I firmly believe owners deserve to be well informed about every medical treatment their pet receives. And vaccines are one of the most common, as well as one of the most potent, medical treatments veterinarians administer. They are also a common cause of adverse reactions, some which can be very serious. I’d like to share some insights and personal experiences with you.
Late afternoons are always busy at a veterinary hospital, as people schedule their routine appointments after work, or come home to find a pet with a problem. Just when the end of the day is in sight, a call comes in. Rocky the Pug, who was vaccinated at 4:30 today, is on his way back, with a badly swollen face and rapid breathing. A vaccine reaction.
Vaccines have long been used in humans and animals, and have saved countless lives. From smallpox to tetanus to rabies, vaccines have protected our pets, our food animals, and us. When new diseases or strains have emerged, vaccines have been updated to keep pace with new threats. Today’s vaccines are extremely potent, and can produce high levels of immunity with just a single dose.
Vaccines stimulate the immune system to develop antibodies and cellular immunity to the disease in question. A vaccine exposes the body to an antigen — a key part of the disease causing virus, or the actual virus that has been killed or modified. The body reacts to the vaccine by producing antibodies, specific white blood cells that attack virus and bacteria infected cells, and memory cells.
The most crucial part of the immune system that enables vaccines to work is the memory cell. These cells have the “imprint” of the disease-causing organism, for example, parvovirus. Should your dog be exposed to parvovirus after being vaccinated, these memory cells reproduce very rapidly, stimulating rapid antibody production and activation of white blood cells. The end result is that your dog does not get the disease. Many memory cells survive three years or more.
It is obvious that vaccination can be very beneficial. However, some individuals may be sensitive and react to the antigen or other compounds in the fluid of the vaccine. Common reactions include hives, facial swelling, fever, respiratory distress, vomiting, diarrhea, or pain at the injection site. Reactions can occur almost immediately, or within days of vaccination. In severe cases, cardiovascular collapse and death can occur. Fortunately these cases are rare.
Rocky, the dog seen at our hospital, arrived an hour after receiving a vaccination. The antihistamine Benedryl® his quick thinking owner had given was starting to help. Antihistamines block the release of the biochemical histamine from the stimulated white blood cells. Histamines cause for airway constriction, itching, and hive formation. He was treated with corticosteroids to suppress inflammation and block excessive immune system response, as well as further antihistamines. Within the hour, his facial swelling and breathing were improving.
Fortunately for Rocky, our knowledge of vaccines and immunology has greatly progressed in recent years. The days of the yearly “booster shot” are long behind us. The American Veterinary Medical Association (AVMA), the American Animal Hospital Association (AAHA), and most veterinary colleges agree that after a puppy series, most vaccines do not need to be given any more frequently than every three years. Some studies have suggested that immunity from commonly used vaccinations lasts seven years or more. There is no benefit to giving an additional vaccination to the dog that already has sufficient immunity. Even more importantly, some experts consider repeated vaccinations as a cause of autoimmune diseases, including immediate reactions like Rocky’s, destruction of red blood cells or platelets, and hypothyroidism. All of these problems can have serious effect on our dogs’ lives.
Many veterinarians have changed their vaccination protocols, following the recommendations of the AVMA and AAHA. These organizations suggest determining which vaccines are essential or “core”, taking into account geographic differences, exposure, previous vaccinations, and effectiveness of the vaccine. Diseases such as parvovirus, rabies or distemper are considered essential. These vaccines are given in a puppy series, then on a three-year interval as the dog reaches adulthood. Vaccines such as Bordetella (kennel cough) or Lyme are often considered “non-core” and are given on a case-by-case basis. For animals with no exposure, there is no benefit in receiving the vaccine.
Several major vaccine manufacturers have responded to the call for longer intervals between vaccinations by proving their products have a three-year duration of action. Currently there are vaccines for distemper, parvovirus, and adenovirus proven to last at least three years. (Some authorities have reported that most current vaccines produce immunity lasting longer than three years.) Rabies vaccine has long been documented to last at least three years.
Given that both of the largest veterinary associations, veterinary colleges, and even vaccine manufacturers are recommending extended vaccination protocols, it is bewildering and dismaying to hear of dogs receiving yearly vaccinations. While some veterinarians are extremely progressive and incorporated extended vaccination protocols years ago, others still recommend yearly vaccinations or non-essential vaccines. Keep in mind as your dog’s owner, you may accept or decline any recommendation. It is your right and responsibility to decide what is in your dog’s best interest. The only vaccination you are obligated to keep current is rabies. Each state has their own laws pertaining to rabies vaccination of animals, so be sure to check your state’s requirements.
So which vaccinations should your dog receive, and when should they be given? In my practice I start with a basic vaccination schedule and modify it individually for each animal. Changes may be made as circumstances change, including vaccine reactions such as Rocky experienced. Dogs with vaccine reactions generally never receive vaccination for that disease again, and are carefully monitored with any other vaccines. Depending on the case, blood testing (titers) may be used to measure the level of antibodies against disease. While these titer tests are not a perfect measure of immunity, they are safe way to determine antibody levels.
Early in my veterinary career, I was confronted with cases of parvovirus daily. Sadly, many of these did not survive. Currently, I may see one case a year. I believe the reason for this is the effectiveness of our parvovirus vaccines. When I began practicing, it was common procedure to give multiple vaccinations at one time, or to vaccinate twice yearly in show and competition dogs. Vaccine reactions were extremely rare. Now, we see many reactions, even to single vaccines. I believe the explanation for these events is the advanced technology and high potency of our vaccines, coupled with what we now know to be too frequent administration. The days of a simple, harmless, “shot” are long gone. We need to view vaccines as the powerful chemical and biological agents they are, and use them with care.
Want to learn more? Check out some info from the Rabies Challenge Fund.
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