Vaccines, as I have mentioned many times on this blog, are perennially controversial. Many people worry that pets are vaccinated too often. Experts voice concerns that over vaccination may lead to autoimmune disease. Leukemia and rabies vaccines in cats have been linked to cancers at the injection sites.

The obvious goal for every veterinarian and conscientious pet owner should be to vaccinate pets neither too frequently nor too rarely. In an ideal world, we would vaccinate pets exactly as often as necessary. I predict that in the future this will be the norm. But as of 2009, it is impossible to say how often pets need vaccinations.

Some facts are clear. Juveniles (puppies and kittens) need vaccines more often than adults. Animals with different lifestyles need different vaccination protocols. And most important, every individual responds differently to vaccines. Every individual therefore has unique needs.

Measuring those needs is impossible. Blood tests called titers give some idea of a pet’s response to previous vaccinations, but titers measure only half of the picture. Titers measure antibody levels in the blood. However, antibodies cannot function without another component of the immune system called cell-mediated immunity. At this time there is no way to measure cell-mediated immunity. Therefore there is no way to measure a pet’s true level of immunity to disease.

I agree that many pets are vaccinated more often than necessary. On several instances I have treated animals for autoimmune disease and wondered whether vaccines might have contributed to the problem.

However, on hundreds of instances I have treated canine parvovirus. In every single one of these cases I knew with certainty that vaccination would have prevented the problem. I never have treated a properly vaccinated dog for parvo. The vaccine works.

I euthanized a 12-week-old puppy today because of parvo. A vaccine could have saved his life if it had been administered at the right time.

Over vaccination is a bad thing. Veterinarians and pet owners should work to prevent it. But don’t forget that under vaccination is even worse.

Your best option as a pet owner is to find a good vet who will take the time to discuss the controversies surrounding vaccines. Tailor a vaccination protocol to your pet based upon his or her needs, age, and lifestyle.

Share this entry with your pawple anywhere:

• Are Pets Being Over-Vaccinated?
• Where do Vaccine-Associated Tumors Develop in Cats?
• DVM Newsmagazine: Rabies Rate in Cats Four Times That in Dogs
• Why Aren’t Titers Used in Lieu of Vaccines?
• What are the Rationales Behind Rabies Vaccine Schedules?

Dr Barchas,

Randy
San Diego

A minimal vaccination schedule depends upon a dog’s age and lifestyle. In a mature dog, a minimal vaccination schedule would mean avoiding optional injections such as the ones that protect against Bordetella, canine coronavirus, and probably leptospirosis (but talk to your vet about this one first–leptospirosis can spread to humans). Mature dogs generally need vaccines no more often than once every three years. In some cases it may be safe to push vaccines other than rabies (see my previous post) back to once every five years or longer. You will have to find a vet who will take the time to work with you to tailor a vaccine schedule that is appropriate for your dog.

Titers are blood tests that are performed to assess immunity. Titers measure a component of the immune system called antibodies that circulate in the blood. They are reported as a ratio of one to a number. The higher that number, the better. A titer of 1:5 is low. A titer of 1:1,000,000 is very high.

Your vet may have been concerned about using your dog’s titers because the titers were low. Or, he may have been concerned by something else: nobody knows how to interpret titers. I am not aware of any studies that show what titer is required to prevent infection with rabies, distemper, or parvovirus. A low titer likely implies susceptibility to disease and a high titer likely implies immunity.

However, we do not know the most crucial piece of information that is necessary for interpreting titers. We do not know the minimum titer measurement that correlates with protection from disease.

There is another factor that complicates the use of titers. Titers measure only half of the immune system. Although it is very useful to know the quantity of antibodies circulating in the bloodstream, antibodies cannot work alone. They depend upon a different portion of the immune system (called cell-mediated immunity) to get the job done. At this time, I am not aware of any way to test cell-mediated immunity.

Consider this analogy. Antibodies are like foot soldiers in the battle against disease. Cell-mediated immunity represents logistics and weaponry. If your dog has a high titer against rabies, that is the equivalent to having a huge army of soldiers ready to battle the disease. But it matters whether the soldiers are armed with high caliber weapons and advanced communications, or whether they are disorganized and can fight only by throwing dirt clods.

Without the ability to measure cell-mediated immunity, one cannot truly know whether a pet is protected against the disease in question.

In general, high titers likely are correlated to strong cell-mediated immunity. I strongly believe that in the future either titers or other tests of immunity will supplant regular vaccinations in pets. I am confident (perhaps optimistic would be a better word) that in the next half decade we will see some major advances in immunology that will lead to decreased animal vaccinations and increased use of immunological assays.

But for now, although titers provide significant information, they do not look set to revolutionize veterinary medicine.

Photo: Jeffrey M. Vinocur

Share this entry with your pawple anywhere:

• Are Pets Being Over-Vaccinated?
• Despite Controversy There is no Doubt That Vaccines Save Lives
• Does Pet Food Cause Health Problems?
• DVM Newsmagazine: Rabies Rate in Cats Four Times That in Dogs
• How Much and How Often Should I Feed my Dog?

How SAFE are vaccinations? Are we over
vaccinating our dogs?

Jade
Chicago, IL

Animal vaccination is a perennially timely and controversial subject. The short answer, Jade, is that nobody knows how often pets should receive vaccines. Nobody knows whether pets need vaccines every year (although they probably don’t).

Although titers probably will be widely used in the future, they aren’t common now for two reasons. First, nobody truly knows how to interpret them (that is to say, nobody knows what titer level is protective for each disease). Second, titers measure only half of the immune system (a portion called humoral immunity) and ignore the other half (called cell-mediated immunity).

I have covered the subject of animal vaccines a few times on this blog. Click here, here, here or here for more information.

A very bad experience from the other night reminded me of a stark truth. Although giving too many vaccines may cause health problems for some pets, giving too few vaccines is virtually guaranteed to lead to sick pets.

I was working at an emergency hospital when a family brought a six-month-old Poodle to my office. The Poodle had a 12 hour history of poor appetite, vomiting, and diarrhea. He had never been vaccinated.

A test of his stool revealed that he was infected with parvovirus. Untreated parvovirus is a deadly disease. Parvovirus is preventable with vaccines. If that puppy had been properly vaccinated, he would not have caught the disease.

To make matters worse, the family had another unvaccinated puppy at home. I explained to them that their other puppy would almost certainly catch the disease. And then they revealed that, three months ago, the family had lost a third (unvaccinated) dog to parvo.

This means that, in the course of a single appointment, I became aware of two puppies who needlessly suffered from a preventable disease because of lack of vaccination. A third puppy is almost certain to become ill and possibly die because of the family’s irresponsibility.

Although over-vaccination is not an optimal scenario for pets, please remember that it is better than the other extreme. If you don’t vaccinate your pets at all, you are asking for them to get sick.

Share this entry with your pawple anywhere:

• Despite Controversy There is no Doubt That Vaccines Save Lives
• How Much and How Often Should I Feed my Dog?
• Why do Puppies and Kittens Produce so Much Waste?
• Why Aren’t Titers Used in Lieu of Vaccines?
• Don’t Take Vaccine Advice From Activists