Dog and Cat Vaccines and Titer Testing

By Susan C. Nelson and Susan M. Moore

The number of booster vaccines our pets receive is becoming more commonly discussed amongst both pet owners and veterinarians. Those in opposition of vaccines are passionate about their views, while those in favor of vaccines are equally passionate on the subject. Is one side right and the other wrong, or is there common ground to be found? A little of both. Not all is known about the immune system and much research still needs to be done. Additionally, there is misinformation on the internet, as well as sensationalized stories about pets who may, or may not, have experienced a vaccine reaction.

Vaccines were developed to help prevent infectious disease, and they do. Vaccine technology has advanced tremendously since the inception of vaccinology. Over the years, veterinarians have seen fewer vaccine-related issues than previously reported. Vaccine opponents often argue that ingredients such as adjuvants (aluminum, mercury, formaldehyde and foreign proteins) are often the source of reactions. This was true in the past, however many vaccine have been “purified” over the years, meaning extraneous proteins have been removed. Some of the aforementioned adjuvants have been entirely discontinued in the production of vaccines. This has made them much less reactive for our patients.

What about the flip side of the argument? Can vaccines be harmful for some pets? While adverse reactions to vaccination can occur in many species, the rate of these reactions is low. The risk of not having immunity to common infectious organisms far outweighs the risk of developing serious illness as a result of vaccination.

There are some disease conditions or situations where vaccines may not be in the best interest of a patient. For example, owners of animals that have experienced severe, adverse reactions to vaccines, animals with impaired immunity, and patients undergoing some cancer treatments, should discuss vaccination with their veterinarian. So what can one do if this is the case for their pet?

  • Reassess lifestyle to determine essential vaccines.

  • Allow longer intervals between core vaccine doses after completing an initial series.

  • Separate vaccine administration by at least 3 weeks if an adverse reaction was previously seen when multiple vaccines were given on the same day.

  • Pre-medicate with Benadryl +/- a dose of corticosteroid in the case of more significant reactions.

  • Administer a different brand of vaccine for the next scheduled booster.

  • Check vaccine titer for some diseases to see if the vaccine is necessary.

Vaccine titers have been gaining more acceptance over the past few years to reduce the frequency of vaccination. In order to be useful, two criteria need to be met: 1) One needs to be able to detect a measurable immunity (antibody) to a disease in a blood sample, and 2) There needs to have been challenge studies performed to associate protection with that specific titer level. A challenge study shows that animals which have a specified antibody titer did not get sick when exposed to the disease for which the titer was checked.

Vaccine titers are not an effective means for assessing protection for some diseases. In general, these are for the diseases included in the noncore vaccine category as their specific protective level of antibodies have not been determined. Noncore vaccines are also known as life-style vaccines, and administered based on risk determined by geographic location and activities. For dogs, leptospirosis, Lyme, Bordetella, parainfluenza and canine influenza are risk-based vaccines. For cats, FeLV, Chlamydophila (chlamydia) and Bordetella are administered to cats with greater risk of exposure.

Vaccine titers can be useful for determining the need for DA2P (Canine Distemper, Adenovirus and Parvovirus) and FVRCP (Feline Rhinotracheitis, Calicivirus and Panleukopenia) boosters. These are core vaccines. Every animal should receive core vaccines due to the wide-spread prevalence and severity of the diseases that they prevent. After the pet has completed their initial series of these vaccines and boosters one year later, annual titers can be determined thereafter to assess the need for continued boosters. Many cats and dogs have titers to these diseases lasting many years. In fact, several years ago the AVMA and AAHA recommended increasingthe vaccine interval for DA2P and FVRCP from 1 year to 3 years based on titer testing results.

However, titers have also detected patients that needed their boosters sooner than every 3 years as well, so they are useful in detecting the need for boosters for both animals that don’t need vaccination as well as those that do. Titers are checked by obtaining a blood sample and submitting it for testing. Titer testing can also be considered at the end of the initial series to ensure the patient mounted a protective immune response to the vaccine.

Rabies is a core vaccine and titers can be determined, but the use of titers in lieu of rabies vaccination is not as straight forward. Rabies vaccination is required for dogs (and often cats as well) in most states and/or municipalities as part of rabies control and prevention policies. Rabies is zoonotic (can be transmitted to people) and control in rabies vectors (animals that can carry the virus and infect others) is the most efficient method in prevention human rabies deaths. These laws currently do not include the use of titers in place of vaccination. The other complicating factor is that there is no agreed standard titer value that is considered protective. Not all laboratories that determine titers are accredited and not all test methods are accurate. For a disease that has such great significance with regards to public health, it is important to use a lab that is accredited and has quality control measures in place.

The bottom line is vaccination is safe for the majority of pets and vaccines save many more lives than they harm. What can you do if you are still concerned about over vaccination?

  • Speak with your veterinarian about extending the duration of core vaccines to 3 years as per AAHA, AVMA and NASPHV Compendium of Animal Rabies Prevention and Control guidelines.

  • Consider checking annual titers for FVRCP in cats and DA2P in dogs.

  • Review life style risks for your pet.