Vaccinations have truly been among the most significant medical advances of our time. They have likely saved more lives than all other medical advances combined. Most of us have been spared the ravages of infectious diseases that once decimated populations of our ancestors. These diseases, or new ones, continue to be an incessant threat to animals and man alike. It is only with constant vigilance for the emergence of these diseases and widespread participation in vaccination programs that we are free of most of these concerns.
The unchallenged tenet of medical practice is "first, do no harm". A variety of adverse reactions to vaccines have been noted since the early days of their development. If the frequency of these reactions is low, or the nature of the reaction is mild, then the benefit of staving off a potentially fatal disease is clear.
What happens when the disease is mild, the disease is extremely rare, or the vaccine does not confer complete protection from the disease? Under these circumstances, any adverse reaction to a vaccine may not carry an acceptable risk.
Historically, immunizations in veterinary practice have ranged from highly effective vaccines against uniformly fatal diseases, to possibly less effective vaccines against common, but usually not fatal, infections. The rationale and benefits of vaccination in the first circumstance is obvious. The rationale for the latter situation has been that these vaccinations may help some animals in some instances, but above all, they do no harm.
Enter feline vaccine induced sarcoma.This is a particularly aggressive cancer of cats that appears to arise at sites on the body where inoculations are typically administered. The increase in the occurrence of these cancers has paralleled increases in the numbers and types of vaccinations given to cats.
Now the comfortable position that veterinarians have enjoyed of "probably helping and certainly not hurting" is no longer tenable. The professional is now torn between needing to protect pets from the very real and ever-present threat of severe infectious diseases and the realization that their well-meaning actions may seriously harm a small number of pets they treat.
At the risk of inducing panic among pet owners, the reader should understand that the incidence of these vaccine induced problems is extremely low, and the tremendous benefits of inoculations is unquestioned. There is, however, little consolation for the cat and owner who are informed that they are a one-in-ten thousand case.
What is acceptable risk? What can we do as a profession to protect our patients and yet minimize their risks? There is much current research attempting to answer such questions and establish guidelines. Which vaccines or components of vaccines are responsible for problems? Should we be vaccinating more aggressively for some diseases and less aggressively for others? Unfortunately, biologic systems are so complex that information tends to accumulate slowly and from many different research groups. Studies then need to be independently confirmed, and funding secured, etc., etc.
What individual veterinary practitioners can do immediately, however, is perform a detailed risk assessment of every veterinary patient. Does this cat's lifestyle dictate that he is at greater risk for contracting disease "X"? Does this dog's circumstances suggest he is not ever likely to encounter disease "Y"? Is disease "Z" of such a horrible nature that failing to vaccinate for it in any situation would be reprehensible?
All our pets have different lifestyles. Infectious diseases exploit the varied nature of lifestyle. Our clients at San Carlos Veterinary Hospital are noticing, or will notice soon, that their pets are receiving vaccines that are likely different from those they have typically received. They will be asked specific questions about their animal's circumstances, and a vaccination protocol will be tailor-made for that pet. Some will be administered inoculations for many diseases, others for fewer. Some may receive vaccines more often, others less often.
Unfortunately, answers always lag behind the questions. Until such time as meaningful information begins to appear in the veterinary literature, we, as veterinarians, must posture ourselves to do our public duty to protect our animals from devastating disease and once again, do no harm.
Further Reading:
AVMA Vaccine-Associated Feline Sarcoma Task Force
Cat Fancier's Association: Vaccination Protocols for Catteries