Mandatory vaccinations for cats

Veterinarians have divided vaccinations into two major categories, plus a smaller third category. Essential vaccinations are those that every cat needs at some point in its life. Optional vaccinations are those that only some cats need, depending on factors such as geographic location and lifestyle. Other vaccinations are also available, but are not generally recommended for cats.

Panleukopenia (mandatory vaccination)

The first vaccination against panleukopenia (feline panleukopenia virus) should be given at 6 to 8 weeks of age, before the kitten goes to a new home where there may be other cats. If the kitten is particularly at risk in an area where the disease is occurring, the vaccination may be given at 6 weeks of age and then every three to four weeks until the kitten is 16 weeks old. Discuss this with your veterinarian.

After the initial series of kitten vaccinations, a booster injection at 1 to 2 years of age may be sufficient for cats that socialize with other cats, as exposure to the disease enhances immunity. A booster injection is recommended one year later, and then no more frequently than every three years.

There are two types of injectable vaccines available. The first is a killed virus, the second is a modified live strain. A nasal vaccine is also available. The modified live virus vaccine is not recommended for pregnant cats or kittens under 4 weeks of age. Killed virus vaccines may be more appropriate in disease-free populations because there is no risk of reversal of virulence.

The panleukopenia vaccine is often combined with vaccinations against a complex of viral respiratory diseases of cats and is given as a single injection.

Feline viral respiratory disease complex (mandatory vaccination)

Your veterinarian may recommend an injectable vaccine containing strains of feline herpesvirus (FHV) and feline calicivirus. These are usually combined with a panleukopenia vaccine and given at least twice as a single injection, with the final dose not earlier than 16 weeks of age. Kittens can be vaccinated as early as 6 weeks of age.

Young and adult cats should receive two initial doses, given three to four weeks apart. For both kittens and adult cats, a booster injection is recommended after one year and then every three years.

Although vaccines against viral respiratory diseases are highly effective, they do not prevent all cases of the disease. A cat may be exposed to individual strains of the virus that the vaccine does not protect against, or the infection may be so severe that it outweighs protection. If this occurs, the disease is usually milder than in an unvaccinated cat. Vaccination does not prevent carrier status in cats that do become infected.

Respiratory virus vaccines are available as modified live virus, killed virus, and modified live virus nasal drops. Sneezing and nasal discharge may occur when the vaccine is instilled into the nose. The killed virus vaccine is preferred for pregnant cats and disease-free groups because there is no risk of reversal of virulence.

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Virulent systemic calicivirus disease of cats

A new vaccine, CaliciVax, has recently been introduced to combat virulent feline systemic calicivirus disease. It is an adjuvanted vaccine made from killed virus. CaliciVax contains a virulent feline systemic calicivirus strain as well as an older strain of feline calicivirus. It is intended for use in healthy cats at 8 to 10 weeks of age, with a booster dose three to four weeks later and annual boosters. However, the risk of using an adjuvanted vaccine may not be worth it unless virulent feline systemic calicivirus has been confirmed in your area.

This vaccine was introduced in 2007, after the most recent vaccination recommendations of the American Association of Feline Practitioners were issued. Its ultimate effectiveness will only be confirmed after widespread long-term use.

Rabies (mandatory vaccination)

States and cities have requirements for rabies vaccination. All rabies vaccinations must be given by a veterinarian, and in many states this is the law. Any cat being transported across state lines must have a current rabies vaccination and a certificate showing that it has been vaccinated.

There are three types of rabies vaccines available. These include a recombinant vaccine, a non-adjuvanted canarypox vector vaccine, and an adjuvanted killed-virus vaccine. All are given by injection. In general, it is recommended that kittens receive one dose of either a recombinant rabies vaccine or a killed-virus vaccine at 8 to 12 weeks of age, depending on the vaccine used. Adult cats with no known vaccination history should also receive one dose of a recombinant rabies vaccine or a killed-virus vaccine. With recombinant vaccines, annual boosters are recommended. With killed-virus rabies vaccines, a booster dose is required one year later and then every three years using a vaccine approved for every three years.

Vaccine-associated sarcoma in cats

Sarcoma is a cancer of the connective and soft tissue. Sarcoma is not a new form of cancer in cats. But in 1991, veterinarians began noticing an increased number of sarcomas occurring at sites where vaccines were commonly injected. Subsequently, a link was established between vaccine administration and sarcoma development. Feline leukemia virus and rabies vaccines were associated with sarcoma development more often than other vaccines. Both subcutaneous and intramuscular injection sites were affected. Other non-vaccination injections may also be involved.

The increase in sarcoma incidence roughly coincided with the switch from modified live virus rabies vaccines to adjuvanted killed virus vaccines. Adjuvanted vaccines (aluminum adjuvants) for feline leukemia virus were introduced around the same time. Adjuvants are added to vaccines to enhance the immune response, especially killed virus vaccines. Adjuvants in general and aluminum in particular were thought to be the cause. However, researchers are no longer certain that this is the case. These vaccines are thought to cause inflammation at the injection site, which has been linked in some cases to the development of sarcoma, but the exact link has not been proven.

Despite this, vaccine manufacturers are developing recombinant vaccines that still use excipients and cause less inflammation at the injection site. Many modified live virus vaccines are available for other viral diseases, and some do not contain excipients. New vaccination guidelines attempt to minimize the number of injections a cat receives in its lifetime and recommend where to inject.

It is important to remember that vaccine-associated sarcoma is a very rare form of cancer. The incidence ranges from 1 in 1,000 to 1 in 10,000. The wide range is likely due to a genetic predisposition to the disease in certain cats and cat families. For example, in some geographic areas the disease occurs more frequently.

This type of cancer can appear months or even years after vaccination. Although many cats develop a small lump after vaccination, it should go away within a month. If it doesn't, take your cat to the vet.

Because much remains unknown, the Feline Vaccine-Associated Sarcoma Task Force was formed by the American Association of Feline Practitioners, the American Veterinary Hospital Association, the American Veterinary Medical Association, and the Animal Cancer Society. The group is working to determine the true extent of the problem, the cause, and the most effective treatment for vaccine-associated sarcoma.

Treatment

It is an aggressive cancer that spreads in and between muscle layers, making it very difficult to remove all the cancer cells surgically. Surgery and radiation therapy before or after surgery appears to be the most successful treatment plan, but relapse occurs in most cases.