My Dog Just Came Inside and Her Eyelids and Muzzle Are Swollen. What’s Going On?

Swelling of the eyelids and face, hives and facial itching (or pawing at the face) are common signs of an allergic reaction. Essentially, this occurs when the dog’s immune system generates an exaggerated response to a foreign substance. While dogs can have allergic reactions to a multitude of things, including medications, pollen, dust and food, abrupt facial swelling after being outdoors is commonly caused by a bee sting or insect bite.

Dogs can also experience a similar reaction to vaccinations, though this can occur whether they’re outdoors or not. No matter what the cause, an allergic reaction can occur immediately or up to 48 hours later. These reactions can range from mild to severe and life-threatening, so if your dog shows these signs, contact your veterinarian as soon as possible.

A Mild Reaction Can Get Worse

Some allergic reactions are so mild you may barely notice them. For example, after a bee sting or insect bite, your dog may experience localized redness or itching of the skin. And after vaccination, it’s not uncommon for a pet to experience some joint or muscle soreness, lethargy or even a mild fever.

If your dog shows signs of a more advanced reaction, including facial swelling, itchiness, vomiting and/or hives or bumps all over the body, see your veterinarian immediately.

In rare cases, dogs can experience a severe allergic reaction called anaphylaxis. Additional signs of anaphylaxis may include difficulty breathing, weakness and collapsing. This can be a life-threatening emergency and can affect major organ systems, such as the gastrointestinal tract, the circulatory system and the lungs.

Seek Veterinary Treatment

You and your veterinarian may never be able to identify what caused your dog’s allergic reaction. But regardless of the underlying cause, the treatment generally depends on the severity of the reaction.

A very mild allergic reaction can be treated with an oral antihistamine for 48 to 72 hours. Your veterinarian can recommend an antihistamine and a dose that’s right for your pet.

In more advanced cases, your veterinarian may recommend other medications to help reduce swelling, provide cardiovascular support, dilate the lower airways to help your dog breathe better and help stop the body’s reaction to the allergen. Sometimes, hospitalization is recommended so your pet's response to treatment can be monitored.

Anaphylactic shock requires aggressive treatment and your pet may require hospitalization with intravenous fluids and potentially other medications to help her recover. 

If you have any concern about the severity of your pet’s allergic reaction, see your veterinarian as soon as possible. Even if you think your pet is experiencing a very mild reaction, legally, veterinary professionals can’t provide drug dosages and assessments over the phone without evaluating the pet, so call for an appointment immediately or seek emergency care.

Preventing Another Reaction

Insect bites can be difficult to prevent. But if the cause of the reaction is known, it should obviously be avoided.

While vaccinations may still be necessary to protect your pet from dangerous and deadly diseases, if your pet has had a vaccine reaction, there are precautions you can take. Work with your veterinarian to consider which infections your pet is at risk for and develop a plan to minimize the number or frequency of vaccinations. 

Administration of several vaccinations at one time should be avoided. If multiple vaccinations are due, individual vaccines should be administered at least two weeks apart to help minimize the amount of immune system stimulation at one time.

If your pet has previously experienced a vaccine reaction, be sure to inform the veterinarian so that proper premedication can be given. With premedication, many dogs can be vaccinated without a reaction.

For pets with a history of vaccine reactions, it's probably not a good idea to use vaccine clinics, because they may not be prepared to administer pretreatment with anti-inflammatory medications or to observe the pet after vaccination. 

If your dog previously suffered a severe vaccine reaction, talk with your veterinarian to determine the best way to proceed in the future.