What Are the Side Effects of the Distemper Vaccine in Dogs? · Kinship

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What Are the Side Effects of the Distemper Vaccine in Dogs?

Know what to look for.

by Dr. Alycia Washington, DVM, MS
March 17, 2025
Woman comforting her small brown dog at home.
New Africa / Shutterstock

In This Article:

What Is Distemper Virus in Dogs? What Is Distemper Vaccine in Dogs? When Should Dogs Receive the Distemper Vaccine? Distemper Vaccine Side Effects in Dogs When To See a Vet About Vaccine Side Effects

You’re at your vet’s office for your dogs vaccine appointment, which includes receiving the distemper vaccine. After your pup gets routine vaccinations, the staff asks you to hang out in the exam room for a few minutes to make sure your dog doesn’t have a reaction. Even after checkout, they give you a list of symptoms to watch out for — just in case.

Now, you’re at home staring at your dog and wondering: Could my dog have a reaction? Is the distemper vaccine in dogs safe? Should I even vaccinate for distemper? 

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The answer is: Yes, absolutely. Let’s talk about why.

What is distemper virus in dogs?

Canine distemper is a highly contagious viral infection that can affect dogs, ferrets, and certain wildlife species, though young and unvaccinated dogs are at highest risk for severe disease. The virus is typically spread via airborne particles after infected dogs cough, sneeze, or have nasal discharge; but it can also spread via other bodily fluids. 

Dogs infected with the distemper virus can have symptoms stemming from their gastrointestinal tract, respiratory tract, and neurological system. There is no cure for canine distemper. Some dogs can recover with supportive care, but the disease is often fatal.

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What is the distemper vaccine in dogs?

Vaccinations are often the best defense that we have against some of the most harmful diseases in dogs. For some diseases, like rabies, vaccination is the best way to protect both dogs and humans against diseases that have limited treatment options and a high mortality rate. 

The distemper vaccine is no different. It’s the best defense we have against canine distemper virus. It’s considered a “ core vaccine,” which means it’s recommended for all dogs regardless of location or lifestyle. 

The distemper vaccine is typically part of a combination vaccine that also protects dogs against other diseases. The benefit of these combo products is fewer shots, which can result in lower risk for vaccine reaction. The combo vaccine is often referred to as DHPP, DA2PP, or a five-in-one vaccine. These vaccines protect dogs against:

Some vaccines (DHLPP or DAPP/L4) will also include protection against leptospirosis. 

When should dogs receive the distemper vaccine? 

According to the American Association of Animal Hospital’s (AAHA) most recent vaccination guidelines, puppies can receive their first distemper shot as early as six weeks of age. Puppies should receive booster shots every two to four weeks until they’re at least 16 weeks old. The reason for repeat vaccinations early in life is to ensure protection as the passive immunity gained from their mom gradually fades. 

After the initial vaccination series, dogs should receive a booster one year later, and then another every one to three years for life. 

Distemper vaccine side effects in dogs

Although vaccines are generally safe, reaction to distemper vaccine in dogs is possible. Most side effects are mild, show up soon after the vaccine is given, and resolve on their own, but others can be delayed, severe, and require medical intervention. Here are possible side effects of the distemper vaccine: 

Common side effects

Fatigue

Vaccination stimulates the immune system, which can have an effect on a dog’s demeanor. Like other immunizations, the distemper vaccine in dogs often causes dogs to have less energy, reduced appetite, and sometimes a low-grade fever. These symptoms should pass after a day of rest. 

Swelling or pain at the injection site

Mild swelling and a little tenderness at the injection site can be expected after vaccination. A dog should not be in a lot of pain, and the discomfort should go away within a day or so. Swelling at the vaccination site can linger a bit longer (a couple weeks) but should not grow in size. If you notice swelling that is growing, painful, or starting to ooze, have your vet evaluate this to make sure an abscess isn’t developing at the site. 

Uncommon (but possible) side effects

Hypersensitivity/allergic reactions

Allergic reactions to distemper vaccines can occur within minutes of administration; that’s why your vet staff may ask you to sit for a few minutes after the injection to make sure your pup doesn’t start showing symptoms. But you can also see reactions up to 12 hours later, so it’s important to monitor your pup at home.

Allergic reactions to distemper vaccines in dogs can range from mild to severe and often involve facial swelling, itching, and hives. Dogs having severe allergic reactions can develop acute vomiting, diarrhea, weakness, breathing changes, and collapse. In cases of severe allergic reaction, or anaphylaxis, aggressive treatment is needed ASAP to address the effects the reaction is having on the body. 

Rare side effects

Autoimmune hemolytic anemia

Immune-mediated hemolytic anemia (IMHA) is a condition in which the body attacks and destroys its own red blood cells. Most cases of IMHA in dogs are idiopathic, meaning there’s no known cause, but IMHA can be triggered by other issues such as infection and cancer. While it has yet to be proven, vaccines (including the distemper vaccine) have been suspected of being a possible trigger for IMHA in dogs. 

Hypertrophic osteodystrophy

Hypertrophic osteodystrophy (HOD) is a condition that causes inflammation at the growth plates of the bones of growing puppies. Large-breed puppies are most susceptible to HOD. The condition has also been reported to have developed in puppies infected with the distemper virus. There is also a report of HOD developing in Weimaraner puppies about ten days after receiving a distemper vaccine. 

Post-vaccinal encephalitis

You can file this one away under super rare: There have been reports of encephalitis (inflammation of the brain) after distemper vaccine administration in dogs. This is similar to the neurological changes seen with actual distemper infections. One case study describes two dogs from the same litter developing the neurological condition one year apart, suggesting a possible genetic component to this vaccine reaction.

Juvenile cellulitis

Juvenile cellulitis, commonly called “puppy strangles,” is a condition in young puppies that causes facial swelling, enlarged lymph nodes, and the development of several raised bumps on the head and face. The condition is uncommon and may be caused by disruption of the immune system, and distemper vaccines have been thought to be a trigger in rare cases.  

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When to see a vet about vaccine side effects

If your dog is a little tired and sore after a vaccine appointment, it’s OK to wait it out and monitor them at home. However, they should be seen by a vet as soon as possible if they develop any of these more severe symptoms:

  • Facial swelling 

  • Hives

  • Vomiting

  • Diarrhea

  • Breathing changes

  • Weakness

  • Collapse

If your dog has experienced any of these symptoms in the past (even after a separate vaccine), be sure to inform your veterinarian before future vaccine appointments.

Bottom line

Adverse reactions to the distemper vaccine in dogs can vary from mild to severe, though severe reactions are rare. Despite the potential for vaccine side effects, all dogs should be vaccinated against the distemper virus. There is no cure for distemper, and the mortality rate is high, especially for dogs who are young or who develop neurological symptoms. Although some of the potential distemper vaccine side effects can sound pretty scary, vaccines are generally safe for dogs, and the benefit of disease prevention far outweighs the risk of a reaction. 

References

alycia washington, dvm

Dr. Alycia Washington, DVM, MS

Alycia Washington, DVM, is a small animal emergency veterinarian based in North Carolina. She works as a relief veterinarian and provides services to numerous emergency and specialty hospitals. Dr. Washington is also a children’s book author and freelance writer with a focus on veterinary medicine. She has a special fondness for turtles, honey bees, and penguins — none of which she treats. In her free time, Dr. Washington enjoys travel, good food, and good enough coffee. 

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