Gut Reaction

Do dogs have allergies?

Like humans, dogs can suffer from allergies. It is one of the most common problems I see as a small-animal veterinarian. Many dogs experience some kind of allergy during their lifetime, whether it is due to environmental factors, food or other irritants.

An allergy occurs when a dog’s immune system overreacts to substances that are usually harmless. These substances, known as allergens, trigger an allergic response when they are inhaled, eaten or come into contact with the dog’s skin. During this reaction, the dog’s body mistakenly identifies these normal environmental substances as threats, leading to a variety of physical symptoms. The severity of the reaction varies greatly and can range from mild discomfort to severe, life-threatening conditions.

The immune reactions involved in allergies are complex. Most reactions involve allergen protein molecules combined with antibodies in the blood that attach to a cell called a mast cell. Mast cells are found in many tissues throughout the body. When an antigen and antibody react with mast cells, the mast cells release potent chemicals, such as histamines, causing local inflammation. Itching, redness and swelling develop. This inflammation results in the various signs associated with an allergic reaction.

Are allergies inherited?

Yes, allergies can be genetic, and certain breeds are more predisposed to developing allergies. While not all allergies are directly inherited, genetic makeup can make a dog more susceptible to developing allergic reactions to environment or diet. In my practice, Pugs and Dachshunds seem to have a higher rate of allergic reactions to vaccines than other breeds.

What are the different types of allergies in dogs?

Dog allergies fall into several categories, each with its own set of triggers and symptoms.

Environmental allergies are triggered by allergens found in a dog’s surroundings. They react to pollen, mold, dust mites, grass, animal dander, and perfumes and deodorants. Dogs with environmental allergies often suffer from seasonal symptoms, but indoor allergens can cause issues all year.

Food allergies in dogs are less common than environmental allergies but can cause severe reactions. Proteins are the usual triggers, including chicken, beef, dairy or wheat. Less common allergens are soy, grain and eggs. Symptoms can range from vomiting and diarrhea to skin problems.

Flea allergy dermatitis occurs when the dog is allergic to flea saliva. Even a single flea bite can trigger an intense allergic reaction, leading to severe itching, inflammation of the skin, and secondary skin infections.

Atopic dermatitis is the term for skin allergies. These are often related to environmental allergens. Dogs will be scratching, licking and biting at their skin. The continuous irritation can lead to hot spots, hair loss and bacterial skin infections.

Contact allergies are less common and occur when a dog’s skin reacts to direct contact with substances like certain plastics, fabrics or cleaning products. Itching and localized skin irritation are signs of a contact allergy.

Other potential allergens include bites from bees and wasps, prescription medications and vaccinations.

What are the symptoms of an allergic reaction?

Allergic reactions in dogs can present in many different ways, ranging from a mild skin irritation to more severe, life-threatening conditions. Recognizing the different types of allergic reactions will help you get the right treatment for your dog.

Itchy, inflamed skin that causes dogs to excessively lick and chew at themselves is a sign of environmental, food, flea-bite allergies or a combination of all three. Sores develop on the skin and become infected.

Dogs with allergies often suffer from recurrent ear infections. Similar to humans, some dogs will have a runny nose and watery eyes, and sneeze frequently. This is a response to inhaled allergens like dust and pollen. It is important to determine the source of the underlying allergy.

Hives, or urticaria, are raised, itchy bumps on the skin. They develop as a reaction to insect stings, certain medications or foods. Hives cause significant discomfort, but they are more alarming in appearance than they are dangerous. However, hives can be a precursor to more severe reactions and should be monitored closely.

Allergic reactions can cause swelling of the face, especially around the eyes and lips. In more severe cases, the throat may be affected. Facial swelling can be distressing for the dog, and if it involves the throat, can make breathing difficult. These cases require immediate veterinary attention.

Anaphylactic shock is the most severe form of allergic reaction. It can occur within minutes of exposure to the allergen and be life threatening. Symptoms include sudden weakness, labored breathing, vomiting, diarrhea and collapse. Anaphylaxis requires emergency veterinary care to stabilize and treat the dog.

How are allergies diagnosed?

Diagnosing allergies requires a comprehensive examination by a veterinarian. The process may include a detailed review of the dog’s medical history, physical examination and specific allergy tests, such as blood tests or skin-prick tests. In some cases, an elimination diet may be recommended to identify food allergies.

For resistant cases, your veterinarian may recommend referral to a board-certified veterinary dermatologist.

What is the treatment for allergies?

Depending on the type and severity of the allergy, treatment can include antihistamines, corticosteroids or other medications to reduce the symptoms. For skin allergies, topical treatments like medicated shampoos or ointments provide relief.

Dietary modifications are necessary when dealing with food allergies. A hypoallergenic food is recommended for eight to 12 weeks. During the feeding trial, dogs should not eat any other foods, including treats, human foods or flavored medications. Hypoallergenic diets either have limited ingredients with an uncommon protein source (rabbit, kangaroo) or are processed in a special way called hydrolyzation. This makes the food less likely to cause allergic reactions.

The results of allergy testing may indicate the need for immunotherapy, or desensitization injections or oral medication, as a way of managing environmental allergies. The goal of immunotherapy is to make the immune system less reactive to the allergy-causing substances. This is the best long-term approach to allergy control, especially in younger dogs that experience symptoms most of the year.

Newer medications such as the daily oral tablet oclacitinib (Apoquel)and the monthly injection monoclonal antibody (Cytopoint) are effective medications prescribed to stop the itching associated with allergic reactions. Unlike corticosteroids, these medications are safe for dogs to take on a regular basis.

Can dogs take human allergy medication?

Yes, in some cases, dogs can be given human allergy medication. However, it is important to consult with your veterinarian before administering any medication to your dog. Your vet can determine the appropriate dosage and monitor your dog for any potential side effects.

Diphenhydramine (Benadryl) is an antihistamine that can help relieve itching, sneezing and runny nose. Cetirizine (Zyrtec) is also an antihistamine that is generally safe for dogs. Loratadine (Claritin) is another antihistamine that can be used to treat allergies in dogs.

The dosage of human allergy medicine for dogs must be adjusted based on their weight. Dogs with underlying health conditions, such as kidney or liver disease, may not be able to take human allergy medicine. Some of these medications may interact with other drugs your dog is taking. The possible side effects include drowsiness, lethargy and gastrointestinal upset.