You can think of all the things that dogs can get into either in the house or outside. My sister’s dog got a hold of a frog the other day, put it in her mouth and then spit out the frog. She made sure the frog was okay, but the dog started foaming at the mouth, salivating and all that. They got really scared and called the emergency clinic. They said, “Oh the toad probably got scared and urinated in the dog’s mouth. That’s what caused the foaming.” I’ve known of snakes that secrete a substance that would make a dog foam in the mouth after they touched them, not poisonous snakes but worms, garter snakes, or grass snakes. When dogs get a hold of them, sometimes they foam.
Certain substances they get a hold of in the environment – dirt, for example – will sometimes cause them to foam. You can also get something that’s kind of like foaming but it’s really just hyper-salivation. Some dogs when they get nervous, they will salivate more than usual. I’ve seen dogs that go into the vet clinic and they’re really kind of nervous and they’ll have strings of saliva. I’ve seen other dogs that think they’re going to get fed with tidbits and so that gets their salivary glands going. They’ll either have strings of saliva or foam or blow bubbles. They’re salivating a little bit extra because they’re waiting on that treat that you’re going to give them.
Puppies are the worst about foaming at the mouth. A lot of times, what gets in their mouth they swallow. Older dogs seem to have a little bit more common sense. Many times, they’ll taste something that’s toxic and they’ll spit it out.
Sometimes foaming at the mouth can really be benign. Most of the time, it’s something that they got in their mouth that irritates their mucus membrane. So if your dog is foaming at the mouth please don’t consider it to be a mad raging psycho dog, it’s simply something that they tried to taste or play with that caused it.