Noncore Vaccinations for Cats
The veterinary community has divided vaccines into two main categories, with a smaller third
category. Core vaccines are vaccines that every cat should have at some time
in his life. Noncore vaccines are vaccines that only some cats need, depending
on factors such as geographic location and lifestyle. Other vaccines are also
available but are generally not recommended for any cats.
Feline Leukemia Virus (Noncore)
The development of a vaccine against retroviral infection is a long-awaited
achievement in veterinary medicine. However, this vaccine is not 100 percent
effective. It is possible that some cats vaccinated for FeLV may still become
This vaccine is noncore because of its incomplete effectiveness and because
indoor cats who have been tested before coming home should have minimal risk of
acquiring FeLV and therefore should not need this vaccine. Kittens born to
immune queens acquire protective antibodies in the colostrum of the queen. This
protection begins to disappear at 6 to 12 weeks of age, after which kittens are
Cats with access to the outdoors or who roam free may need this vaccine.
However, since kittens are most susceptible to FeLV and may escape, some
veterinarians recommend vaccinating kittens and giving a first booster at 1
year. If the cat is then firmly established as an indoor-only cat, no more
boosters are needed.
Testing for FeLV is recommended before vaccination. Vaccination is not
effective if the cat is positive and already infected. If the ELISA test is
negative, vaccinate kittens at 8 to 12 weeks of age and again at 14 or 16
weeks. The first booster is given one year later.
To be effective, a full course of vaccination must be administered. This
involves two vaccinations two to three weeks apart, a booster a year later, and
then annual boosters, if needed.
Vaccines available include injectable adjuvanted killed virus, nonadjuvanted
recombinant for transdermal use, and, in Europe, a nonadjuvanted recombinant
for subcutaneous injection. According to recommendations of the
Vaccine-Associated Sarcoma Task Force, FeLV vaccines are administered
subcutaneously as distally as possible in the left rear limb.