The Side Effects of a Distemper Shot for Dogs

By Michelle Renee

Canine distemper vaccinations sometimes cause variable side effects in dogs. Not all dogs will experience adverse reactions to essential inoculations, but many will experience side effects regarding the way they feel and behave. Some are mild and of little concern, but if prolonged can be an indication of a more serious problem. Others that are more severe require immediate veterinary attention. It is important for pet owners to be aware of the side effects of distemper vaccinations in dogs.

Anaphylactic Reaction

Immediate veterinary care is required for anaphylactic reactions.

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It is very uncommon for a dog to suffer an anaphylactic reaction to his distemper vaccination. However, if it does happen, there are distinct signs that will occur within minutes or up to 24 hours after the vaccination is administered. Symptoms include vomiting, swelling of the face, diarrhea, seizures and unresponsiveness. These symptoms indicate dire emergency and a veterinarian should be contacted immediately.

Fever and Loss of Appetite

Fever and loss of appetite commonly occur after immunization.

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Many dogs will react to distemper vaccinations by producing a fever with only a slightly elevated body temperature. The fever may be accompanied by a loss of appetite and could last as long as two days. This is a common side effect of canine immunizations and is most often of little concern for the the pet's well being. Unless the condition persists beyond 48 hours, veterinary care is usually unwarranted.


Lethargy is a common side effect of distemper vaccinations.

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For a few days after the inoculations, your dog may seem tired and listless. He may sleep for excessive periods, barely move while awake and appear exhausted when in motion. Lethargy is to be expected because the animal is weak from fighting off the fever and not having eaten. It is quite similar to a human being fighting off the flu. If the dog appears exhausted and depressed, this should quickly pass when the fever subsides.

Swelling at the Injection Site

An abscess at the injection site is of no discomfort to your pet.

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Some dogs will experience a small amount of swelling, and in some cases bruising, at the site of the injection. These minor protrusions are painless and most often dissipate in a short period. Occasionally, dogs will retain the small lump (about the size of a pea) for years with no discomfort. In some cases, it will gradually reduce in size until it no longer exists. The swelling may sometimes be accompanied by a small and temporary loss of hair around the area.