is shed in high amounts in saliva, urine, feces and milk. Outdoors cats may become infected from a bite wound or during grooming. An infected mother can transfer feline leukemia to her kittens either before they are born or when they are nursing. The greatest risks of infection are with cats who are allowed outdoors unsupervised and kittens born to infected mothers.

Kittens are much more susceptible to infection than adult cats (100% of kittens exposed to sufficient virus vs only 30% of adults become infected). Because kittens are so susceptible, your veterinarian will often recommend screening for this contagious disease at one of the first visits or along with other tests if your cat is ill. Infection can be diagnosed using a blood test.

It is common for cats to show no signs of disease at all during the early stages of infection. However, over weeks, months or even years an infected cat may have recurrent infections and/or their health may progressively decline. FeLV affects a cat’s ability to protect itself against other infections. The same bacteria, viruses or parasites that are found in the everyday environment which do not affect healthy cats can cause illness in cats with a weakened immune system. Feline leukemia virus is one of the most common causes of cancer in cats, and is also a cause of blood disorders.

Managing a cat who has been diagnosed with feline leukemia consists of feeding a nutritionally complete and balanced diet, regular wellness visits with your veterinarian. Monitor your cat’s health closely for change. Alerting your veterinarian at the first sign of change is the best way to control secondary infections and address health concerns as soon as possible.

The only sure way to protect cats is to prevent their exposure to FeLV-infected cats. Keeping cats indoors, away from potentially infected cats that may bite them. If you do allow your cats outdoor access, providing supervision or placing them in a secure enclosure can prevent wandering and fighting. Consider FeLV vaccination of uninfected cats and discuss the advantages and disadvantages of vaccination with your veterinarian. When adopting a new cat, ensure only infection-free cats are introduced into households with uninfected cats.