Vaccinations Update

From Animal Issues, Volume 31, Number 3, Fall 2000
Vaccinations Update
By Jean Hofve, D.V.M.

In "Are We Vaccinating Too Much?" (Animal Issues, Fall 1998), Dr. Elizabeth Colleran explored the burgeoning controversy in the veterinary community over annual vaccinations, and the possible ill effects from giving our companion animals too many vaccines. Since then, there has been a great deal of research, and even more passionate debate. But what, if anything, has really changed?

Veterinarians can be very resistant to change. Unfortunately, the weight of this inertia, added to the potential loss of revenue from vaccines, has resulted in little overall shift toward less vaccination among practitioners. Well documented adverse effects include feline vaccine-induced fibrosarcomas (a malignant connective tissue tumor), which form at the injection site, and auto-immune hemolytic anemia (AIHA) in dogs. Even with aggressive treatment, cats with these tumors rarely survive more than a year, and AIHA is equally deadly. Research has suggested a link between vaccines and immune-mediated polyarthritis in dogs. Hypertrophic osteodystrophy, a painful bone disease, appears to be triggered by the distemper vaccine in some Weimeraners. Some dog breeds, notably Dobermans, Rottweilers, and Akitas, seem especially prone to deleterious reactions.

Autoantibodies

A recent study at Purdue University found that all vaccinated dogs develop "auto-antibodies" (antibodies mis-directed at the dog's own tissues) against common mammalian proteins such as albumin, and even to DNA. This occurs because the viruses and bacteria used in vaccines are grown in cell cultures and nourished with calf serum. When the organisms are harvested for inclusion in vaccines, they are filtered, but nonetheless some bovine serum proteins get through and are included in the vaccine itself. When injected, these foreign proteins cause antibodies to be formed which may then react against the canine versions of the same proteins. Purdue found autoantibodies in every vaccinated dog, and noted an increase in autoantibodies after each subsequent vaccination. Autoantibodies are associated with diseases such as Lupus, hypothyroidism, and cardiomyopathy. A long-term follow-up study is monitoring dogs to see how many actually develop autoimmune disease.

Dr. Dennis Macy, at the Colorado State University (CSU) Veterinary Teaching Hospital, feels that most vaccinations do not need to be administered annually. CSU's Small Animal Vaccination Protocol (www.cvmbs.colostate.edu/vth/savp2.html) recommends a very limited "core" set of vaccines for dogs and cats. For puppies and kittens, an initial two- or three-vaccination series is followed by boosters given only every three years in adults. For dogs, CSU recommends a "four-way" (four-in-one) vaccine against distemper, parvovirus, adenovirus 2 (infectious canine hepatitis), and parainfluenza.(a component of kennel cough). Cats receive a "three-way" vaccine including feline panleukopenia (distemper), rhinotracheitis (herpes) and calicivirus (upper respiratory viruses). He does not recommend the feline leukemia vaccine for most cats under normal circumstances, and even in high risk cats it is limited to a two-vaccine kitten series and a single booster at one year of age. Also missing from CSU's protocol are feline vaccines containing Chlamydia (an upper respiratory bacterium), and the problematic FIP (Feline Infectious Peritonitis) vaccine.

Rabies vaccination is required by law in most states and municipalities, and must be current to transport an animal across state lines. Rabies exists to some extent in all parts of the continental U.S., and poses a significant risk on the eastern seaboard and near the Mexican border. It is the only legally mandated vaccine in companion animals. For dogs, rabies can be given at 16 weeks of age, and after 12 weeks of age in cats. For cats, CSU recommends only the Purevax rabies vaccine by Merial, a recombinant virus in a canarypox carrier. This is the only rabies vaccine for cats that avoids the risk of vaccine-site fibrosarcomas. If your veterinarian does not use this product, ask her to order it for you. It's your cat's life at stake!

New Vaccines

There have been several new vaccines introduced in the past few years, including ringworm (a fungal skin infection), Giardia (a protozoal intestinal parasite), feline Bordatella (similar to canine kennel cough, and thought to be a factor in many upper respiratory infections in cats), canine Coronavirus (a mild self-limiting diarrhea of puppies), Leptospirosis (affects the kidneys), and Lyme disease. The ringworm vaccine is unusual in that it does not prevent the infection, but can stimulate the immune system to overcome an existing infection in some cases. A large percentage of canine Lyme disease cases are actually caused by the vaccine. However, a new vaccine was recently introduced by Rhone-Merieux that may circumvent this problem by using only a portion of the bacteria's DNA. The Leptospirosis vaccine is associated with a high incidence of serious and even life-threatening adverse reactions. None of these vaccines is routinely recommended by CSU or most other veterinary schools.

New vaccines under development include Feline Immunodeficiency Virus (FIV, the cat equivalent of HIV), and Toxoplasma gondii, a parasite that causes birth defects if women are initially exposed in the first trimester of pregnancy. The latter promises to be a very popular vaccine, even though 40% of adult humans in the U.S. have already been exposed and are immune, infected cats only shed the parasite for 1-3 weeks in their entire lives, and the risk of this disease is higher from gardening or consuming rare meat.

What to Do?

Be sure to discuss all vaccination decisions with your veterinarian. Ask for justification for each vaccine recommended, and be sure you understand the risks associated with each one. If your veterinarian seems dismissive or tells you there are no risks, get another opinion. Try to reach a mutually acceptable vaccine schedule for your animals. Adult animals can be boostered every three years (or even less often), rather than annually, for the important "core" vaccines. Space initial puppy or kitten vaccines at least three weeks apart. Each vaccine demands a significant immune response and requires considerable resources from the body. This delay allows the immune system time to completely respond to one vaccine before getting the next one.