Below is the first in a series of timely articles on pet vaccinations appearing in the current issue of Animal Wellness Magazine. In the article, they extensively quote Dr. Ronald Schultz, Chair & Professor of Pathobiological Sciences at the University of Wisconsin School of Veterinary Medicine, whose challenge studies form the base of the American Animal Hospital Association's.
“I have studies that show duration of immunity at seven to nine years for all the core vaccines except rabies, and even on an antibody basis I can show that rabies gives much longer protection than three years,” says Dr. Schultz.
Although AAHA recommends vaccinating against distemper every three years after the initial puppy shots, challenge studies have shown that the minimum duration of immunity can last five to seven years, and perhaps even longer. In fact, titers have indicated that dogs can be protected for nine to 15 years. “To be honest, although canine distemper is a core vaccine, I think a dog only needs to receive it once in his life,” says Dr. Schultz. “The same goes for canine parvo and adenovirus-2. That’s the vaccination program I’ve been practicing on my own dogs without any difficulty whatsoever. We’ve never had a vaccine-preventable disease occur.”
Vaccination:
Which ones do they REALLY NEED, and HOW OFTEN?
by Ann Brightman
When Helena took her new Sheltie puppy, Mick, to the vet for his first check-up, she felt more than a little anxious when it came time for him to receive his shots. While she wanted to protect her new friend from deadly diseases like distemper and parvo, she was also concerned about the health risks associated with over-vaccination. Although Helena went ahead with the vaccines and follow-up boosters, she was worried about subjecting Mick to subsequent annual shots, even though her vet told her she was risking her dog’s health even more by not doing so.
It’s a common quandary these days, especially as we hear more and more about the often devastating side effects of over-vaccination. How do we prevent our dogs or cats from contracting infectious diseases that can often be fatal, while also protecting them from the equally serious health consequences of too many shots? The best strategy is to learn which vaccines are absolutely necessary (referred to as core vaccines), why they’re needed, and what the minimum requirements are for each to ensure protection from disease without over-vaccinating.
WHAT ARE CORE VACCINES?
“Core vaccines are those that every dog or
cat should receive, regardless of geographic location or lifestyle,” says
Dr. Ron Schultz, Professor and Chair of the Department of Pathological
Studies at the University of Wisconsin-Madison’s School of Veterinary Medicine.
For dogs, the four core vaccines are canine distemper (CDV), canine parvovirus-2
(CPV-2), canine adenovirus-2 (CAV-2) and rabies. In this article, the first
in a three-part series, we’ll be taking a close-up look at canine distemper,
feline panleukopenia and rabies.
The four vaccinations listed above are considered core because the diseases they protect against are distributed over a wide area and have a high mortality rate. These vaccines are absolutely necessary,” says Dr. Schultz. “You want the vaccine to be the first antigens to prime the immune system. You don’t want to leave it up to natural immunization or exposure.” This is because, when compared to the actual disease-causing virus, the vaccine is a safer way to protect the animal. “If the vaccine is live, it’s attenuated. If it’s killed, it can’t cause disease,” explains Dr. Schultz. “It’s true that many puppies that never see a vet get naturally immunized by exposure to distemper, as an example, but for every one that gets vaccinated, probably another would have died if the first encounter with distemper occurred prior to vaccination.”
MINIMIZING VACCINATION
Although core vaccines are necessary to protect your companion from infectious disease, even these do not need to be given on an annual basis. “That’s what we’re trying to change,” says Dr. Schultz. “What we recommend is that both puppies and kittens get the core vaccines at least once at or over the age of 12 weeks.” The 12 weeks is significant, because prior to that, many animals still have passive maternal antibodies that block immunization, which means they may not respond to the vaccine and are therefore unprotected against the disease. American Association Hospital Association (AAHA) guidelines recommend vaccinating again at one year, and once every three years after that, although even that may not be necessary. “I have studies that show duration of immunity at seven to nine years for all the core vaccines except rabies, and even on an antibody basis I can show that rabies gives much longer protection than three years,” says Dr. Schultz.
