Your pet’s immune system can overreact to many environmental allergens, and signs such as itchy skin, a swollen face, hives, gastrointestinal (GI) issues, and trouble breathing can indicate your pet is having an allergic reaction. Our Family Veterinary Care of Oakdale team knows how upsetting watching your pet have an allergic reaction can be, so we provide information about what causes this condition in pets and how you can help your affected four-legged friend.

Pet allergy basics

Normally, your pet’s immune system, which includes antibodies, white blood cells (WBCs), mast cells, complement proteins, and other factors, defends their body against foreign substances (i.e., antigens). However, in susceptible pets, the immune system can overreact when exposed to certain substances (i.e., allergens) that are typically harmless, causing an allergic reaction. Allergens can cause a reaction when they contact your pet’s skin or eyes or are ingested, inhaled, or injected. Allergies can be triggered in numerous ways, including:

  • Exposure to environmental allergens, such as tree, grass, and weed pollens, that are present during certain seasons
  • Exposure to environmental allergens, such as dust and mold, that are present year-round
  • Taking a medication
  • Eating certain foods
  • Touching certain substances
  • An insect bite or sting

If your pet is susceptible to an allergic reaction, their immune system produces an antibody type, called Immunoglobulin E (IgE), when first exposed to the allergen. IgE binds to basophils, a WBC type, in the bloodstream, and to mast cells in the tissues. The first exposure typically sensitizes your pet to the allergen, but does not cause signs. When your pet next encounters the allergen, the IgE carrying basophils and mast cells produce substances, such as histamine, prostaglandins, and leukotrienes, that cause a mild-to-severe reaction cascade, irritating, inflaming, and harming tissues. These reactions can range from mild to severe.

Common pet allergies

Mild to moderate allergic reactions in pets most commonly result in dermatologic issues, such as itchiness, hair loss, and skin lesions. Secondary skin and ear infections can also occur without appropriate management. The most common pet allergies include:

  • Flea allergy dermatitis (FAD) — Many pets are allergic to a flea’s saliva, and a bite from a single flea can lead to excessive itchiness. Skin lesions and hair loss are most commonly noted on the lower back, inner thighs, and abdomen. In many cases, problematic fleas cannot be found in the pet’s coat because they groom the parasite away, but flea dirt is commonly found in the pet’s coat and their bedding. Treatment involves completely eradicating fleas from your pet and their environment, including other pets they contact. Providing year-round flea prevention also is critical for controlling FAD. 
  • Atopy — Environmental allergies in response to pollen, dust, and mold, are known as atopy in pets. Affected pets have a dysfunctional skin barrier that allows allergens to penetrate and cause inflammation. Most affected pets start exhibiting signs between 1 and 3 years of age. Treatment is typically multi-modal, and involves bathing, anti-inflammatory medications, anti-itch medications, limited exposure when possible, and hyposensitization therapy to desensitize the pet to the causative allergen.
  • Food — Pets can also be allergic to ingredients in their food, most commonly proteins such as chicken, beef, eggs, and dairy. Most affected pets start exhibiting signs when they are younger than 6 months or older than 5 years. A food elimination trial is necessary to determine the causative ingredient that, when determined, should be forever eliminated from your pet’s diet.

Some pets are affected by multiple allergy types, and diagnosis and management can be challenging. Ongoing veterinary intervention is critical to ensure allergic pets are managed as well as possible.

Concerning allergic signs in pets

Some pets have severe allergic reactions, most commonly to insect stings, medications, and certain foods. Signs may include hives, facial or limb swelling, vomiting, and diarrhea, and may escalate to anaphylaxis, a condition that affects your pet’s respiratory and circulatory systems and results in difficulty breathing, wheezing, collapse, and seizures. 

How to respond to your pet’s allergic reaction

If your pet has itchy skin or mild GI signs, schedule an appointment with our Family Veterinary Care of Oakdale team, so we can diagnose the underlying problem and devise an effective management plan. But, if your pet exhibits hives, facial or limb swelling, excessive vomiting or diarrhea, difficulty breathing, seizures, or collapse, they need emergency veterinary care.

Treatment for your pet’s allergic reaction

Allergic reactions that don’t progress to anaphylaxis are typically treated with antihistamines and corticosteroids, and your pet may need to be kept for a short observation period or, depending on their condition, they may be sent home on a course of antihistamines and/or steroids.

If your pet experiences anaphylaxis, we intravenously inject epinephrine and keep them for ongoing treatment and monitoring.

Pets who have an allergic reaction need appropriate veterinary care. If your pet has an allergic reaction, contact our Family Veterinary Care of Oakdale team, so we can provide the care they need.