Feline leukemia is also known as cat leukemia, with “leukemia” being spelled as “leukaemia” in some parts of the world. This is a serious and life threatening viral disease, and vaccinating young cats, in particular, is a sensible way of protecting vulnerable animals from infection.
What Is Feline Leukemia?
Feline leukemia is one of the most common infectious diseases of cats in the world. The disease is caused by the Feline Leukemia Virus (FeLV).
The virus has a profound effect on the immune system, the bone marrow and blood cells of the cat, and there are up to six stages of infection: infected cats can be asymptomatic carriers for many years, but the clinical signs and the long term prognosis is variable, depending on a number of factors.
Clinical signs may include weight loss, gingivitis (inflamed gums), stomatitis (inflammation of the lining of the oral cavity), and a range of other possibilities. While some cats can live a healthy life, with a normal lifespan, other cats can have a mortality rate of around 50% in 2 years and 80% in 3 years.
How Does Feline Leukemia Spread From Cat To Cat?
FeLV transmission generally takes place during close social contact between infected and uninfected, unvaccinated cats. The virus is shed principally in saliva, but it is also present in blood, urine, faeces, tears and nasal secretions, as well as in the milk of infected mothers.
The virus is primarily passed on by oral or nasal exposure to viral particles, but it can also be spread via bite wounds. Common methods of transmission include food and water dishes, shared litterboxes, and mutual grooming between cats that are affectionate to one another.
What Is The Cat Leukemia Vaccine?
Feline Leukemia (FeLV) vaccines are licensed to stimulate immunity to FeLV in cats. Various formulations are available, including inactivated, whole virus vaccines, recombinant subunit vaccines; and genetically-engineered, subunit recombinant vaccines linked with a canary pox vector virus.
Should Your Cat Get The Feline Leukemia Vaccine?
Feline Leukemia vaccine is classified as a non-core vaccine under the World Small Animal Veterinary Association (WSAVA) and American Association of Feline Practitioners feline vaccination guidelines, meaning that the need for vaccination is dictated by geographical location, lifestyle and exposure risk.
Indoor cats that never encounter other cats should not be at risk of picking up Feline Leukemia, so vaccination may not be necessary. However cats that roam outdoors, coming into contact with other cats, are likely to be at risk, so vaccination may be recommended. Every cat owner should discuss this topic with their own veterinarian, making a decision based on the individual risk of the cat.
Also Read: Should You Let Your Cats Outside?
It’s important to distinguish FeLV from another retrovirus infection, Feline Immunodeficiency Virus (FIV), and from Feline Infectious Peritonitis (FIP), a type of coronavirus infection. These disease names may sound similar to a cat owner, yet they are entirely different diseases, and will be discussed in different articles.
When Should Your Cat Get A Feline Leukemia Vaccine?
Kittens should be given an initial vaccine at 8 – 12 weeks of age, depending on the specific vaccine product; and a second dose is normally given 3-4 weeks later. An annual booster vaccination is generally recommended but should be discussed with your vet annually.
Also Read: Cat Vaccination Schedule
These vaccinations are often combined with routine feline vaccines known as FVRCP against the common respiratory infections often called “cat flu” (feline viral rhinotracheitis and feline calicivirus) and feline panleukopenia (feline distemper).
The vaccine will not protect cats that are already infected with FeLV, so FeLV testing (usually using an in-house elisa blood test or an IFA test) prior to vaccine administration is recommended.
Only healthy cats and FeLV negative cats should be vaccinated.
How Much Does The Feline Leukemia Vaccine Cost?
The cost depends on your location and your choice of DVM veterinarian: you should phone around your local area to discover the range of prices on the market place. In general, the fee represents a combination of a veterinary clinical examination of your pet (to make sure that they are healthy enough to vaccinate) as well as the cost of the vaccine itself. The Avg. cost for the Vaccine in the US is around $20-$25.
Cat Leukemia Vaccine Side Effects
Side effects of FeLV vaccination are rare and usually very minor, such as transient episodes of dullness, with mild pyrexia. Occasionally there may be minor swelling and discomfort at the injection site.
Historically, injection site sarcoma (a type of cancer) was linked with FeLV vaccination, but more recent studies have shown that adjuvant-containing (killed) rabies and FeLV vaccines have a ten times higher risk of tumor formation compared to more recently developed recombinant rabies and FeLV vaccines.
It’s important to note that all recombinant and modified live virus vaccines now sold in the US and Canada are adjuvant-free.
As with any injected product, exceptionally rarely, a severe anaphylactic allergic reaction can occur after FeLV vaccination. As a veterinarian qualified for over thirty years, I have never witnessed this after a cat vaccination.
