Pets’ allergies can manifest as chronic skin disease, asthma, nasal inflammation, vomiting, or diarrhea. Each sign is a hypersensitivity reaction type attributable to a different underlying mechanism, but an overactive immune system triggers them all. Reactions that occur within minutes to hours of exposure to an offending substance (i.e., allergen or antigen) are type 1 (i.e., acute) allergic reactions, which range in severity from minor and localized swelling to life-threatening anaphylactic shock. Seeing your pet experience an allergic reaction can be upsetting, but our Island Animal Hospital team is here to guide you. Learn to recognize when your four-legged friend is having an allergic reaction and how you can help them. 

What causes allergic reactions in pets?

Allergic reactions are the result of the immune system recognizing and attacking a foreign substance (i.e., allergen or antigen). After being exposed to an allergen several times, your pet can become sensitized to the substance. Your furry pal’s immune system reacts more aggressively with each encounter, triggering a complex cascade of chemical messengers within their body, causing inflammation and signs associated with an allergic reaction. Insect venom, a certain drug or vaccine, or an inhaled substance is usually the offending allergen. Contrary to popular belief, food is rarely responsible for a pet’s acute hypersensitivity reaction.

Allergic reaction signs in pets

Allergic reactions are extremely common in dogs but rare in cats, although they do occur. Signs range from minor, local swelling to a severe systemic reaction (i.e., anaphylaxis). Most reactions are moderate, causing discomfort and swelling but no life-threatening signs. The most common allergic reaction signs include itchiness, hives, facial swelling, vomiting, and diarrhea. However, be aware that severe anaphylactic reactions often also begin this way, but quickly progress to include difficulty breathing, weakness, and collapse. 

What to do if your pet has an allergic reaction

If you see an insect bite or sting your four-legged friend, you should be on the lookout for a reaction. However, many times the cause of a pet’s allergic reaction is unknown and seems to come out of nowhere. The reaction may begin subtly, with something abnormal happening to your pet’s face, and the swelling worsens a few minutes or hours later. A short-coated dog’s hives may appear all over their body. If your furry pal develops these signs, you should seek same-day veterinary care with our Island Animal Hospital urgent care team. These signs make your four-legged friend uncomfortable, but they aren’t immediately life-threatening.

If your pet develops hives or swelling and vomits, has bloody stools, becomes weak, or has difficulty breathing, seek immediate care at your nearest veterinary emergency facility. Although rare in dogs, anaphylactic shock can be fatal. Anaphylaxis comes on quickly, while less severe reactions tend to develop gradually over a few hours.

Treatments for allergic reactions in pets

The standard treatments for mild to moderate allergic reactions include steroids and antihistamines to reduce inflammation and interrupt the abnormal immune response. Depending on the severity of your pet’s condition, our Island Veterinary Hospital team may administer these medications by injection, and prescribe a short course of these medications for you to administer orally to your furry pal at home. Most pets can go home shortly after their visit and do not require long-term observation in the hospital.

Treatment for anaphylaxis is more complex. This condition causes blood vessels in the liver, intestines, and other major organs to dilate, preventing blood from flowing normally. Epinephrine and intravenous (IV) fluids help restore blood flow, while steroids can treat the underlying reaction. Pets may need to remain in the emergency hospital overnight for continued supportive care until they are stable enough to go home. 

Management and prevention of allergic reactions in pets

A vet in blue scrubs holds a bottle of medicine, offering it to a woman in a pink sweater. They smile at each other in the exam room with a clock on the wall. A brown cat sits on the table beside a purple pet carrier.

Most pets who experience an allergic reaction do not have frequent recurrences. However, depending on the allergy type, some pets are susceptible to repeat episodes. A veterinary dermatologist can pinpoint a pet’s allergens and develop a long-term prevention plan, as well as at-home rescue strategies to help prevent them from needing repeated emergency care visits. Always monitor your furry pal after they receive vaccines or new medications, and immediately inform our team if you believe your pet is having an allergic reaction. 

Seeing your pet experience an allergic reaction can be alarming, but most signs can be easily treated through urgent care services. Call our Island Animal Hospital team if your pet has an allergic reaction during our normal business hours, or visit our emergency referral page for information on urgent and emergency care veterinary facilities open after hours and on weekends.