Dear Dr. Walt: I have a question concerning vaccinations: must I get my 2-year-old cat vaccinated against rabies, distemper, leukemia, etc.? When we got him as a kitten at the veterinarian's, he had been dewormed, vaccinated, and fixed. Since then, he has been kept strictly indoors and has no other contact with dogs or cats. I am leery of all these injections and their possible effects on his system. Since ‘Henry' doesn't go out nor have contact with other animals, must we still get him vaccinated? Why inject chemicals into his system when they may not be necessary?

You ask some good questions, questions that the veterinary profession is working hard at solving as well. Issues pertaining to vaccination – both the frequency and type of vaccines used – have become a “hot topic” of debate in both the veterinary and pet community. Because the duration of protection following vaccination isn't well researched, the veterinary community has, up until now, adopted an annual vaccination policy to coincide with the annual rabies vaccination. Only rabies vaccinations have a well researched and known duration of immunity allowing the frequency to be better defined; for most rabies vaccines the manufacturer's recommendation is for every three years except in endemic areas (areas where rabies is really prevalent such as Ontario) where yearly vaccination for rabies is recommended. Rabies revaccination is mandated by provincial law – you have no choice on this one!

Vaccination can result in many different outcomes and, fortunately, the most common outcome is also the most beneficial to our animals – protection against disease. The advent and implementation of vaccinations have had a tremendously positive impact on the health and welfare of our pets through the reduction of many infectious diseases that were often fatal. Examples include distemper in dogs and cats, parvovirus in the dog, and let's not forget the invariably fatal rabies, which has been dramatically reduced in both animals and people!

However, untoward reactions to vaccinations do occur. The most common is an allergic reaction that can present in varying degrees of severity from a mild restlessness, itchiness and hives to facial swelling and, in more severe cases, anaphylactic shock. These reactions are unpredictable and once a pet's predisposition is identified, these reactions can be controlled through altering the vaccine used, its frequency, or by the concurrent use of medications to control the reaction. These reactions are similar to more commonly known reactions including penicillin or nut allergies. Fortunately they are rare.


Page 1 of 2 -- On page 2, learn what other risks vaccinating your pet could pose.

Other reactions to vaccines can be far more serious. Many of those that have caught the attention of the pet community are anecdotal, or in other words, unsubstantiated rumour with a clear association between vaccination and the purported disease in question not having been clearly defined.

One condition that has been shown to be correlated with vaccination is the occurrence of a particular type of cancer, called sarcoma, in the areas that vaccines have been administered in some cats. The cause is thought to be an over-exuberant immune response to the vaccine that subsequently causes the local tissue to transform into cancer. It is extremely rare, occurring in approximately 1:10,000 vaccinated cats and is also unpredictable but thought to have a genetic component. This association was discovered through the many different surveillance programs in place that monitor disease occurrence and reactions to medications (including vaccines) in pets. By reporting an adverse reaction to your veterinarian, he/she will forward this on to both the product manufacturer as well as the regulatory agency that oversees the pharmaceutical industry thereby ensuring that if problems do occur, they are identified quickly and corrective measures put into place. In the case of feline vaccinations, if you notice a lump in the area that the vaccine was given that lasts longer than 4 to 6 weeks, have your veterinarian examine the area and ensure it is of no concern. Newer generations of vaccines are far safer and more refined and should significantly reduce the occurrence rate of reactions. For cat owners wanting more information on this subject, give your veterinarian a call to discuss it further.

The one significant outcome of all the discussions on vaccines, has been a refocus of the vaccine protocols used to meet the needs of the individual animal. All kittens (and puppies) should have an initial vaccine series that is boostered at one year of age with subsequent, annual visits to your veterinarian. It is during your pet's annual general physical examination and preventative health care visit, that your veterinarian will determine both the health of your pet (therefore the ability to safely administer the vaccines needed) as well as your pet's risk for the various infectious agents that vaccines are available for. In some situations, your veterinarian may recommend a blood test to determine whether antibodies against certain, critical infectious agents are sufficient to prevent infection or a booster vaccination is required. Then a final decision can be made as to the specific vaccine protocol to be used in your pet. The result is that some pets (i.e., indoor, apartment-dwelling cats for instance) may not require yearly vaccinations (unless they are boarded), whereas others (especially the active outdoor types) might still benefit best from annual vaccinations.


Page 2 of 2 -- On page 1, Dr. Walt outlines the benefits of vaccinating your pet.

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 About Dr. Walt Ingwersen
Dr. Walt Ingwersen is Chief Veterinary Officer at PetCare Insurance Brokers Ltd. He is a 1982 graduate of the Ontario Veterinary College. Board certified in Internal Medicine, he has the distinction of being the first Canadian editor of the Journal of the American Animal Hospital Association, a position he currently holds.

Involved in many aspects of the national and international veterinary community, "Dr. Walt" is the recipient of the President's Award for outstanding contribution to the veterinary profession awarded by the Canadian Veterinary Medical Association (CVMA). He is also Chief Veterinary Officer and Chairman of the Veterinary Advisory Board at PetCare Insurance Brokers Ltd. -- Canada's leading provider of insurance for dogs and cats.