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Antihistamines for Dogs

Antihistamines for Dogs

Animal anatomy is different from humans, nevertheless, our faithful pets can catch infections and become unwell, just as we do. Choosing the right antihistamine for dogs can be a tricky process, as you never know how your dog's body would react to it. Take a look at some commonly used antihistamines for multiple breeds, which are suggested by a number of vets!
DogAppy Staff
Canines have been generally found to contract allergies between one and three years of age, and sometimes, also during the later years. They can be allergic to pollens, food products and house fleas. Most of the allergens are airborne and enter the dog's body through inhalation. However, the allergic reaction can be severe only if your dog has had prolonged exposure. Once the allergens are inside, they disturb the immune system by adhering to certain tissue mast cells in the skin. This may results in the release of chemicals, including histamine.
This particular chemical - histamine, has degenerating effects on the immunity of dogs, and cause:
  • swelling in various organs
  • redness of skin
  • blood pressure changes
  • loss of appetite
  • pain
  • vomiting
  • acidity
Antihistamines reduce this allergic reaction and strengthen the immune system to fight against the allergens. There are various antihistamines for each individual breed of dog, but there are a few which can be commonly used for all breeds.
If your dog has an allergic reaction, visit your veterinarian for advice and medication. The most popular antihistamine is Diphenhydramine. It can be given to a dog of any breed, but it should be used according to prescription and in proper dosage. Few antihistamines have been listed here, along with the dosage. The list is only for reference, and any medication must be administered as prescribed by your veterinarian.
Over-the-counter Drugs
Diphenhydramine
It is available in the market in 25 mg capsules and 12.5 mg tablets (for children). It is also available in the liquid form, but is generally not recommended, as it contains alcohol. Also avoid using Diphenhydramine products if they contain active ingredients like acetaminophen. If your dog has glaucoma, high blood pressure, heart condition or urinary obstruction, mention it to your vet.

Weight* (in pounds) Dose (in mg) Frequency (in a day)
5 - 10 10 Twice
10 - 15 15 2 - 3
15 - 35 25 2 - 3
35 - 50 30 - 40 2 - 3
50 - 80 50 - 60 2 - 3
over 80 80 - 90 Thrice

*Weight refers to your dog's weight.
Cetirizine
It is available in 5 mg and 10 mg tablets. it is generally given for eosinophilic inflammation, one of the primary cell types associated with allergies.

Weight (in pounds) Dose (in mg) Frequency (in a day)
less than 15 5 Once
15 - 35 10 Once
over 40 10 Twice
Chlorpheniramine
It is available in 2 mg, 4 mg and 8 mg tablets. It is also available in the liquid form. If your dog has glaucoma, high blood pressure, heart condition or urinary obstruction, mention it to your vet.

Weight (in pounds) Dose (in mg) Frequency (times in a day)
5 - 10 1 - 2 2 - 3
10 - 20 2 - 4 2 - 3
20 - 40 2 - 8 2 - 3
40 - 60 8 - 16 2 - 3
over 60 16 - 24 2 - 3
Prescription Drugs
Clemastine
It is available in 1.34 mg and 2.68 mg tablets. If your dog has heart condition, urinary obstruction or prostatic hypertrophy, mention it to your vet.

Weight (in pounds) Dose (in mg) Frequency (in a day)
5 - 15 0.33 Twice
15 - 25 0.67 Twice
25 - 40 1.34 Twice
50 - 70 1.50 - 2.50 Twice
over 70 2.70 Twice
Hydroxyzine
It is available in 10 mg, 25 mg and 50 mg tablets. It is one of the most effective antihistamines for dogs.

Weight (in pounds) Dose (in mg) Frequency (times in a day)
5 - 10 10 2 - 3
10 - 15 10 - 20 2 - 3
15 - 30 25 2 - 3
30 - 50 50 Twice
50 - 70 50 - 100 2 - 3
over 70 100 - 150 2 - 3
Side Effects
The drugs mentioned above, may have certain side effects on your canine companion, that can include:
  • sedation
  • lethargy
  • diarrhea
  • nausea
  • seizures
  • dry mouth
  • tremors
  • hyperexcitability
  • vomiting
Dogs with liver problems should be given antihistamines very carefully, as these are metabolized by the liver, and thus, they can cause problems internally. These antihistamines for dogs should be given in combination with a proper diet with less fatty acids. Before administering any drugs, it is recommended that you get your dog examined by a vet. It is advisable to follow the dosage and diet instructions given by the vet, to ensure speedy recovery of your beloved pet.
Disclaimer: This article is for informative purposes only, and should not be used as a replacement for expert medical advice.
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