Allergies are the overactive reaction of the immune system to a protein that the body sees as an intruder. The specialized cells that the body uses to fight these invaders are called mast cells, and when they are activated, they release histamine, which has an inflammatory effect on the tissues it comes into contact with. This can result in the itchy and inflamed skin conditions characteristic of an allergic reaction in canines. Allergic reactions in canines are most apparent on their skin, and there are several medications, both in nature and man-made, that can help relieve the itchiness that allergies produce.

Histamine released onto the skin by the immune system during an allergic reaction can cause painful swelling and itching. There are several options for easing the discomfort from allergies.

Skin reactions that are not located at the contact location are often concentrated around the face and groin, under the front legs, or between the toes.

Antihistamine - These medications are designed to block the t cell from releasing histamine into the bloodstream, stopping the reaction before it starts. Antihistamines are not as effective for dogs as for humans, and tend to lose efficiency over time. Benadryl and Hydroxyzine would be examples of antihistamines.

Antipruritic - These medications are designed specifically to target the symptom of itching. Oclacitinib is an example of an antipruritic for canines.

Anti-inflammatory - These medications work by reducing the swelling that may be contributing to the itchiness and the discomfort. It is important to use an anti-inflammatory that is formulated specifically for dogs, or that you get approval from a veterinary professional. Some human anti-inflammatory medications, such as acetaminophen and ibuprofen, can be deadly to canines.

Allergies in canines are a result of an inappropriately aggressive response of specialized immune cells known as mast cells to a protein that is introduced to your pet in one way or another. The dermal symptoms of allergy are the same whether it is a contact allergy, an environmental allergy, or even a food allergy. Either synthetic or naturally occurring proteins may stimulate the mast cells into releasing histamine. Histamine’s inflammatory effect is what causes the majority of the itching and swelling characteristic of an allergic response.

It is important to be sure that the condition that you are treating is, in fact, an allergy. The symptoms that your dog will be showing should prompt your veterinarian to collect skin sample during the general physical. This is so that a microscopic evaluation of the skin cells, called cutaneous cytology, can be completed in order to search rule out alternatives like flea infestations or yeast infections. The veterinarian may also request routine tests such as a complete blood count and a biochemistry profile. These tests may expose eosinophils, a specialized type of white blood cell that is indicative of an allergic reaction. A small amount of the suspected allergen or allergens may be injected into the skin to confirm that suspicion. In the event that the allergy is a food related allergy, dietary trials are often the best method to uncover which food the patient is reacting to.

There are many natural remedies to itching skin. Colloidal oatmeal (oatmeal ground into flour) is an inexpensive and safe treatment that can be found in many pantries, and essential oils such as rosemary, peppermint, and lavender can help relieve the swelling and itching associated with allergies. Even with natural remedies, your veterinarian should be consulted before starting treatment. Certain oils that are remedies for humans, such as tea tree oil, are poisonous for dogs. There are several ointments, shampoos, and sprays that are available on the shelves of your local pet store that incorporate medications like topical antihistamines and anti-inflammatory preparations, to help ease the itching caused by allergies. Oral antihistamines for dogs are prescription based, but there are a few over-the-counter medications that can be used effectively for canines as well as humans. Medications like Benadryl (diphenhydramine), Chlor Trimeton (chlorpheniramine), and Zyrtec (cetirizine) can be effective in treating allergic reactions, and is often recommended off label. A veterinary professional should be consulted before using these medications, as the dosing for dogs is quite a bit different than dosing for people and it can vary based not only on weight but also based on the dog's condition and other medications he may be taking.

Although glucocorticoids have been successfully prescribed to ease allergy symptoms for decades, long term use can induce new disorders such as delayed wound healing and diabetes. Recent advancements have been made in the area of antipruritic medications for animals and there are now effective medications with fewer long term side effects such as cyclosporine (Atopica) and oclacitinib (Apoquel).

Allergen-specific immunotherapy may be another option for animals that are bothered by unavoidable or severe allergic reactions, especially in canines with  indicators that are present for at least four to six months of the year and that are resistant to antihistamines. This treatment works by determining which allergens are causing the reactions with a patch test, and then creating a personalized injection with those allergens in order to desensitize the immune system to the substances that are causing the reaction. Although immunotherapy injections have returned mixed results overall, they seem to be somewhat more effective with environmental allergies. Recent advancements have been made in sublingual versions of this allergen-specific immunotherapy and trials appear promising.