Feline leukemia vaccine: which cats need it and how often
Updated July 29, 2026·4 minper AAFPAnswer — in the first paragraph ↓
CAT · LEUKEMIA SHOT
The feline leukemia shot is recommended for every kitten in the first year, whether or not the cat will ever go outdoors. Adults get it by risk only: outdoor access, a multi-cat home, contact with an infected cat. The course is 2 doses 3–4 weeks apart, a booster at 12 months, then every 2–3 years.
01Which cats need it, and how often
Cat
Is the shot needed
How often
Kitten under a year
yes, every kitten
2 doses, then a booster at 12 months
Adult with outdoor access
yes
every 2–3 years while the risk lasts
Adult in a multi-cat home
yes
every 2–3 years
Adult indoor cat living alone
usually not
not required
Feline leukemia is a contagious viral disease that wears down the immune system. It spreads through close contact between cats, which is why the risk sits with cats that go outdoors, live in a multi-cat home or meet a cat known to be infected. In 2020 the American Association of Feline Practitioners (AAFP) put this shot on the list recommended for every kitten in the first year. Adults are handled differently: the shot continues only while the risk does. How it fits the rest of the schedule is in adult cat vaccinations.
02A blood test comes before the first dose
Before the first shot the cat is tested for leukemia and immunodeficiency. The reasoning is simple: a cat that is already infected gains nothing from the vaccine, which only protects healthy cats. The test runs in the clinic from a drop of blood and the result is usually ready during the same visit. If it comes back positive the shot is not given, and the follow-up plan is discussed with the vet.
03Which vaccine, and where it goes
Cats are given the recombinant vaccine with no adjuvant — the additive that boosts the immune response. The reason is a rare but serious tumour that can develop at a feline injection site. For the same reason the shot goes as low down a limb as possible rather than between the shoulder blades: leukemia into the left hind leg. The first dose can be given from 8 weeks, often in the same visit as the combination shot, which is allowed.
Platera tells you when the next dose is due
A schedule for every feline vaccine and an early nudge.
Platera9:00 AM
Mia’s booster shot is tomorrow — clinic at 12:00
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04Frequently asked
How often is the feline leukemia shot repeated?
After the two kitten doses the first booster follows at about 12 months. An adult cat then repeats it every 2–3 years, and only while the risk lasts: outdoor access, other cats in the home, or a housemate cat with leukemia. If the lifestyle changes and the risk is gone, the shot does not have to continue.
Does an indoor cat need the leukemia vaccine?
An adult cat that lives alone and never goes outside usually skips it. Kittens in the first year are a different case: the shot is recommended for all of them, whatever the lifestyle. If a second cat joins the household or the cat starts going outdoors, it is worth revisiting the question with your vet.
How old must a kitten be for the leukemia shot?
The first dose can be given from 8 weeks and the second 3–4 weeks later. Both can share a visit with the other shots due at that age: the American Association of Feline Practitioners allows all indicated vaccines in a single appointment. The injections go into different legs.
Why test first if the cat looks healthy?
Leukemia can stay silent for a long time while the cat already carries the virus. The vaccine will not help such a cat, so it is only given after a negative result. The result also changes the plan: an infected cat needs a different monitoring routine and care around contact with other cats.
CAT · LEUKEMIA SHOT
