Vaccine Allergies in Dogs

An allergic reaction to a vaccine could happen right away, or it could take as long as 48 hours to manifest. Also, allergic reactions are more common with booster shots rather than initial vaccines because the immune system will already have a memory of the disease that the vaccine works against, and could mistakenly react to the vaccine as if it were harmful to the body. 

Symptoms of vaccine allergies include:

• Diarrhea
• Vomiting
• Lethargy
• Swelling or redness at the vaccine site
• Puffiness around the ears, muzzle, and/or eyes
• Bumps or hives all over the body

Although very rare, more severe allergic reactions can occur. These include anaphylactic reactions, collapse, and death. 

Types

There are several different types of allergic reactions that can occur after a vaccine is administered:

• Anaphylaxis - Although rare, this allergic reaction is life threatening and can result in respiratory failure, cardiac failure, shock, and death if left untreated. The reaction could happen within minutes or hours of injection. Common signs include sudden vomiting, diarrhea, seizures, coma, shock, cyanosis, a weak but rapid pulse, and facial swelling.  

• Eye and neurologic disease - Inflammation of the brain or eyes may occur.

•  Reactions at the injection site - Irritation, swelling, pain, and redness can develop at the site of injection, typically anywhere from 30 minutes to a week after the vaccine is given. Abscesses can also form at the site of injection.

•  Respiratory symptoms - A mild cough, sneezing, or discharge from the nose can occur as an allergic reaction to intranasal vaccinations.

• Decreased activity and appetite, as well as depression and mild fever - These symptoms can occur for about one or two days after receiving a vaccine.

If an allergic reaction to a vaccine occurs immediately or a few minutes following administration at your veterinarian’s office, they will be able to provide prompt relief and treatment as soon as symptoms become apparent.

If your dog receives a vaccination and begins exhibiting any of the symptoms associated with an allergic reaction after going home, contact your veterinarian right away, especially if the symptoms are severe.

Usually, your veterinarian will not have to perform any formal tests in order to determine if an allergic reaction to a vaccine is occurring. Instead, clinical signs and examination findings, along with the records of a recent vaccination, will likely be enough information to diagnose the condition in a timely fashion. However, your veterinarian may want to do a complete blood count, urinalysis, and fecal analysis in order to determine if any organ systems in the body have been adversely affected. These diagnostic tools can also determine if your pet has an underlying illness that may have caused a vaccine reaction.

Treatment for vaccine allergies in dogs will depend upon the level of allergic reaction and the type of vaccine that was administered. Your veterinarian will determine what the appropriate treatment will be after thoroughly examining your dog. 

If your pet is experiencing a mild reaction to the vaccine such as redness around the injection site, the veterinarian may administer an antihistamine or an injection of  cortisone to reduce the swelling. If there is vomiting, the veterinary team may monitor your dog for an additional time before allowing you to take your dog home.

In the case of an anaphylactic reaction, your dog may have to be admitted to the clinic for intravenous therapy or additional medical intervention such as oxygen support or epinephrine. Once the veterinarian feels he is out of danger, your pet will be allowed to go home. The veterinarian may recommend you monitor your pet at home for the next several hours to few days.