DHPP or DA2PP Vaccine for Dogs

DHPP Vaccine for Dogs
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Most dog owners have heard about the DHPP (or DA2PP) vaccine. This is one of several important immunizations recommended by veterinarians for most dogs.

What Is the DHPP vaccine?

DHPP, also called DA2PP, is a combination vaccine that immunizes dogs for four diseases. The vaccine is typically injected subcutaneously (under the skin). Each letter in DA2PP or DHPP stands for one of the diseases covered in the vaccine. DA2PP vaccines are modified live vaccines (MLV). They contain a small amount of the virus in order to "teach" the immune system how to fight it. The amount of virus present is not capable of making a dog become clinically ill with the virus.


Canine Distemper is a serious virus that starts in the respiratory system. In addition to respiratory signs, distemper can cause thickening of nose and foot pads, fever, and gastrointestinal problems. This disease is highly contagious to unvaccinated dogs and is often fatal.

Adenovirus Type 2 or Hepatitis

Canine Adenovirus type 2 was formerly called hepatitis but does not refer to the type that is contagious to humans. This virus may cause kennel cough in dogs, but the vaccine is mainly intended to protect against canine infectious hepatitis virus caused by CAV-1. The vaccine also protects against CAV-2, which is associated with canine infectious respiratory disease syndrome.


Parvovirus is a highly contagious, life-threatening virus that causes severe gastrointestinal effects in dogs. Humans cannot contract parvovirus, but the disease can easily pass from dog to dog via clothing and objects. Parvo can be fatal, especially in puppies.


Parainfluenza is a virus that affects the respiratory system in dogs and is known to cause kennel cough. Signs include coughing, nasal congestion and discharge, fever, lethargy, and loss of appetite.

Is the DHPP Vaccine Important for Dogs?

Distemper, adenovirus type 2, and parvovirus are all considered core vaccines by the American Veterinary Medical Association and American Animal Hospital Association. This means they are recommended for all healthy dogs, regardless of lifestyle or environment. Most manufacturers combine these vaccines and include parainfluenza. Parainfluenza is not considered a core vaccine, but many vets prefer to include it in the combination of vaccines administered to dogs.

How Often Should Dogs Get the DHPP Vaccine?

The AVMA has established standards regarding the DA2PP vaccine.

  • Puppies under 16 weeks old: Vaccinate as early as six weeks of age, then booster every two to four weeks until the age of 16 weeks.
  • Dogs over 16 weeks old with no vaccine history: Vaccinate, then booster one time within two to four weeks.
  • Adult Dogs: Vaccinate one year after the initial vaccination series, then booster every three years.

Possible Side Effects of the DHPP Vaccine

All vaccines have potential side effects, but veterinarians agree that the benefits of vaccines outweigh the risks for most dogs. Most vaccines have self-limiting effects. They may cause lethargy, decreased appetite, and mild pain and/or lumps at the site of injection. These side effects typically resolve within a day or two.

Vaccines should not be administered to a dog with a fever. In general, sick dogs should not be vaccinated until they have recovered from illness. Vaccines are generally avoided in any dog with a history of autoimmune diseases because it may cause the dog to become sick.

Vaccine Reactions

Vaccine reactions are uncommon and typically occur within 15-30 minutes of injection. Signs of vaccine reaction may include vomiting, diarrhea, seizures, difficulty breathing, facial swelling, and collapse. Bring your dog back to the vet immediately if you notice any of these signs.

Long-Term Effects of Vaccines

There is little evidence about the potential long-term effects of the DA2PP vaccine in dogs. In general, overvaccination has been associated with an increased risk of autoimmune disease in dogs. However, modern vaccine protocols strive to reduce overvaccination. The vast majority of dogs experience no long-term effects from immunizations.

Can Dog Owners Decline the DHPP Vaccine?

Vaccines have been the subject of controversy on both the human and veterinary sides. Most experts agree that the DHPP is an important part of keeping dogs healthy and recommend that all healthy dogs receive the DA2PP vaccine. However, this vaccine is not required by law in the United States (unlike the rabies vaccine, which is legally required in all 50 states).

Owners may choose to decline the DA2PP vaccine, but this puts all dogs at risk because one sick dog can spread disease to numerous other dogs. If you choose not to vaccinate your dog, then you might not be permitted to take your dog to grooming facilities, boarding facilities, dog daycare, dog parks, and other places where dogs gather. In general, you should not allow your unvaccinated dog to come into contact with other dogs, especially those that are sick or unvaccinated.

It is up to pet owners to do research and find veterinarians they can trust, then make a decision that is best for the health of their dogs. Responsible dog owners will consider the health of other dogs when making decisions about vaccines for their own dogs.

Article Sources
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  1. Vaccination Recommendations for General Practice.” Aaha.Org, https://www.aaha.org/aaha-guidelines/vaccination-canine-configuration/vaccination-recommendations-for-general-practice/. Accessed 1 Aug. 2021

  2. Gershwin, Laurel J. “Adverse Reactions to Vaccination.” The Veterinary Clinics of North America. Small Animal Practice, vol. 48, no. 2, 2018, pp. 279–290