Soon, veterinary professionals began to suspect vaccination as a risk factor in other serious auto-immune diseases. Researchers surmised that, in some animals, vaccines were stimulating the animal's immune system against his or her own tissues, leading to potentially fatal diseases such as auto-immune hemolytic anemia (AIHA) in dogs. Researchers began to suspect delayed vaccine reaction for the cause of such chronic conditions as thyroid disease, allergy, arthritis and seizures in cats and dogs.
Such observations led to a 1995 Journal of the American Veterinary Medical Association article that concluded there is "little scientific documentation that backs up label claims for annual administration of most vaccines," and that the only vaccine tested routinely for duration is the rabies vaccine. In addition, the article suggested that though some vaccines should be given annually, giving others only every few years would be sufficient because of potential risks associated with them.
Hesitation to Vaccinate
Dodds says that in her own practice, she only vaccinates when necessary. Rather than automatically giving boosters, Dodds gives annual titers, or tests, to check the level of antibodies (disease fighting cells) in the blood to determine if boostering is necessary. Though she expects that immunity would be conferred for life, she says that titers offer "an added measure of security."
Though many vets have in fact begun to change their vaccination habits, many continue to administer annual shots. Dodds believes that the resistance is not so much a financial issue since vets should still asks clients to come in for an annual check-up and titers. Rather, it's more about changing attitudes.
"For decades we were told that this is what we had to do," Dodds says. "The USDA put the recommendation on the label. Our confidence was totally shaken up."
Non-Vaccination a Greater Danger?
Still, many vets believe it's too early to change procedure. The say that until more is known about the immunity conferred by some vaccines, it's best to take a conservative approach. They emphasize the fact that annual vaccinations have been effective at decimating the incidence of formerly common, potentially lethal viral diseases such as feline panleukopenia, rhinotracheitis, feline leukemia, canine distemper, hepatitis and canine parvo virus. And with the incidence of the deadly feline leukemia virus so high, it is too hard and too risky to determine which cats are at risk.
Dr. Donald Klingborg, former Chairman of the Council of Biologic and Therapeutic Agents of the American Veterinary Medical Association (AVMA) and Assistant Professor at the University of California at Davis, says that while the vaccination issue is a complicated one, nonvaccination is a major error.
"In most cases, the threat to the animals' health from nonvaccination is much greater than vaccination," he says. "The diseases are real, severe and common."
Klingborg says the vaccination debate could be settled by more information on the duration of immunity most vaccines impart.
Conclusive Answers Difficult
But while vaccine companies are under no legal obligation to demonstrate duration of immunity, that question may remain unanswered for some time.
Dr. Susan Wynn, a Georgia-based veterinarian and former board member of the American Holistic Veterinary Medical Association says that the problem with obtaining immunity duration information is monetary and political.
"This information would have to be gained by challenge studies in which you give viruses to animals inoculated over five to 10 years ago," she says. "You would have to keep those animals in a controlled environment for this time — only drug companies have that kind of money."
Wynn says that for the drug companies, the decision is based on priorities — it's either more products or immunity studies, not both.