vaccinating pregnant animals. The potential for side effects such as promotion of chronic disease sites in male and non pregnant female dogs receiving this lot of vaccine remains in question, although there have been anecdotal reports of reduced stamina and renal dysfunction in performance sled dogs (3). Recently, a vaccine manufacturer had to recall all biological products containing a distemper component, because they were associated with a higher-than-expected rate of central nervous system Postvaccinal reactions 1 to 2 weeks following administration (3).
If, as a profession, we conclude that we are overvaccinating, other issues come to bare, such as the needless client dollars spent on vaccines, despite the well-intentioned solicitation of clients to encourage annual booster vaccinations so that pets also can receive a wellness examination (5). Giving annual boosters when they are not necessary has the client paying for a service which is likely to be of little benefit to the pet's existing level of protection against these infectious diseases. It also increases the risk of adverse reactions from the repeated exposure to foreign substances.
Polyvalent MLV vaccines, which multiply in the host, elicit a stronger antigenic challenge to the animal and should mount a more effective and sustained immune response (5,6,9). However, this can overwhelm the immunocompromised or even healthy host that has ongoing exposure to other environmental stimuli as well as a genetic predisposition that promotes adverse response to viral challenge (1-3,9,13). The recently weaned young puppy or kitten being placed in a new environment may be at particular risk. Furthermore, while the frequency of vaccinations is usually spaced weeks apart, some veterinarians have advocated vaccination once a week in stressful situations. This practice makes little sense, scientifically or medically (5).
An augmented immune response to vaccination is seen in dogs with pre-existing inhalant allergies (i.e., atopy) to pollens (3). Furthermore, the increasing current problems with allergic and immunological diseases have been linked to the introduction of MLV vaccines more than 20 years ago (6). While other environmental factors no doubt have a contributing role, the introduction of these vaccine antigens and their environmental shedding may provide the final insult that exceeds the immunological tolerance threshold of some individuals in the pet population.
Twenty years ago, this author began studying families of dogs with an apparent increased frequency of immune-mediated haematological disease (i.e., AIHA, ITP, or both) (12). Among the more commonly recognised predisposed breeds were the Akita, American Cocker Spaniel, German Shepherd Dog, Golden Retriever, Irish Setter, Great Dane, Kerry Blue Terrier and all Dachshund and Poodle varieties; but predisposition was found especially in the Standard Poodle, Long-Haired
Dachshund, Old English Sheepdog, Scottish Terrier, Shetland Sheepdog, Shih Tzu, Vizsia, and Weimaraner, as well as breeds of white or predominantly white coat colour or with coat colour dilution (e.g., blue and fawn Doberman Pinschers, the merle Collie, Australian Shepherd, Shetland Sheepdog, and harlequin Great Dane) (1-3). Recently, other investigators have noted the relatively high frequency of AIHA, ITP or both in American Cocker Spaniels (10) and Old English Sheepdogs (13).
A significant proportion of these animals had been vaccinated with monovalent or polyvalent vaccines within the 30-45 day period prior to the onset of their autoimmune disease (1,2,10). Furthermore, the same breeds listed above appear to be more susceptible to other adverse vaccine reactions, particularly Postvaccinal seizures, high fevers, and painful episodes of hypertrophic ostedystrophy (HOD) (3). For animals that have experienced an adverse vaccine reaction, the recommendation is often to refrain from vaccinating these animals until at least after puberty, and instead to measure serological antibody titers against the various diseases for which vaccination has been given. This recommendation raises an issue with the legal requirement for rabies vaccination. As rabies vaccines are strongly immunogenic and are known to elicit adverse neurological reaction (3,5) it would be advisable to postpone rabies vaccination for such cases. A letter from the primary care veterinarian stating the reason for requesting a waiver of rabies vaccination for puppies or adults with documented serious adverse vaccine reactions should suffice.
As further examples, findings from the author's large accumulated database of three susceptible breeds are summarised below._____________________
Vaccine-Associated Disease in Old English Sheepdogs.
Old English Sheepdogs appear to be predisposed to a variety of autoimmune diseases (1-3,13). Of these, the most commonly seen are AIHA, ITP, thyroiditis, and Addison's disease (2,17). Between 1980 and 1990, this author studied 162 cases of immune-mediated haematological diseases in this breed. One-hundred twenty-nine of these cases had AIHA, ITP, or both as a feature of their disease. Vaccination within the previous 30 days was the only identified triggering event in seven cases and was an apparent contributing factor in another 1 1 5 cases (2). Thyroid disease was recognised as either aprimary or secondary problem in 71 cases, which is likely an underestimate of the true incidence, as thyroid function tests were not run or were inconclusive in most of the other cases.
Experience with a particular Old English Sheepdog family supported a genetic predisposition to autoimmune thyroiditis, Addison's disease, and AIHA or ITP or both - an example of the polyglandular autoimmune (2,17). Pedigrees were available from 108 of the 162 Old English Sheepdog cases of autoimmune disease; a close relationship was found among all but seven of the