Allergic Reactions-When to be concerned

Allergic reactions to food, insect bites, pollen are relatively common in pets. Itching and swelling (ears, skin, feet) are the most common symptoms. Clinical signs can last anywhere from a few hours to the whole season. Certain breeds seem to be more prone to allergic reactions than others. For instance, Chihuahuas, Bulldogs and Boxers commonly present to emergency room soon after being bit by an insect. These guys seem to be ‘frequent flyers’ for these events. Some respond to a few doses of benadryl at home while others require a trip to the veterinarian for steroids. Although pets initially respond to treatment, the allergic component remains in the body for a few days and despite medication the pet may experience return of hives and facial swelling, although less severe, over the following 48-72 hours.

chihuahua allergic reaction

While dogs tend to have hives and facial swelling, cats seem more apt to develop red ulcers, called ‘rodent ulcers’ on the lips, red itchy lesions above the eyes or on the temple region of the head. Food allergies frequently result in intense itching of the head and face.

cat with ulcer

These types of common reactions are irritating, inconvenient but generally not life-threatening. They can be managed with a few medications and in a pinch, a cool ice-pack.


The more serious condition, called anaphylaxis, is a rare event where a pet goes into shock immediately (within minutes) after being bit by an insect or receiving a vaccine. These pets often will collapse and experience vomiting and diarrhea. Breathing may become difficult as well. It is not unusual for a pet owner to not even realize that their pet has been stung by an insect and these guys can stump even experienced veterinarians when they initially present to the emergency room. As they present for shock, however, they are generally treated for shock, and measures to increase blood pressure are taken. This often includes giving a dose of steroids if blood pressure does not respond to common measures taken with shock. If a pet owner has a dog or cat known to have anaphylaxis, an EpiPen or syringe of epinephrine should be kept at home and taken with the pet when away from home. Dogs weighing over 45 lbs can use the standard 0.3 mg epinephrine EpiPen. Dogs weighing between 20-45 lbs can use the EpiPen Jr. For dogs weighing less than 20 lbs and cats, it may be more appropriate to have a syringe at home containing the proper dose as even the EpiPen Jr. may be too much. Your veterinarian can show you how to administer an injection to prepare you for an emergency situation.

IV fluid puppy

If you have given your pet an injection of epinephrine due to a severe allergic event, he or she may look great, but keep in mind the epinephrine is very short acting and you need to take your pet to the emergency room immediately so that longer acting medications and supportive measures can be given.

In Summary signs of anaphylaxis:

*vomiting/diarrhea soon after being stung
*collapse/weakness after being stung
*signs of shock without any known sting is possible (but rare)

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