This week we’ll get to the real grit that inevitably comes up when vaccinations are discussed. I had hoped that the most current set of recommendations from one of our oversight committees would be published in time to include them in this post. Unfortunately, as far as I know, they’re not yet out in the wild. I’ll touch on that a little as we go along with the discussion.
I’ve got a number of specific things that I definitely want to bring up. I’ll be keeping a close watch on the comments, as always, so please ask questions! This is an opportunity for you to find out about the aspects of vaccination that we don’t often get to talk about during visits. I may even utilize questions in the comments for additional posts.
I want to state right up front that with each patient, we evaluate whether the benefits of vaccination outweigh the risks of vaccination. We don’t take vaccines lightly. They’re essentially a drug, and there are side effects and complications and potential adverse effects from administering a vaccine. While the rate of reactions is quite low for most vaccines out there on the market, the complications can be severe. For each patient, we determine the risks of the patient’s lifestyle and recommend appropriate vaccines. We strive to minimize the number of vaccines given to all patients.
Vaccinations are an area of medicine that is under intense scrutiny by veterinarians, human health professionals, pet owners and parents. This is a heated topic to say the least, but I’m thankful for any respectful debate. We can only learn more and try to apply that knowledge to better care for our patients. I hope that our clients feel that we aren’t just accepting old dogma for our recommendations. I was certainly proud to find out that we are in compliance with the most current recommendations for canine and feline vaccination according to the oversight groups.
Reactions to a vaccine are varied both in severity and frequency. They span the range of very mild problems like being sleepy for a day or being a little sore, on up to life-threatening anaphylactic reactions. The overall reaction rate for the vaccines we use is honestly really low. We used to see a lot more reactions — at least a few a month. Now, I’m surprised to see one every few months.
Pain and soreness are easily countered by giving a dose or two of an anti-inflammatory (an NSAID). Occasionally we’ll have a little inflammatory nodule under the skin that goes away within a few weeks. Those nodules are usually due to the Rabies vaccine, which has an adjuvant.
Severe reactions may include signs like vomiting, diarrhea, weakness, and shock. Pets have to be treated with an injection of Benadryl and a Glucocorticoid steroid, or in very severe cases, epinephrine. I’ve had to give IV fluids, epinephrine, and the benadryl and steroid to just a few patients in the 10 years I’ve been a practicing veterinarian. Even the animals that go into anaphylactic shock are relatively easy to save. They bounce back quickly once the medications are on board. In the future, these pets are given medication prior to the truly necessary vaccines to prevent a reaction. We stretch out the frequency of vaccines and try not to give too many in one visit. Most patients do really well, and we’ve been able to have the benefits of vaccination outweigh the risks so that patients are protected from deadly diseases without suffering the reactions from the vaccines.
Adjuvants, Vaccine-associated Sarcomas, and other Vaccine Complications
As we discussed in the earlier posts, some vaccines contain an additional ingredient with the sole purpose of increasing inflammation in the spot the vaccine is administered. This irritating substance causes white blood cells to move into that area and subsequently be exposed to the pathogen in the vaccine. The idea here is that for killed pathogen vaccinations, the dead virus/bacteria alone wouldn’t be enough to stimulate an adequate immune response. The adjuvant creates that immune response through irritation/inflammation. The trouble, of course, is that you’re injecting a lipid or a metallic substance that causes significant inflammation and tissue damage. It’s difficult to know how much is exactly enough, and the sweet spot between adequate response and an overblown response isn’t always easy to hit, either. The complications from this aren’t very common — 1 in 1000 to 1 in 10,000 for most — but they can be severe. If your pet happens to be that 1, it doesn’t matter how many did NOT have the problem.
One of the complications that can arise is an immune response that ends up attacking another part of the body. Usually, it’s the red blood cells or platelets. This is clearly a very serious disease (immune-mediated hemolytic anemia or immune mediated thrombocytopenia) that requires aggressive treatment. Patients can die from these complications. There is a theory that thyroid problems in dogs may be linked to overvaccination with the DHPP vaccine. There’s no conclusive proof published that I’m aware of. I’ve had one case of anemia that I know was associated with vaccination in the 7 years I’ve been at Pet Authority. That patient survived and is doing very well. She leads a normal life, but we don’t vaccinate her anymore for fear of triggering a relapse.
