21 Jun Excessive drooling in Dogs
To comprehend the meaning behind excessive drooling in dogs, it’s crucial to understand the normal anatomy and physiology of saliva production.
Dogs constantly produce and secrete saliva into their oral cavity from salivary glands. There are four pairs of major salivary glands in dogs: the parotid, mandibular, sublingual, and zygomatic glands, along with several minor ones that drain within the oral cavity.
Saliva serves multiple functions, such as lubricating food, aiding in the transportation of food bolus through the esophagus, keeping the mouth moist, regulating temperature through evaporative cooling, cleansing the oral cavity, reducing oral bacterial growth, and protecting oral tissues.
While saliva is primarily composed of water, it also contains enzymes for carbohydrate digestion, mucus, and salts. Saliva production is regulated by the body’s autonomic nervous system.
Certain dogs naturally produce more saliva than others. Breeds like Saint Bernards, Mastiffs, and Newfoundlands, known for drooling, don’t necessarily have excessive saliva production. Their loose lip folds fail to confine saliva within the oral cavity. Brachycephalic breeds, such as Bulldogs, tend to drool more due to skin flaps on their faces that trap saliva.
Excessive drooling in dogs can be categorized into two types:
- Excessive saliva production (ptyalism)
- The inability to swallow normal saliva production (pseudoptyalism).
Chronic ptyalism is often caused by reluctance or inability to swallow rather than increased salivary flow or production.
Physiological causes of increased saliva production in dogs include hyperthermia (overheating), excitement, and feeding. Heat and excitement trigger acute onset of excessive drooling without other noticeable signs of illness.
Pathological reasons for excessive drooling in dogs may stem from various underlying medical conditions.
To differentiate between potential causes of drooling, a comprehensive medical history and physical examination are necessary, performed by a licensed veterinarian.
An important aspect of the examination is a thorough oral examination by a veterinarian, checking for signs of oral pathology like periodontal disease, stomatitis, immune-mediated disease, tongue lesions, or lip fold abnormalities. Acute exposure of internal tooth contents, ulceration in the oral cavity, and foreign bodies are common oral causes.
Dogs have a tendency to put foreign objects in their mouths, which can result in small or even large objects becoming trapped between the teeth or in the throat. Hazards include wood chips, plastic pieces, bone fragments from chewing on bones, and strings.
Signs of orofacial discomfort in pets may include pawing at the face/mouth and changes in eating behavior. Any changes in saliva color, such as blood-tinged or yellow (purulent), could indicate a primary oral problem.
If no oral cause is found for excessive drooling, other body systems like the neurological system, gastrointestinal system, and salivary glands should be considered.
If the excessive drooling is suspected to be secondary to organ system pathology, blood work and advanced imaging may be recommended.
The incidence of salivary gland disease in dogs is generally low, with tumors of the salivary gland tissue accounting for approximately 30% of cases.
Sialadenitis, inflammation of one or more salivary glands, represents a significant portion of salivary disease, both as a primary and secondary condition. Sialadenitis often manifests as obvious enlargement of the salivary glands, potentially leading to the formation of salivary mucoceles (sialoceles). Salivary mucoceles involve the accumulation of saliva in soft tissue surrounding the glands and account for up to 9% of all salivary gland diseases. Causes can include injury, infection, or immune-mediated disease.
Sialadenosis is a non-inflammatory enlargement of the salivary glands, commonly affecting the mandibular salivary glands. The cause of this condition is unknown, and the affected glands are typically painless but enlarged.
Ptyalism can occur in cases where there are congenital (present at birth) enlarged salivary ducts, although these primary salivary gland abnormalities are rare. They can be effectively managed through surgery performed by a board-certified veterinary dentist or surgeon.
Gastrointestinal disorders can often cause nausea, leading to ptyalism in both dogs and humans. Esophageal and gastric issues can also result in excessive drooling. Dogs with severe renal or liver dysfunction may exhibit ptyalism, usually accompanied by other systemic signs of illness. Halitosis (bad breath) may indicate oral, esophageal, or gastric diseases.
Abnormalities of the nervous system, such as seizures, infectious diseases (like Rabies virus), and dysfunction of cranial nerves directly connected to the brain, can cause excessive drooling.
When evaluating patients with ptyalism or pseudoptyalism, it is important to consider recent exposure to toxins, medications, and topical products for humans and animals. These substances can have a bitter taste or be harmful to oral tissues.
- Examples of toxic substances include household cleaners, certain plants/trees (like the Kentucky coffee tree and poinsettia), insecticides/pesticides (such as boric acid and aldicarb), rodenticides (like zinc phosphide), human sleep aids (such as zolpidem), mushrooms (like Amanita muscaria), Metaldehyde, human tricyclic antidepressants (like clozapine), and 5-hydroxytryptophan (found in Griffonia seed extract).
- Envenomization from spiders, scorpions, toads, or coral snakes can also result in excessive drooling.
- Trauma to the oral cavity, including electrical cord injuries, should also be considered.
Vaccination history is also crucial, particularly regarding the Rabies virus, as it poses a significant risk to both veterinary and human health. This life-threatening disease requires immediate notification of the proper health authorities if any animal or human is suspected of having Rabies. Other infectious causes may include systemic bacterial infections like leptospirosis.
While young dogs are more prone to ingesting toxins or foreign objects, adult dogs can be affected as well. The duration of ptyalism is important, as it can help differentiate between oral trauma and cancer in some patients.
Treatment for excessive drooling depends on the underlying cause. In cases of toxin exposure, decontamination (often involving activated charcoal), supportive care (including hospitalization and fluid therapy), or specific antidotes (if available) may be recommended.
If an oral cause is identified, a a full mouth assessment under anesthesia may be necessary, followed by imaging of the oral tissues. Surgical intervention is typically warranted for primary salivary gland diseases and dental issues associated with excessive drooling.
If you suspect your dog has ptyalism or pseudoptyalism, it is important to seek early diagnosis and treatment. Schedule an appointment with your primary care veterinarian or consider visiting Apex Veterinary Specialists in Englewood, CO, for specialized care from a veterinary dentist.