Your dog isn't a stray — they've been vaccinated, and they live a comfortable life with you as their pet parent. But then, one day, you glance over and notice drool and foam coming out of your dog's normally dry mouth. So, why is your dog foaming at the mouth? Read on to learn what may be causing the foam and when you should reach out to your veterinarian.

Benign Causes

If you're tempted to get on the phone with your vet and ask about the foam, you aren't alone. First, what is foam of the mouth, and is it different than drooling? Foaming is the result of panting and drooling at the same time, causing it to be bubbly and form that foamy substance.

Unexpected foaming can be frightening, but it's important to remember that not all excess drooling and foaming is a cause for alarm. In puppies, for example, teething can often lead to drooling. If your dog is less than a year old, keep this in mind if you notice the drooling is gradual. You will likely also see an increase in chewing behavior associated with teething if it indeed is the culprit.

Some medications may also cause dogs to foam at the mouth if they don't like the taste. This is more often observed among cats, but a number of dogs will do this as well, whether they're taking a less than delicious antibiotic or a monthly heartworm preventative.

Causes that Warrant a Visit to the Vet

If you notice your pup is suddenly producing shoestrings upon shoestrings of drool, this is a clinical sign called ptyalism, or hypersalivation. There are many causes of ptyalism in dogs, ranging in seriousness, including the following:

Rabies

One cause of a dog foaming at the mouth is rabies, what often comes to most people's minds. Rabies is a fatal disease in dogs, and a serious risk to human health as well. For this reason, you should never attempt an oral exam if a dog is foaming at the mouth.

Toxins

Another serious cause of sudden foaming at the mouth is the ingestion of some sort of toxin, something that usually carries a better prognosis than rabies. Whether it's because your pup consumed some form of medication meant for humans, a chemical such as lawn pest control or a no-fly food, intense salivation can appear seemingly out of the blue. If there is any chance your dog may have ingested something out of the ordinary, make sure to head to your nearest vet as soon as possible.

Physical Objects

Physical objects in the mouth can also stimulate increased salivation. The culprit can range from anything such as a broken stick lodged in the pup's oral cavity to a painful tooth. Painful teeth are not often visible, thus requiring a veterinary exam and dental x-rays. Bad breath and heavy tartar buildup is often associated with painful teeth, though not always. An oral tumor might also be causing the salivation. Oral melanomas are the most common malignant oral tumor in dogs, while the gums and inside of the mouth are the most common sites for canine melanomas. They may appear as swellings along the gums and may cause facial swelling. They may be black or red and may appear infected or bloody. Bad breath can also be associated with melanomas.