Large brown dog sitting with owner.

What Causes a Dog to Foam at the Mouth

Have you ever wondered why your lovely family dog sometimes foams at the mouth? We usually associate foaming at the mouth with the deranged condition of rabies, so seeing your dog displaying the same characteristic can be worrying. But, fortunately, there are other reasons for this behavior - that aren’t so ominous. 

Related: Why Does My Puppy Breathe So Fast When Sleeping?

7 Reasons Your Dog is Foaming at the Mouth

Here are seven possible reasons for your dog’s foaming at the mouth:


Dogs are highly sensitive to their environments and to you, their dog parent. They pick up on your stresses, as well as the many things that can negatively affect them. Their physical response isn’t much different than ours in certain circumstances. Our canine friends produce an excess of saliva, causing them to drool. Drooling is their body’s automatic response to stress and anxiety. You may notice this kind of reaction if you move house and your dog is stressed because of the new surroundings. Feeling uncertain and possibly, unsafe, they begin to drool and hyperventilate. Those two actions paired together cause foaming at the mouth.     

Stress may even make your dog hold its body in odd positions or seem almost paralyzed. This could become a habitual response to stressful situations. 


Dogs love to exert themselves. They enjoy running and playing, but even they can do too much. When they’re overexerted, they pant excessively - inhaling more quickly than exhaling. You already know that when your dog is very active, they drool quite a lot. The saliva turns to foam with the rapid inhaling

The foaming will decrease when they rest and aren’t using so much energy. But if they start to drink water in their excited state, they’ll produce more foam. 

Digestive Issues

Foaming at the mouth can also happen if your dog ingests something that doesn’t agree with them. Extra salivation is made to rid their mouth of the taste, and it begins to create foam. This won’t usually last very long. Once they have the terrible taste out of their mouth, they will stop the excess salivation, and the foam will disappear. 

However, the foaming could actually increase if your dog is nauseous enough to vomit. Have you ever noticed that just before you vomit, your mouth creates more saliva? Well, this is what happens to your dog. The increase of saliva, in turn, increases the foam for a while. If they do vomit, they will experience relief from the nausea. Depending on what they have ingested, this relief may or may not be permanent. If they can’t seem to stop vomiting, the issue may be more severe, and they may need to see the vet.

Related: Why Do Dogs Like to Be Pet?

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If your dog is in stressful circumstances, it may become anxious. As stated earlier, the stress will cause them to drool disproportionately. Here are some reasons your dog may experience anxiety.

  • Past Trauma. Not every pet parent is a good one. Some dogs have experienced abuse or neglect that has left them traumatized. Even after things are better, finding themselves in triggering situations can bring back the same anxiety and physical responses. 
  • Separation Anxiety. Your dog is fearful that you will abandon them. This is why they are so sad when you leave them to go to work or vacation. 
  • Socialization. Like us, dogs have different personalities. Socialization may be more challenging for some than for others. If dogs are socialized with others when they’re still puppies, it can become a stressful situation for them later.
  • Illness. Dogs with conditions that affect their nervous systems, like hyperthyroidism, diabetes, or encephalitis, are likely to suffer from anxiety. 
  • Genetic. Some dogs are more disposed to anxiety than others. For instance, German Shepherds, Poodles, Siberian Huskies, and Terriers are among breeds that tend to be anxious. Additionally, any dog that is especially intelligent and can more easily notice changes to its environment, can also become anxious. 

A part of being a good pet parent means knowing what causes your dog anxiety and minimizing it as best you can. 

Happy long-eared dog with mouth opened.


Foaming will be the immediate result if your dog ingests poison. Your dog’s body will try to get rid of the poison by creating more saliva to coat the mouth and throat and to speed the process of digestion. The saliva turns to foam. The foaming won’t go away until they get medical treatment or, in the absence of treatment, death. So, if you see your dog foaming at the mouth and trying to vomit, consider taking them to the vet immediately. 

Dental Problems

If your dog is suffering from cavities or other periodontal issues, like gingivitis, they may hang their mouths open to deal with the pain and discomfort. Holding the mouth open will naturally cause the production of more saliva. Your dog may direct his tongue and breathe away from sore areas, and when you add to that the excess saliva, you have foam.  

Difficulty Swallowing

If your dog swallows something that gets lodged in its throat, you may notice desperate behavior. The obstruction may not block their breathing but can stop them from swallowing effectively. Your dog may hyperventilate and drool, the magic combination that creates foaming mouths. 

If you can, open their mouth and look for the obstruction. If you’re able, reach in and pull the object out. Do this carefully and gently to avoid inflicting any more pain or damage. If the task is beyond you, spare no time getting your dog to the vet, where they have the tools and expertise to help your dog. 

If the obstruction is not a foreign body but some kind of growth in your dog’s throat, get them to the vet immediately. It may not be anything to worry about, but you need to have a vet look at it. 

Related: Why Does My Dog Lay On Me?

Final Thoughts on Foaming at the Mouth

There are several reasons for your dog to foam at the mouth. It is a response to anxiety, stress, or overexertion. It could also be the physical reaction to digestive problems, poisoning, dental issues, or an obstruction in the throat. Mostly, this behavior is not problematic, but sometimes it can be an indicator of a much more serious problem. As always, know your dog and the circumstances that affect them. 

Along with your love and attention, how about giving your furry friend a yummy treat! Runball has a line of treats and toys to keep your dog happy!