New Vaccination Guidelines

Colorado State University's Small Animal Vaccination Protocol

Tailoring this healthcare necessity to fit your dog’s needs
By Caroline Coile,.PhD  

Source: “Dog Watch: The Newsletter for Dog People”,
, College of Veterinary Medicine 75 Holly Hill Lane
Greenwich , CT    06830

It's what dog owners have been told to do for years: Vaccinate thoroughly and vaccinate often. But that practice has now come under scrutiny, leaving many tesponsible dog owners vacillating about vaccinating.

Vaccination should not be a regimented, one-size-fits-all procedure, according to Cynda Crawford, DVM, PhD. Dr. Crawford, of the University of Florida School of Veterinary Medicine, is one of a growing number of veterinarians and researchers who are striving to define guidelines in an effort to help dog owners and veterinarians "give the right vaccine at the right time to the right individuaL" That means that every vaccination should be evaluated in terms of a dog's age, lifestyle, potential for exposure, and consequences should the dog become infected.  

Some vaccines—called core vaccines—protect against such devastating or widespread threats that it's necessary for every dog to receive them. Core vaccines include those for distemper, infectious hepatitis, parvovirus, parainfluenza virus and rabies. Other vaccines - called non-core vaccines - protect against less dangerous or more localized diseases, and are not for every dog.

So it's not just a question of what vaccinations to give, but how often to give them. For the past 20 years, the American Veterinary Medical Association has recommended revaccinating dogs annually as the safest way to ensure all dogs had sufficient immunity. But that practice has also come into question because many vaccines protect dogs for longer than a year. Vaccine manufacturers must demonstrate their vaccines are effective for the duration claimed on their labels. To do this, they expose dogs to the disease-causing organism at various times following vaccination. Because such studies are expensive, most manufacturers stop them after demonstrating the vaccine protects for a year. The vaccine is then labeled for one-year immunity, giving rise to the recommendation for annual revaccination. However, recent studies performed by independent groups have shown that modified live vaccines for distemper, parvovirus, canine infectious hepatitis and parainfluenza protect for at least five to seven years. Based on such studies, many veterinary schools are now recommending revaccinating at three-year intervals as opposed to yearly.  

Dr. Crawford feels that we are probably vaccinating dogs with too many vaccines too often. But what is the harm? Some vaccinations may cause transient adverse reactions or even a mild form of the disease they're protecting against. Modified "live" vaccines such as those for distemper, parvovirus, canine infectious hepatitis, parainfluenza and kennel cough - can cause disease in some animals.  

"Killed" vaccines - such as those for coronavirus, leptospirosis, kennel cough, Lyme disease, giardia and rabies - are mixed with an adjuvant, usually aluminum hydroxide, that boosts the immune response to the vaccine but also increases the chance of adverse reactions.  

Adverse reactions may include localized swelling, pain or hair loss; or anaphylaxis, with hives, itching, and vomiting or diarrhea. About 10,000 adverse reactions to vaccines in animals are voluntarily reported in the United States each year. In the United Kingdom , where adverse reactions must be reported, the percentage of adverse reactions is less than 0.1 percent of vaccine doses sold.  

Of more widespread concern is the fear that vaccinating too often may lead to certain chronic diseases in some susceptible individuals, or to certain immune-mediated disorders, particularly immune mediated hemolytic anemia. Several reports have linked vaccination to the development of immune-mediated joint, neurological and thyroid diseases, but as yet no controlled study has shown a cause-and-effect relationship.  

Some pet owners, uneasy about the possibility of either over- or under-vaccinating, turn to antibody titer checks to evaluate a dog's level of immunity to a particular disease. Unfortunately, titer levels do not necessarily correspond with immunity levels. High titer levels don't guarantee immunity, and low titer levels don't guarantee susceptibility. No standardize tests or interpretations are available, so samples sent to different laboratories may produce different recommendations. Because titers are based on humoral immunity, they cannot evaluate other important components such as immune memory cells or cell-mediated or mucosal immunity.  

Other pet owners turn to nosodes or natural substances in place of traditional vaccinations. (Homeopathic nosodes are orally administered products made from highly diluted infected material.) Many well-meaning owners do this with inadequate information, and end up with unprotected dogs. In the only controlled study of their efficacy, nosodes against parvovirus were shown to be totally ineffective in preventing disease.  

On the horizon are more genetically engineered recombinant vaccines that produce immunity through cell-mediated immune mechanisms. Such vaccines are considered less likely to produce adverse effects, but also may be less likely to produce titer indicators of immunity.  

The American Animal Hospital Association (AAHA) plans to issue updated canine vaccination guidelines in the spring of 2003. Although the report is not yet public, there is speculation that it will also advocate a national reporting system to document adverse reactions to vaccines, improvements in vaccine labeling, and three-year rabies boosters. Dr. Crawford points out, "The overall goal of vaccination is protection of the population as a whole, which can be achieved by vaccinating more dogs, but vaccinating each dog less."