Antihistamines for Dogs: Understanding Their Uses and Benefits

When our furry friends suffer from allergies, it can be distressing for both them and their owners. Constant itching, sneezing, and discomfort can lead to a decreased quality of life for dogs. Fortunately, antihistamines can provide relief for our four-legged companions, just as they do for humans. In this article, we'll explore the world of antihistamines for dogs, including their uses, benefits, and important considerations.

What Are Dog Allergies?

Allergies in dogs can manifest in various ways, with the most common being:

• Skin Allergies: These often lead to itching, redness, and skin inflammation. Common triggers include pollen, dust mites, fleas, and certain foods.

• Respiratory Allergies: Dogs can develop respiratory allergies, similar to human hay fever. This can result in sneezing, coughing, and nasal discharge.

• Food Allergies: Certain ingredients in dog food can trigger allergic reactions, leading to digestive problems and skin issues.

• Contact Allergies: Dogs can also be sensitive to substances they come into contact with, such as certain cleaning products or plants.

Related: Dog Skin Allergies

What Do Antihistamines Do for Dogs?

Antihistamines are a class of medications commonly used to alleviate allergy symptoms in dogs. They work by blocking histamine receptors in the body. Histamine is a chemical released by the immune system in response to allergens, and it's responsible for typical allergy symptoms like itching, sneezing, and watery eyes.

In dogs, antihistamines can help reduce the following allergy-related issues:

• Itching and Scratching: One of the most noticeable signs of allergies in dogs is excessive itching. Antihistamines can help relieve this discomfort, making your pet more comfortable.

• Sneezing and Runny Nose: Dogs with respiratory allergies can benefit from antihistamines that alleviate symptoms like sneezing and a runny nose.

• Swelling and Redness: Antihistamines can reduce the inflammation and redness associated with skin allergies.

• Mild Allergic Reactions: In some cases, antihistamines can help manage mild allergic reactions, although severe reactions may require more intensive treatment.

Are Antihistamines a Good Allergy Medication for Dogs?

Yes, they can be. Antihistamines seem to have the best effect when used for an acute allergy flare-up or when started at the beginning of the allergy season. Starting antihistamines when symptoms have been present for many weeks may not be beneficial for the dog.

Types of Antihistamines for Dogs

Several antihistamines are considered safe for dogs, but it's crucial to consult with your veterinarian before giving any medication to your pet. Some commonly used antihistamines for dogs include:

• Diphenhydramine (Benadryl)

• Cetirizine (Zyrtec)

• Fexofenadine (Allegra)

• Loratadine (Claritin)

• Chlorpheniramine

What to Consider Before Giving Antihistamines to Your Dog?

Dosage

The dosage of antihistamines for dogs varies based on their size, weight, and specific needs. Never guess the dosage; always follow your vet's recommendations.

Side Effects

While antihistamines are generally safe, they can have side effects in some dogs, including drowsiness or gastrointestinal upset. Monitor your pet closely after administering the medication.

Other Medications

Inform your veterinarian about any other medications your dog is taking, as antihistamines can interact with certain drugs.

Allergen Avoidance

Whenever possible, try to identify and eliminate the source of your dog's allergies. This might involve changing their diet, using hypoallergenic products, or avoiding specific environmental triggers.

What is the Dosage of Antihistamines for Dogs?

Diphenhydramine (Benadryl): This is one of the more commonly used antihistamines for dogs. The typical recommended dosage is 1 mg per pound (2 mg per kilogram) of body weight, given every 8 to 12 hours. So, for example, if your dog weighs 20 pounds, you would give them 20 mg of diphenhydramine.

Cetirizine (Zyrtec): The recommended dosage for cetirizine is usually around 0.5 mg to 1 mg per pound (1 to 2 mg per kilogram) of body weight, given once daily. However, it's crucial to consult your vet for the appropriate dose for your dog.

Loratadine (Claritin): Loratadine is another antihistamine that can be used for dogs. The typical dosage is 0.1 mg per pound (0.2 mg per kilogram) of body weight, given once daily.

Chlorpheniramine: Dogs under 20 kilograms, 4 milligrams, three times per day. Dogs over 20 kilograms, 8 milligrams, three times per day. 0.25 to 0.5 milligrams per kilogram of body weight, three times per day.

It's crucial to consult your veterinarian before giving any medication to your dog, including antihistamines. They can provide guidance on the specific antihistamine to use, the correct dosage based on your dog's weight and condition, and any potential side effects or interactions with other medications your dog may be taking.

Antihistamine for Dogs Side Effects

Antihistamines are sometimes used in dogs to treat various conditions, including allergies, itching, and motion sickness. While generally considered safe when used appropriately and under the guidance of a veterinarian, antihistamines can have side effects in dogs. 

• Drowsiness: One of the most common side effects of antihistamines is drowsiness or sedation. Some antihistamines, like diphenhydramine (Benadryl), are known for causing drowsiness in both humans and dogs. This can be especially noticeable when higher doses are administered.

• Dry mouth: Antihistamines can cause a decrease in saliva production, leading to a dry mouth. This can be uncomfortable for dogs and may cause them to drink more water.

• Gastrointestinal upset: Dogs may experience digestive issues such as diarrhea, vomiting, or stomach upset when taking antihistamines. This side effect is less common but can occur.

• Increased heart rate: Some antihistamines, like pseudoephedrine-containing medications, can cause an increase in heart rate. These types of antihistamines are generally not recommended for dogs.

• Hyperactivity or restlessness: In some cases, antihistamines can cause the opposite of drowsiness, leading to hyperactivity, restlessness, or agitation in dogs.

What Medications Should Antihistamines Not Be Taken With?

Antihistamines are generally considered safe for dogs when used as directed by a veterinarian. However, they may interact with other medications your dog is taking. Some potential interactions to be aware of include:

• Central Nervous System Depressants

• Monoamine Oxidase Inhibitors (MAOIs)

• Corticosteroids or immunosuppressants

• Certain Heart Medications

• Medications Metabolized by the Liver

Can Dog Antihistamines Be Used to Prevent Motion Sickness in Dogs?

Yes. Although not as potent as maropitant (Cerenia®), antihistamines such as diphenhydramine (Benadryl®) can still be employed to mitigate motion sickness in dogs. For optimal results, it is advisable to administer Benadryl® on an empty stomach for approximately one hour before embarking on a car journey.

Conclusion

In conclusion, antihistamines can be a valuable tool in managing allergies in dogs. They can provide much-needed relief from itching, sneezing, and other uncomfortable symptoms. However, always consult your veterinarian for proper guidance and dosing instructions to ensure the health and well-being of your beloved canine companion. With the right care and attention, you can help your dog live a happier, allergy-free life.