Cats can have a very unique and devastating reaction to some injections (including vaccines, or any other drug). About 1 in 1000 to 1 in 10,000 cats will develop a very serious cancerous tumor at the injection site. We believe that the adjuvant in the vaccine is a major component of developing these tumors. However, affected cats also seem to have a genetic predisposition to developing this cancer, too. It’s a multi-factor disease that nevertheless is often terminal for the cat. Recombinant, adjuvant-free vaccines are the best way to avoid this complication in cats. We have switched over to the recombinant vaccines whenever possible for the cats in our practice.
Duration of Immunity
This is probably one of the most-asked about aspects of vaccines and immunology. “How long are they good for?” It’s a topic that has been at the center of the most fierce debate between the veterinary community and everyone else. It has also been a source of debate within the veterinary community. I’m going to speak about what we know now, and how Pet Authority has put this knowledge to use.
We know that recombinant vaccines and modified live vaccines are the best ways to develop a good, strong immune response in the safest way possible. We know that -viral- vaccines and recombinant vaccines stimulate a very good longterm (cell-mediated) response in patients. There also tends to be a very strong humoral response that produces a lot of antibodies. We know that puppies and kittens require a series, and then a booster 1 year later, to produce a response that gets both antibodies and cell-mediated immunity to an appropriate level. The question is, what happens after that 1 year booster?
For viral diseases, which are in vaccines like DHPP and FVRCP, the immunity produced lasts longer than 1 year. We no longer vaccinate for distemper annually. After that 1-year booster, we vaccinate every 3 years. It’s widely accepted that nearly all patients will be adequately protected for 3 years and do NOT need to be vaccinated annually for DHPP or FVRCP.
Rabies is a special case because of the public health aspects involved. The FDA and State laws usually determine how often a pet is vaccinated for rabies. Two factors are involved: how long the company says the vaccine is good for, and what the state laws demand for the number of years between vaccines. Dog rabies vaccines have adjuvant and are good for 3 years in almost all cases (so long as the vaccine label says 3 years). The only time you vaccinate more frequently is when laws say you have to. For cats, the vaccine is a recombinant canarypox vaccine, but the label is only good for 1 year. This annual revaccination is less dangerous for cats than giving the adjuvanted 3-year labeled vaccine. We utilize a recombinant feline rabies vaccine for almost every feline patient.
Feline leukemia is also currently an annual vaccine due to manufacturer label. We do utilize a recombinant leukemia vaccine. My hope is that eventually, the company will state their support of a 3-year interval here, too. Theory suggests it should be adequate, but we don’t have the testing to back that just yet.
Bacterial diseases such as leptospirosis and lyme don’t generate a very strong immune response. They’re killed bacteria or parts of bacteria, which doesn’t do a good job of stimulating cell-mediated immunity. Therefore, these vaccines are given annually. The one change we’re making is that for both diseases, a dog can be late by up to 12 months and NOT require a 2-vaccine series to reestablish immunity again. Please keep in mind that if your dog is overdue, it is NOT protected from lepto and lyme! Don’t be late for the vaccines! Bordetella is another vaccine that has to be boostered more frequently due to the killed bordetella portion of the vaccine. We recommend boostering the nasal bordetella vaccine every 6 months for at-risk patients.
Titers are hand and glove with Duration of Immunity. A titer is a measure of the amount of antibody circulating in the bloodstream that matches a particular disease. When we get a ‘distemper titer’ for example, we are measuring how much antibody a dog has in its bloodstream that will fight off distemper virus if the dog is exposed.
I’m of mixed feelings on titers. For some disease (canine distemper and rabies), there is a specific amount of antibody that is considered the minimum for protecting a pet from getting the disease. However, for many other diseases a titer may be misleading. We know that immune responses are composed of two parts: antibody and cell-mediated memory. A LOW titer means a patient has low levels of antibody. However, that patient may still be protected by its cell-mediated immune response. A HIGH titer may not be enough to protect a patient against some diseases. It’s very hard to imply protection from a titer level for most diseases. I don’t recommend titers to our clients unless they -really- want to stretch out those vaccine intervals beyond 3 years. The titers are expensive, may or may not be an accurate measurement of immunity, and the vaccine risks are generally low. I think that putting dogs on a 3-year interval and skipping the titers is the most practical option we have that doesn’t ignore current data.
I think that touches on the majority of the big points of contention in vaccine theory for dogs and cats. If I’ve missed something that you’d like me to comment on or explain, please leave a comment. This is one of my favorite areas of medicine, so I welcome discussion. I hope everyone has enjoyed the holiday weekend!