Ask a UW Veterinarian: Antibody Test and Immunization Explainer


This expert response comes from Laurie Larson, veterinarian and director of the Companion Animal Vaccine and Immuno-Diagnostic Service (CAVIDS) Lab at the UW School of Veterinary Medicine.

Question: My breeder insists on titering. Our state, however, requires rabies shots on a yearly or three-year basis. Are you able to shed some insight into this area as to what is best for our dog? — Ann, Roscoe, Illinois

Answer: Thank you for asking about titers. This is a subject of much interest to veterinarians and pet owners. Let’s look at some common questions about this topic.

What is an antibody titer?

Antibody titer (pronounced “tight-er”) represents how many times a serum sample can be diluted and still show the antibody effect of neutralizing specific viruses. In-laboratory tests are functional, demonstrating that an animal’s serum can stop living distemper or parvovirus from interacting with susceptible cells. They are also quantitative, reported as a number.

Submit Your Questions
Have a question for our veterinary medical experts?
Please send them to our On Call magazine editor at We cannot guarantee responses to all submissions. For any urgent pet health issue, please contact your veterinarian directly.

Is titer testing appropriate for all vaccine agents?

The short answer is no. Only vaccines that can induce “sterile immunity” with known thresholds of protection lend themselves to antibody testing. These core vaccines include canine distemper (CDV), parvovirus (CPV-2), infectious hepatitis virus (CAV-1,2), and feline panleukopenia virus (FPV). All puppies and kittens should receive these vaccines.

Why titer test? Why not simply revaccinate an adult pet?

Titer testing is an evidence-based tool to achieve appropriate use of core vaccines by identifying animals that would benefit from vaccination. When the antibody is already above protective thresholds, further vaccination will not make the animal more immune. While the risk of adverse reactions to immunization is small, this risk is not worth taking when there is no benefit to offset it.

What about titers for rabies?

Titer testing for rabies antibody is available outside the UW School of Veterinary Medicine; however, the result cannot be used to determine revaccination. Rabies vaccination is legally required for all dogs in the continental United States, unless a waiver is written for health reasons. If a dog that is overdue for rabies vaccination bites someone, the animal is considered potentially rabid and will be quarantined for observation even with a good titer.

For more information regarding vaccinal antibody titer testing for dogs and cats, please visit the CAVIDS Laboratory website. Thank you for your interest.

This article appeared in the Spring 2021 issue of On Call magazine.

« Back to News