Most commonly, sudden facial swelling in dogs occurs as a result of an allergic reaction. Other causes can include infection or abscesses, tumours or dental disease.

Allergies are one of the more common causes of facial swelling. Allergic reactions usually occur suddenly, so if your dog is fine one minute and then puffed up like a cloud the next, it is probable that it is due to an unknown allergy. Some causes of allergies include insect bites or stings, certain food or medications, environmental allergens or after vaccinations. In severe cases, the neck may swell and even affect breathing. Mild reactions tend to improve with little intervention and time, while major reactions are considered an emergency.

Another cause of facial swelling may be due to a problem with the teeth or mouth. Tooth abscesses or other dental infections can go deep beneath the gums and cause a pus-filled pocket. This will usually cause swelling beneath your dog's eye. It is important to regularly inspect your pets' mouth so that you notice any changes as soon as possible.

Trauma or an injury to the face, head or skin can lead to facial swelling. Common injuries like animal bites or other wounds can cause large abscesses. Tumours or abnormal growths can similarly occur on the face and head and are sometimes cancerous, sometimes not.

It is important to carefully consider how your pet is responding to a puffy or swollen face, and if in doubt head to your vet. Suspicions that they are struggling to breathe, have an infection, or they could be going into shock or anaphylaxis requires a vet visit.