Allergic Reactions in Dogs

Allergic reactions in dogs may occur due to a number of allergens, insect bites or vaccines. The allergic reactions in canines may be urticaria, angiodema or anaphylaxis.

Urticaria is a reaction on the skin that doesn't necessarily need treatment, while anaphylaxis is more serious and may be fatal. It is important to recognize the signs of allergic reactions, so as to be able to apply treatment and help your pet in a timely manner.

Urticaria and Angiodema

Dogs may display skin allergic reactions to medication, vaccines, pollens, dust, bites, food or even sunlight.

The allergic reactions may be:

  • Urticaria, also known as hives: Appears as small bumps on the surface of the skin. In some cases, the bumps are itchy.
  • Angiodema: The dog's face will be swollen. The swelling may be light or severe, depending on your dog; the condition causes itchiness.

Both allergic reactions will occur within 15 to 20 minutes after the exposure to the allergen. Typically, these reactions will go away without treatment and are not severe.

In rare cases, angiodema may affect breathing if the throat is swollen. If the swelling is serious, the dog will be unable to open his eyes.

If these allergic reactions are severe, antihistamines are recommended. In rare cases, steroids are prescribed. If angiodema affects the throat, a shot of epinephrine is necessary to reduce the swelling.

These reactions can be prevented only if you are aware that your dog is allergic to vaccines or certain chemicals. The dog needs to be less exposed to the allergens.

In case your dog is allergic to injections or vaccines and these are necessary, the vet will prevent the allergic reactions by administering antihistamines prior to vaccination.

The vet may also recommend an epi-pen for emergencies, which is a syringe with a dose of epinephrine.


Anaphylaxis is a severe allergic reaction. It may cause shock, respiratory failure or cardiac arrest and can be fatal if not treated.

Anaphylaxis may be due to:

  • Insect bites
  • Antibiotics
  • Vaccines
  • Drugs
  • Food ingredients
  • Toxic plants or foods for dogs

Anaphylaxis will be signaled by sudden diarrhea, vomiting, pale gums, cold limbs, fast heart rate, weak pulse, seizures and shock. The dog may enter a coma.

If the dog suffers from an anaphylactic shock he needs a shot of epinephrine immediately. If epinephrine is not administered within a few minutes after the onset of the symptoms, the dog may die. After the shot, the dog will also need oxygen and IV fluids. Further medication may be prescribed.

If you know that your dog may develop an anaphylactic reaction, you need to avoid the allergens and keep an epi-pen at hand at all times. Make sure you know how to use the epi-pen, as this may save your dog's life. After administering the epinephrine, take your dog to the vet as he may need additional assistance.

Epi-pens are available with prescription.