Feline Leukemia Virus
Your Cat Could be at Risk

Feline leukemia virus is also referred to a FeLV. FeLV is a retrovirus that affects domestic cats. The FeLV retrovirus is an RNA virus which means that it needs to enter the host's (cat) cells and use the host DNA to replicate.

It is generally regarded as one the most common, lethal and contagious illnesses affecting our feline companions.

It is particularly virulent in kittens. The cat leukemia virus causes certain carcinomas (cancers)and impairs the function of the immune system.

In short, FeLV is an immunosuppressive viral infection.

feline leukemia virus vs leukemia

There may be some confusion with regards to leukemia and feline leukemia virus and we believe it's important to clarify and distinguish between the two.

Leukemia is the name given to a number of cancers that affect the infection-fighting white blood cells and where there is an abnormal over production of white blood cells.

Blood cells are produced in the center spongy part of the bone called the marrow. When white blood cells multiply in an abnormal and uncontrolled way, these immature cells take over, literally crowding the bone marrow thereby preventing it from producing healthy blood cells and causing a shortage of red blood cells.

These immature or malignant cells then enter the circulatory system (blood stream) and spread to other vital organs of the cat's body.

Ultimately, this results in a number of conditions:

  • There is an increased tendency to bleed as there are few if any platelets to assist with the clotting of blood;
  • anemia results due to a lack of red blood cells and therefore decreased iron and hemoglobin and
  • finally a weakened immune system causing serious infections due to a lack of mature white blood cells to fight infection.

The cause of leukemia in cats is unknown.  It is thought that genetics and environmental factors play a part.

The Feline Leukemia Virus known as FeLV, is one of the major contributors of cat leukemia.

Sadly, the cat leukemia virus is not only responsible for causing leukemia in cats, it is also responsible for causing fatal tumors called lymphosarcomas, anemia and many other diseases that result from a compromised (weakened) immune system.

transmission of feline leukemia virus

How is FeLV transmitted? The FeLV virus is a stable virus which needs a host to mutate. It is also a relatively 'frail' virus which does not survive for long once it is outside of the cat's body.

Experts disagree on how long it lives outside the body. Some believe that the virus lives for a few minutes outside the body, others believe that it may last for up to 48 hours in damp conditions and 2 hours in dry conditions.

Generally, the most common mode of spread is via the saliva of infected cats.

In multi-cat households or catteries the feline leukemia virus is transmitted via direct contact during mutual grooming or through a bite during a cat fight.

It stands to reason that the sharing of cat food and cat water bowls could also provide a vehicle for transmission.

Some experts believe that this mode of spread is unlikely, but we err on the side of caution given that it can't be confirmed how long the virus survives outside the body.

The virus is also present in other bodily fluids like blood, nasal secretions (respiratory mucus), feces, urine and cat's milk.

If blood presents a potential mode of spread, contaminated veterinary instruments and needles will be discarded or sterilized (via heat or disinfectant) prior to re-use.

The queen who is FeLV positive or viraemic (i.e. virus circulating in the blood) will pass on the virus in two ways - via transplacental transmission i.e. when the kittens are in utero and also via milk when nursing her kittens.

Kittens are also at risk after birth via saliva during grooming.

Shared litter boxes may present a mode of spread if cats come into direct contact with contaminated stools or urine.

cats at risk

FeLV is a contagious disease and as such all cats are at risk unless of course they have been vaccinated and live in a healthy indoor environment.

  • Kittens and young cats are at greatest risk.
  • Cats that live in large, densely populated communities and in close proximity to each other are at greater risk than cats living in single-cat households.
  • Outdoor cats are also at risk if they are allowed to roam the neighborhood instead of being confined to an escape-proof garden.

Having said all this, feline leukemia virus can raise its ugly head at any time, it does not discriminate between the age of the cat, the cat breed type or the sex of the cat.

incubation period

FAQ:  How long after exposure to the cat leukemia virus will my cat get sick?

Well the answer is it varies.

The virus can lie dormant in the host's cell DNA for several years before any signs or symptoms appear. The cat may then for some reason start 'shedding' the virus and it is then that the cat will start presenting with signs of illness.

In other cases, the kitten or cat will become gravely ill within a few weeks of exposure to the virus.

how common is cat leukemia virus

FeLV was discovered in 1964 and has worldwide distribution, but does have geographical variations.

This virus is considered to be a significant contributor of cat diseases in felines.

It is also believed that 1 in 20 healthy-looking cats may in fact be infected with this virus.

Experts also believe that 7 in 10 cats will at some stage come into contact with the leukemia virus and 3 in 10 cats are likely to die from the disease.

Related Feline Leukemia Information:

Feline Leukemia Symptoms

Feline Leukemia

Top of Feline Leukemia Virus

Return to Feline Diseases



search our site

please like us

share our site

recommend on google

favorite pages

Cat Care

Cat Insurance

Dry Cat Food

Cat Nail Care

How Long Do Cats Live?

Cat Not Using Litter Box?