Vaccinations are a critical piece of shelter operations to minimize disease transmission and keep shelter populations healthy. Many vaccinations can protect against disease within hours. Some vaccines actually prevent disease, while others reduce the severity of disease. Because we often do not know the vaccination history of animals entering shelters and the risk of exposure is often greater than in a typical home setting, vaccination remains an essential part of the intake process.
Within a shelter population, there will always be risk of disease due to animals arriving without proper immunity. One of the best ways to protect against infectious diseases is to follow vaccination schedules for shelter animals that generally begin at a younger age and include more frequent re-vaccination. These recommendations also include vaccinating virtually all animals at or prior to intake to help ensure protection for individual animals as well as a higher level of herd immunity in the shelter population. This process can help to contain any disease to one or few animals and reduce the overall risk of a disease because a high percentage of the population will be protected through vaccination.
Most vaccines recommended for use in shelters contain living organisms. It is very important to have proper storage, handling, and administration to ensure the organisms remain viable and able to induce a protective immune response.
Vaccination is a medical procedure, so oversight of vaccine protocols must be directed by a veterinarian. Vaccine administration for every animal at or before intake is a critical practice in minimizing infectious disease and preventing widespread outbreaks. Modified live vaccinations (MLV) are strongly recommended over killed or inactivated vaccinations. Most animals will respond to a single MLV vaccine very quickly: in as little as 24 hours for canine distemper or 72 hours for canine parvovirus or panleukopenia. When killed products are used, there is a significant delay in the onset of protective immunity. In addition, MLV vaccines are better able to override maternal antibody interference in puppies and kittens.
Kittens and puppies need frequent core vaccines due to maternal antibodies, which can inhibit vaccine effectiveness in a process called maternal antibody interference. These are protective immune molecules that are transferred from mothers and protect young animals while their immune system is maturing. Some antibodies cross the placenta, but the majority are obtained during early nursing. The amount of maternal antibodies passed onto a kitten or puppy can be quite variable due to things like the mother’s vaccine history and prior natural exposure to disease. These antibodies only provide temporary protection, however, as their levels decline over time.
In shelter medicine, a practical strategy used to overcome the interference of maternal antibodies is to begin vaccinating as early as possible, which is approximately 4 weeks of age. Because we don’t know when the maternal antibodies will decrease enough to allow the vaccine to be effective, we continue to vaccinate at frequent intervals until we can be sure there are no maternal antibodies remaining. This is typically every 2-3 weeks until 20 weeks of age to minimize the “window of susceptibility”, the time when maternal antibody levels aren’t sufficient to protect against disease but can still block the young animal’s own immune response. The key concept is not that a certain number of vaccines are administered per kitten or puppy, but the vaccines are given at appropriate intervals until the animal has reached an age when maternal antibody interference is no longer a concern, typically at 5 months of age.
Core vaccinations for dogs include:
Core vaccinations for cats include:
Learn vaccine recommendations for shelter dogs and shelter cats.
Vaccinating can be a lifesaving procedure, but it is a medical intervention that is not without risks. Many animals in shelters have not had natural or vaccine exposure to common diseases, so the benefit of immediately vaccinating every animal over 4 weeks of age on intake typically outweighs the risks. In general, the recommendation is that every animal housed in a shelter is vaccinated with core vaccinations except in extraordinary circumstances.
Below are guidelines to help shelter personnel make decisions about vaccinating individual animals with specific conditions. When making difficult vaccination decisions, it's best to consult the veterinarian your shelter works with and consider the overall benefit and risk to each individual animal as well as the shelter population as a whole.
See this Vaccination Decision Table for a quick view.