CANINE DISTEMPER (CDV)
CDV is a highly infectious and often fatal disease that attacks the respiratory, gastrointestinal and central nervous systems. Although dogs of any age can contract distemper, puppies up to six months of age are most susceptible to the disease, which can cause a range of symptoms from fever, loss of appetite and eye inflammation in its early stages, to diarrhea, vomiting, pneumonia, and neurological complications such as ataxia, seizures and paralysis.
Canine distemper occurs around the world not only among domesticated dogs, but also in many wild carnivores such as raccoons, skunks and foxes. “Wildlife is actually now more of a reservoir for distemper than dogs are,” says Dr. Schultz. “The virus is spread mainly by air, or by direct contact with secretions from the infected animal. The mortality rate among puppies with distemper is 50% or higher.” On the plus side, the distemper virus is very fragile and easily destroyed by outside influences. “It doesn’t live very long in the environment,” says Dr. Schultz. “It dies very quickly because it is what we call an enveloped virus. These kinds of viruses are highly susceptible to water, disinfectant and sunlight.”
Titer testing is highly effective for canine distemper, but according to Dr. Schultz, the best time to do it is at two weeks or more after the last puppy vaccination, to ensure that the animal responded to its initial vaccines. “To my mind, that’s the only time it’s of medical benefit to use a titer test for canine distemper. After that, you don’t really need to titer the animal since you can easily go five or seven years before the next vaccine.”
RABIES (RV)
Unlike distemper and parvo, rabies is a disease that can be transmitted from animals to humans, which is why rabies vaccinations are required by law throughout North America. The virus infects the central nervous system, causing encephalitis and death. Symptoms can include confusion, partial paralysis, aggressive behavior, excessive salivation and other neurological signs. Although rabies occurs worldwide, including in Asia, Africa and Latin America, some countries such as the U.K. are rabies-free. In North America, rabies is most prevalent in the eastern portions of the continent, although cases can occur anywhere. Wild animals such as raccoons, skunks, bats and foxes are the major carriers. Because rabies isn’t age-related, mammals at all stages of life can be affected with the same degree of severity. The chief means of transmission is by a bite from an infected animal.
“There are multiple strains of rabies, but the important thing is that the vaccine prevents infection with all those different strains,” says Dr. Schultz. “Although the risk of infection in domesticated animals is generally low, the public health concern is the issue. That’s what drives the regulations for rabies vaccines.” As with the other core vaccines, puppies and kittens should be vaccinated at 12 weeks. Although some states and provinces have approved a three-year rabies vaccine, some still require annual re-vaccination for dogs and cats, even though the duration of immunity based on challenge studies has been shown to be three to seven years. “The regulations vary from state to state and province to province, and even from municipality to municipality.” It’s also important to realize that a municipality might have a more restrictive requirement than the state or province it’s a part of, although not the other way around.
“Rabies titers are effective, but there’s no point running them because you’re going to have to vaccinate your animal by law anyhow,” says Dr. Schultz. However, titer testing for rabies is useful in cases where the animal has had an adverse reaction to the vaccine, or has a medical condition that could be aggravated by the vaccination. “In these situations, local municipalities will sometimes accept a letter from the vet as a reason not to vaccinate every three years, But the guardian has to understand that the animal is still considered to be non-vaccinated, and if it bit someone, it would be treated as such if it’s gone beyond the three years, irrespective of the vet’s letter. Even so, if you have a dog that for health reasons shouldn’t be given a rabies vaccine, it’s better to take the chance of it being quarantined for biting someone than to give the vaccine and kill the dog.”
BACK TO BASICS
Vaccinations definitely have their place in disease prevention, but knowing where to draw the line is key. “I’ve seen it go from no vaccines back in the mid-1960s, to where we just kept adding one after the other,” says Dr. Schultz. The pendulum has since started swinging back again as organizations such as AAHA and American Association of Feline Practitioners (AAFP) began looking more closely at which vaccines out of the 12 for cats and 16 for dogs were really needed and why. “We used to have one manufacturer that made a canine vaccine combo with 13 different components in it. That’s not good, and that’s why it’s not available anymore.” Now, by contrast, companies are coming out with information demonstrating that their products give duration of immunity lasting several years. “All the major manufacturers are coming on board and saying that their core vaccines give at least three years immunity. To me, that’s the greatest gratification in the more than 25 years I’ve been doing this.”