but I will endeavor to give some guidelines that will assist you in making a balanced decision regarding your feline companions.
There are four criteria that are at the center of any vaccine decision. One should only consider administering a vaccine if all four criteria are met:
1. The disease is serious, even life threatening.
2. The animal is or will be exposed to the disease.
3. The vaccine for the disease is known to be effective.
4. The vaccine for the disease is considered safe.
Let's look at individual diseases to see how this works. I'll start with feline leukemia virus (FeLV) disease. An indoor-only cat will not be exposed (number two) as this virus requires direct, intimate, cat-to-cat contact for transmission. Many veterinarians recommend immunizing indoor cats against this disease, but I feel this is unethical. This disease does not fit criteria numbers three or four anyway in my experience, so vaccination is unwarranted in most if not all circumstances. If a vaccine for the feline immunodeficiency virus were developed, it would be the same as for FeLV.
Feline infectious peritonitis (FIP) is another disease that fits neither three nor four, and rarely number two. The FIP virus vaccine has generally been found ineffective and has produced severe side effects. Among the side effects I have observed with both FIP and FeLV vaccines is induction of the clinical disease they were intended to prevent.
Feline panleukopenia virus is very serious and the vaccine is quite effective, but most cats will not be exposed to the virus and the disease generally affects kittens only. Only those cats that are likely to be exposed would benefit from vaccination, and one vaccination between the age of ten to twelve weeks will protect 95 percent of cats for life. (Schultz)
With the feline upper respiratory diseases (calicivirus and rhinotracheitis virus as well as feline chlamydia), most are not serious except in very young kittens. These kittens generally contract the disease before vaccines would typically be administered, so the vaccine is not often beneficial. If you choose to immunize for these, use the intranasal form, and do not vaccinate for chlamydia. The chlamydia fraction produces poor immunization.
Recently a vaccine for ringworm was introduced. I have no direct experience with this vaccine, but I am certain that it will have little benefit and it is probably unsafe. Ringworm is usually the result of immunodeficiency—a chronic disease rather than an acute illness, so the vaccine will not address the cause of disease. I strongly recommend against using this vaccine.
Finally, while rabies is a very serious disease with the potential to infect humans (this is the reason for excessive vaccination laws), most animals are very unlikely to be exposed. One vaccine at four months of age will protect most cats for life. If one booster vaccination is administered, almost all animals (95 percent) are immunized for life. (Schultz)
In summary, my first recommendation is avoidance of vaccination whenever possible. If the risk is great, one panleukopenia vaccination will adequately protect the cat in almost all cases. The intranasal rhinotracheitis-calicivirus vaccine is relatively effective, but very few cats will benefit from this. Finally, rabies is legally mandated, but one vaccination will generally protect cats that are at risk.
I never recommend vaccines for feline leukemia virus, feline infectious peritonitis virus, Chlamydia, ringworm, or the feline immunodeficiency virus. And I never recommend booster vaccines; these are always unwarranted.
Clarence Fraser, ed. The Merck Veterinary Manual (Rahway, New Jersey: Merck & Co., Inc., 1986).
Neil Miller, Vaccines: Are They Really Safe and Effective? (Santa Fe, NM: New Atlantean Press, 1994).
Phillips, T.R., DVM, and Ron Schultz, Ph.D., "Canine and Feline Vaccines," in Current Veterinary Therapy XI, Robert Kirk, DVM and John Bonagura, DVM, eds. (Philadelphia: Saunders, 1992).
Ron Schultz, "Theory and Practice of Immunization" (paper presented at the annual meeting of the American Hol