Insect Bite Reaction in Dogs

By Ryan Llera, BSc, DVM; Tammy Hunter, DVM; Ernest Ward, DVM

What causes a reaction to an insect bite?bee dog nose

Many people and pets are sensitive to the proteins in the saliva or venom of biting insects. They may be born with certain sensitivities or, more often, they may develop sensitivities if exposed numerous times to a particular insect bite. Bee stings and bites from spiders, fleas, and ticks are the most common causes of insect bite reactions in pets.

What are the clinical signs of an insect bite reaction?

The most common clinical signs associated with an insect bite reaction include:

  • swelling and redness at the site of the bite
  • hives or multiple red, raised swellings over the body
  • a swollen face or muzzle
  • difficulty breathing and vomiting

Some patients will progress to severe respiratory distress and anaphylactic shock.

How is an insect bite reaction diagnosed?

Diagnosis is based on clinical signs and a history of the pet who was stung or bitten. In certain cases, blood samples will be analyzed for eosinophils (the white blood cell associated with many allergic reactions).

How is an insect bite reaction treated?

Treatment is based on the type of insect bite, the number of bites, and the severity of clinical signs. Treatment typically consists of removing the stinger or other insect parts and administering antihistamines, such as diphenhydramine, cetirizine, or loratadine, and anti-inflammatory agents, such as corticosteroids, such as dexamethasone or prednisone, as needed.

Supportive measures such as intravenous fluids, corticosteroids, oxygen therapy, and epinephrine (adrenaline) are often required in patients who progress to systemic or anaphylactic shock. In these severe cases, electrolyte levels will be monitored, and a urinalysis will be performed to evaluate urine output and kidney function.

What is the prognosis for insect bite reactions?dog_insect_bites_2018-01

Except in rare cases of anaphylactic shock, the prognosis is excellent. Cases that involve tens to hundreds of bee stings merit a more guarded prognosis.

Future insect bites should be avoided because many reactions worsen with repeated exposure to the offending proteins or toxins. You should always tell your veterinarian if your pet has ever experienced an insect bite reaction so preventive measures can be taken in the future. Many pets that demonstrate insect bite hypersensitivity are also hypersensitive to flea and tick bites, pollens and molds, and many foods. Consult your veterinarian about safe and effective products for preventing insect bites in your dog.

See the handouts “Flea Allergy Dermatitis in Dogs” and “Spider Bites” for more information about these topics.

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