Benadryl to Treat Dog Allergies

Allergies are a common problem in dogs, which respond to allergens primarily with skin problems. A dog suffering from allergies may have a poor quality coat, itchy spots, uncomfortable areas on the skin or even torn skin from scratching and biting. According to K9 Web, allergies may also contribute to chronic ear infections. Since allergens cause the body to release histamine, antihistamines such as Benadryl are commonly used for treatment.

  1. Significance

    • According to Pet Place, Benadryl is officially registered for use in humans only. Benadryl is actually the brand name of a common human formulation. Many generic preparations of this drug, called diphenhydramine, are also available. Despite not being registered for veterinary use, this drug is the most commonly used antihistamine for dogs, according to Nelson Animal Hospital. Prescription of Benadryl for extra-label use is entirely legal.

    Function

    • Histamine is released in response to an allergen or other inflammation. Once the chemical attaches to histamine receptors, it causes itchiness, swelling and other allergic symptoms. Benadryl works by preventing histamine from binding to the receptors, particularly H1 receptors, which affect the smooth muscles and small blood vessels.

    Safety

    • Benadryl is normally safe and effective in dogs, but according to Pet Place, should never be administered without the guidance of a veterinarian. Some animals may have an allergy or hypersensitivity to this drug. Benadryl may also be dangerous in dogs suffering from overactive thyroid, heart disease or high blood pressure, lung disease or glaucoma. It should not be taken with tranquilizers, barbiturates, heparin or epinephrine.

    Side Effects

    • Even when used safely to treat allergies, Benadryl may cause dogs to suffer some side effects. The most common include a lack of appetite, vomiting, diarrhea and lethargy. According to Nelson Animal Hospital, it may take up to 14 days of use to determine whether Benadryl is effective--owners should not discontinue use simply because of side effects unless they are severe.

    Considerations

    • Benadryl may appear not to work in dogs due to excessively low dosage. According to K9 Web, most owners give their dogs too little of an antihistamine to treat the allergic reaction. According to Pet Place, dogs should receive 0.5 to 2 mg of oral Benadryl two to three times a day, or 0.5 to 1 mg per pound subcutaneously, intramuscularly or intravenously twice per day.