Should we vaccinate parvo or distemper positive dogs & how long does vaccination take until it protects?


I work for animal control.  We do not have a place to isolate animals from the population. In regards to vaccinating animals upon impound, if the animal already has distemper, parvo, etc... if we give them the MLV 7 in 1 vaccine, does this increase the disease in the animal and make it more prevalent to shedding the disease to the rest of the population? And if given the vaccine upon intake and held for are standard 5 days, does this give enough time for animals to build an immunity to it while in our shelter?


Thank you for your questions regarding vaccination and disease control. I am glad to hear that you are vaccinating animals upon impound, or at least considering it. This is an extremely important component of protecting the health of the animals in your shelter.

If a dog arrives at the shelter already infected with parvo or distemper, vaccinating them is unlikely to have much of an impact. It will NOT make them sicker, and it will NOT increase the risk they will shed the infective virus. In rare cases, a vaccine given very soon after infection may actually even have some protective effect, but this does not mean that vaccination should be considered as part of "treatment" for parvo or distemper. It just means that ALL dogs arriving at the shelter should be vaccinated, even if they are already sick. The only exceptions should be animals that are so sick or injured that will be immediately euthanized, or animals that are too aggressive to be safely vaccinated.

In most shelters, and especially in shelters without adequate isolation facilities, dogs are more likely to be exposed to parvo or distemper IN the shelter than they are to arrive at the shelter already infected. So, the best rule of thumb to follow it to vaccinate ALL dogs (and all puppies 4 weeks of age and older) immediately on intake with a modified-live DHPP vaccine. The DHPP vaccine is also sometimes called a DAPP or a DA2PP.

Note that the DHPP (or DAPP or DA2PP) is is a 4-way vaccine, not a 7-in-1 vaccine. This is the only injectable vaccine that is recommended at intake for shelter dogs. It includes only the 4 diseases that are MOST important to protect shelter dogs and puppies against - distemper (D), adenovirus-2 (A2, also called canine infectious hepatitis virus, H), parainfluenza (P) and parvo (P). 7 in 1 vaccines include additional components, such as corona virus and leptospirosis. These additional components are not recommended for shelters - they significantly increase both the cost and the risk of adverse reactions of the vaccines. So, use a DHPP instead of a 7-in-1 vaccine.

The time it takes for immunity to develop after vaccination varies with the different vaccine components. Vaccines for canine distemper have been shown to provide very good protection, even when given only 15 minutes before exposure to the disease! The parvo part of the vaccine takes a bit longer to work, but certainly, dogs can develop significant immunity within 5 days of a modified live vaccine.

Most shelters, even government facilities with very little funding, generally find that they would like to house at least some highly adoptable dogs for a bit longer than the required holding period in order to give them an opportunity to be adopted into a new home. Other government facilities develop partnerships with private humane societies, in which highly adoptable animals are transferred to the private facility for adoption. Of course, the extent to which this is possible depends on many factors, such as capacity of your facility, staffing levels, the number of potential adopters visiting the shelter, and the presence of any agencies willing to transfer dogs from your area. However, if adoption or transfer is a possibility for some dogs, ensuring the health of these adoption or transfer candidates is extremely important. Shelters are generally very high-risk environments for disease exposure, especially shelters without adequate isolation facilities. Vaccination of all animals on intake is one of the simplest and most cost-effective tools available to help protect the health of all shelter animals, especially those with adoption potential.

For more information, please see our Information Sheet on Vaccination. Also, you may find the following previously answered FAQs helpful:
#585, #551, and #132.