Diseases That Cause Dogs to Foam at the Mouth

By Lisa McQuerrey

Foaming at the mouth. That's rabies, right? Probably not. Most oral foaming in canines is related to a combination of salivating and panting, or hypersalivation. A dog may foam at the mouth for many other reasons. Dogs who have been vaccinated for rabies are at low risk for the disease. Take all cases of oral foaming seriously, however. Foaming at the mouth can signify a life-threatening emergency, especially if poison or trauma is involved.

Common Causes of Foaming

Your dog may foam at the mouth if he’s anxious, if he eats something he doesn’t like the taste of, if he's motion sick or if he has an upset stomach. He may also drool if he has an injured or diseased tooth or has a hard time swallowing. Excessive salivation and foaming are potential side effects of some types of medication. Heavy panting and drooling can also be early warning signs your dog is getting overheated.

Accidental Poisoning

A dog who ingests poison may foam at the mouth, become disoriented or have convulsions. If you suspect poisoning, get vet attention right away. Store chemical yard fertilizers and pesticides where your dog can’t get them, and keep human medications away from your pup as well.

A dog sprayed in the face by a skunk may have a reaction that includes foaming at the mouth, though the telltale strong odor should alert you to the difference.

Canine Rabies

Foaming at the mouth is a classic indication of rabies -- the foaming results from paralysis of the throat and jaw muscles. Other signs of rabies include aggression, restlessness, change in personality, loss of balance and appetite, fever, and sensitivity to light and sound. Use caution in handling a dog who may have rabies, which is transferable to humans.

Canine Pseudorabies

Pseudorabies, also known as mad itch, is not contagious to humans but can pass from infected swine to dogs. Extreme itching, fever, foaming, excess salivation and neurological problems are characteristic symptoms. Report suspected rabies or pseudorabies cases to your vet immediately.

Canine Distemper

Distemper is a virus that affects a dog’s central nervous system, causing breathing problems and gastrointestinal upset. While your dog may not necessarily foam at the mouth, he may cough and may have thick mucus coming from his mouth and nose. Weakness, fever, sudden diarrhea and vomiting are symptoms of the disease. Immediate vet intervention is necessary, as the infection is fast-moving.

Seizure Disorders

A dog experiencing a seizure may exhibit hypersalivation or foaming at the mouth. Seizures may result from a metabolic disorder like kidney disease, epilepsy, trauma or head injury, or from a stroke, a neurological problem or low blood sugar. A dog experiencing a seizure, with or without foaming at the mouth, requires fast medical care.

Recognizing What Foam Means

Identifying what’s going on with your dog by considering his mouth foam alone can be tricky. The appearance of oral discharge may range from thick spittle to a condition that looks like your dog just brushed his teeth -- a bubbly white substance hanging from his jaws. It’s vital to take the symptoms and behaviors he’s exhibiting with the foaming into consideration as well.