Multiple causes result in excessive drooling in dogs. WebMD reports that anxiety, anticipation of food, dental problems, heat stroke, distemper, rabies, tumors and motion sickness are all potential causes of hypersalivation. Cysts, tumors or physical injuries are also potential sources.
PetMD recommends getting a dog checked by a vet immediately if it starts drooling excessively for more than a few minutes or the drooling reoccurs regularly. This is especially true if it is accompanied with changes in behavior, such as loss of appetite, irritability, aggressiveness, vomiting or excessive pawing of the snout. If the dog recently ingested a foreign substance like a toxin or something it cannot digest properly, immediate vet intervention is needed to prevent serious injury, poisoning or death. Examples of substances that cause excessive drooling are cleaning products, animal venom and various types of plants.
Treatment depends on the underlying cause of the drooling. WebMD recommends the professional draining of any cysts found in the mouth if possible, but surgery is more common and effective. In extreme cases, a salivary gland may be removed. Tumors of the salivary gland are very rare but are most frequently malignant. Frequent checkups are likely needed after the cause of the drooling is initially treated to ensure the dog is healthy, properly nourished and comfortable.