I’m a big fan of vaccinating pets. Immunization has successfully prevented disease in millions of pets for years. But once in a while, a vaccine doesn’t work for a particular animal.
Vaccine failure is pretty rare, but it can happen. Here are a few reasons why:
- Different strains of the same disease. Most of the time, the strain of a disease used in a vaccine protects your pet against other strains of the same disease. Sometimes, a new strain evolves that is resistant to the vaccine. (Drug-resistant diseases are a problem for humans, too.)
- The vaccine was spoiled. Many vaccines are sensitive to light and temperature — if the vaccine isn’t refrigerated in transit, it may no longer be effective on arrival. Veterinarians routinely refuse shipment of vaccines if the medication is warm when it is delivered. Inexperienced workers may accidentally spoil vaccines, which is why it may be safest to get your pets’ immunizations from a veterinarian.
- The pet was already exposed to the disease before receiving the vaccine. Many diseases have an incubation period, where a pet shows no symptoms but is already infected. A vaccine given during the incubation period may too late to prevent illness.
- The pet is unable to produce antibodies after vaccination. A pet with chronic health issues, malnutrition, or stress may have trouble developing immunity to a disease after receiving a vaccine. Some pets are born with immune system issues.
- Interference from maternal antibodies. Nursing animals get antibodies from drinking mother’s milk — this is called passive immunity. An immune system that produces its own antibodies is called active immunity. High levels of antibodies from the mother can prevent a baby from developing active immunity after a vaccination.
For the most part, vaccines for pets work well to prevent disease. Talk to your veterinarian about the immunizations that are suggested for your pet.