Frequently Asked Questions
Is the feline leukemia vaccine necessary?
Feline leukemia virus infection (FeLV infection) cannot be passed on indirectly in the same way as other viruses: close contact with other cats is needed for viral transmission. For this reason, FeLV is regarded as a non-core vaccine by authorities such as WSAVA and the American Association of Feline Practitioners. However, to be safe, FeLV vaccination is highly recommended for all kittens in the United States under the AAFP vaccination guidelines, while booster inoculations are only recommended in adult cats considered to be at high risk of exposure such as outdoor cats, or a new cat entering a cat household that includes FeLV positive cats.
How often should cats be vaccinated for feline leukemia?
Duration of immunity depends on the precise vaccine used and the immune response of your cat: this can vary from 12 months to two or three years. Revaccination (using a single dose of the vaccine) also depends on other factors such as the risk of your cat to exposure to the virus. The topic should be discussed with your own veterinarian at your cat’s annual veterinary check as part of their routine health care.
Can a cat get feline leukemia after being vaccinated?
While it’s regarded as being effective, FeLV vaccination does not protect 100% of cats from becoming infected. The only certain way to protect cats from FeLV is to prevent their exposure to FeLV-infected cats. This means keeping cats indoors, or in an outdoor enclosure, and it means that all cats should be tested for FeLV infection prior to introducing them into a home
My husband and I presently have a feral mama cat who tested positive for FeLV when we brought her into our vet for TNR five weeks ago. Now we are prohibited from releasing her. She came with five kittens, three which also tested positive. Our vet instructed us to keep the mama separated from her babies (she’s presently in our remodeled bigger bathroom), just in case they can slough off the disease. We’ve also segregated the negatives from the positives in the back part of our house. They have had their second shot as of this past Monday. We were told it will take two more weeks for the second vaccine to be fully activated.
My question is this: can we reintroduce the vaccinated kittens to their litter mates? My vet would rather we err on the side of caution (and I partly agree!) and just keep them separated forever, but that’s not going to be very easy to do long term. I’ve joined a support group for owners of FeLV positive cats and about 90% of those who responded to this question tell me that they have a mixed household without any issues. However, I want to do what’s right, so our only option would be to rehome the negative kitties. Unfortunately, I’ve not found anyone who wants a kitten.
Thanks for considering a reply. 😀
I’m sorry to hear about this complex situation and congratulations for taking such responsibility in dealing with it all so thoughtfully.
I would tend to support your vet’s view: no vaccine is ever 100% and if either of those kittens turned out positive, it would be very grave for them. So the best answer, I think, would be to continue to seek a home for them, where they remain isolated from a confirmed infectious source of FeLV.
It’s all about risks though, and you may yourself decide to take the risk of mixing them, in the hope that they are, indeed, strongly protected against future protection.
There is no 100% definite right or wrong answer, just different levels of risk that you may or may not wish to take.
I hope this helps
Thank-you for sharing your thoughts and expertise. It is definitely a conundrum for us, especially since we’ve become quite partial to the two negatives.
I have a feral cat sanctuary on Maui with about 250 cats. I started immunizations with the combined Nobivac Feline 1-HCPCh+FeLV a year ago, with most cats I was able to secure and vaccinate. I gave most a second booster 4-8 weeks later.
It would be difficulty to vaccinate every cat because they are feral and live on 7 1/2 acres. I am not able to afford to do FIV/FELV testing on all admissions. What would your recommendations be for best practice to do boosters, how often and do they need a second booster each time?
Thank you for your time,
Surf Cat Ranch
Because every cat deserves a home.
The issue of booster vaccinations is complex. The best answer is to discuss this one-to-one with your own veterinarian who understands the disease risks in your locality.
The World Small Animal Veterinary Association has written guidelines which most vets refer to https://wsava.org/global-guidelines/vaccination-guidelines/
My own view is that in general:
1) The primary course of FeLV is the sacrosanct one because younger cats are most vulnerable: by the age of 1 year of age, cats have a natural 80% immunity against the disease. So for a situation like your own, I would not place huge importance on boosters after the primary course.
2) The primary vaccine against Feline Enteritis provides protection for many years, possibly even for life, so I would not worry about this either.
3) Protection against herpes virus and calicivirus is less easy to be sure about and booster vaccines depend on perceived risk. A cat doing a lot of socialising, going to shows, boarding kennels etc should have once yearly boosters whereas a cat living mostly in its own space, not so many social contacts, every 2 – 3 years is enough. Not sure where your cats fit on this, but my sense would be to give all cats a primary course, then perhaps every 3 – 4 years, trap every cat in the place and give them all a booster at that time.
But do talk with your own vet: opinions differ.