Excessive salivation is referred to as ptyalism. For some breeds, such as Great Danes, excessive drooling is normal; it is just part of the breed.  For other breeds an excess of saliva can point to a toxicity or illness. Several conditions can cause your dog to have excessive salivation:

Stomatitis is the result of bacterial infection and inflammation of the oral cavity. Stomatitis is also known as periodontal disease. Stomatitis can be antibiotic-resistant, so getting treatment as soon as possible will help stop stomatitis before symptoms cause lasting damage. Your dog may seem depressed, reluctant to eat, experience difficulty eating if attempted, and may have bad breath. Your vet may take x-rays, do lab work including a complete blood count, and even order a biopsy of the affected area. 

While drooling in most dogs is a good thing, helping to keep teeth healthy, excessive drooling is not. It can be a sign of gingivitis and periodontal disease. You will notice the gums becoming inflamed and sore. Without treatment, teeth will become loose and either fall out or fracture. If your dog has chipped a tooth (not related to periodontal disease), you will notice excessive drooling as a sign that something is amiss. Cuts, bruises, or other injuries to the mouth or gums may also result in drooling. 

Curious dogs still sometimes manage to come in contact with toxic chemicals and plants even with the best efforts of their owners. Blood or bone meal, often used in gardening, can poison your dog. Ponds that have algae in them are not a good source of drinking water, but sometimes dogs ingest water without our knowledge. Dogs may also accidentally ingest mushrooms. If you suspect your dog has eaten something poisonous, it is best to visit the vet. Any breed or age of dog is susceptible to ingesting something toxic.

When you see excessive salivation, examine your dog’s mouth. If you find objects such as fish hooks, wooden splinters, fabric, or any other foreign object, then it is possible your dog has ingested something he shouldn’t have. Dogs often get splinters lodged in their throats; these objects require surgical intervention. If you don’t see any foreign objects in your dog’s mouth, look for bleeding gums – this is a sure sign your companion has ingested something he shouldn’t have and a trip to the vet for x-rays is in order.

Often a young dog traveling by car will experience nausea due to motion sickness, and this nausea will bring about excessive salivating. While older dogs are not immune to this type of nausea, older dogs have this advantage – the portion of their ears that deal with balance are fully grown. It is possible that this is the cause of nausea in younger dogs traveling by car.

First, make sure that your dog has not been exposed to rabies (excessive salivating is a symptom of rabies). Once you have established this, you may need to see your vet. He will examine your dog and rule out other physical causes for excessive drooling. Your dog may drool simply because he is anxious about riding in the car, may be suffering from stomatitis, or he may have motion sickness. If this is the case, your vet can prescribe a mild medication for these causes. 

Your vet can also find any foreign bodies in your dog’s throat or stomach, although if the object is not evident an x-ray may be required. If you suspect your dog has ingested something poisonous, get him to the vet immediately. Bring anything that can help your vet identify the poison your dog ingested.

If you suspect your dog is suffering from motion sickness, be sure he is facing forward when riding (there are specialty canine seat belts just for this). Lower your car windows to help equalize pressure inside and outside the car (remember, in younger dogs that haven’t fully developed ear structures that support balance, motion sickness has more to do with age than actual stress from riding). 

Gingivitis and other dental issues can be prevented by brushing your dog’s teeth or by giving him healthy treats that help to clean the teeth. Prevent your pet from chewing on dangerous objects or ingesting poisonous products by keeping hazardous items out of reach and providing dog safe toys to keep him stimulated and occupied.

Treating tooth decay in dogs can be expensive, with costs ranging from $500 to $2000. If your dog requires surgery due to an intestinal obstruction, costs can rise as high as $7000.