Facial swelling, especially of the muzzle/nose and around the eyes can be a sign of an allergic reaction. Other symptoms can include hives, itching, pale gums, weakness and vomiting. These reactions are seen most commonly with insect bites or stings however can also be reactions to vaccines or medications. Venomous snake bites can also cause facial swelling and are suspected if there are puncture wounds, often the swelling develops quickly and may not be symmetric, these dogs are often very painful and may try to rub at the area. Please seek emergency veterinary care if an allergic reaction is suspected especially if there was a possibility of exposure to a snake. Antivenin is available for most snake bites but prompt treatment is very important.