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Ptyalism in Dogs

Ptyalism is a condition characterized by the excessive flow of saliva, also referred to as hypersalivation. Pseudoptyalism (i.e., false ptyalism), on the other hand, is the release of excess saliva that has accumulated in the oral cavity. Saliva is constantly produced and secreted into the oral cavity from the salivary glands. Production of saliva increases because of excitation of the salivary nuclei in the brain stem. The stimuli that lead to this are taste and touch sensations involving the mouth and tongue. Higher centers in the central nervous system can also excite or inhibit the salivary nuclei. Lesions involving either the central nervous system or the oral cavity can cause excessive salivation as well. Diseases that affect the pharynx, esophagus, and stomach can also stimulate excessive production of saliva. Conversely, normal saliva production may appear excessive in animals with an anatomic abnormality that allows saliva to dribble out of the mouth, or are affected with a condition that affects swallowing. Ingestion of a toxin, a caustic agent, or a foreign body can also lead to ptyalism.

Young dogs are more likely to have a form of ptyalism caused by a congenital problem such as a portosystemic shunt. Under normal conditions, the portal vein enters the liver and allows toxic components of the blood to be detoxified by the liver. When a shunt is present, the portal vein is inappropriately connected to another vein, which causes blood to bypass the liver. Yorkshire terriers, Maltese, Australian cattle dogs, miniature schnauzers, and Irish wolfhound breeds have a relatively higher incidence of congenital portosystemic shunts. Enlargement of the esophagus is hereditary in wirehaired fox terriers and miniature schnauzers, and familial predispositions have been reported in the German shepherd, Newfoundland, great Dane, Irish setter, Chinese shar-pei, greyhound, and retriever breeds. Congenital hiatal hernia has been recognized in the Chinese shar-pei. Giant breeds, such as the St. Bernard and the mastiff, are known for excessive drooling.

Symptoms and Types

• Loss of appetite - seen most often in dogs with oral lesions, gastrointestinal disease, and systemic disease
• Eating behavior changes - dogs with oral disease or cranial nerve dysfunction may refuse to eat hard food, not chew on the affected side (patients with unilateral lesions), hold the head in an unusual position while eating, or drop food
• Other behavioral changes - irritability, aggressiveness, and reclusiveness are common, especially in dogs with a painful condition
• Difficulty swallowing
• Regurgitation - in dogs with esophageal disease
• Vomiting - secondary to gastrointestinal or systemic disease
• Pawing at the face or muzzle - dogs with oral discomfort or pain
• Neurologic signs - dogs that have been exposed to causative drugs or toxins, and those with hepatic encephalopathy following consumption of a meal high in protein

Causes

• Conformational disorder of the lips - particularly in giant-breed dogs

• Oral and Pharyngeal Diseases
  • Presence of a foreign body (e.g., linear foreign body, such as a sewing needle).
  • Tumor
  • Abscess
  • Gingivitis or stomatitis: inflammation of the lining of the mouth, secondary to periodontal disease
  • Viral upper respiratory infection
  • Immune-mediated disease
  • Kidney disease
  • Ingestion of a caustic agent, or poisonous plants
  • Effects of radiation therapy to the oral cavity
  • Burns (e.g., from biting on an electrical cord)
  • Neurologic or functional disorder of the pharynx

• Salivary Gland Diseases
  • Foreign body
  • Tumor
  • Sialoadenitis: inflammation of the salivary glands
  • Hyperplasia: over proliferation of cells
  • Infarction: area of necrotic tissue caused by loss of adequate blood supply
  • Sialocele: salivary-retention cyst
  • Esophageal or Gastrointestinal Disorders
  • Esophageal foreign body
  • Esophageal tumor
  • Esophagitis: inflammation of the esophagus secondary to ingestion of a caustic agent or poisonous plant
  • Gastroesophageal reflux
  • Hiatal hernia: stomach bulging up into the chest
  • Megaesophagus: enlarged esophagus
  • Gastric distension: bloating of the stomach
  • Gastric ulcer

• Metabolic Disorders
  • Hepatoencephalopathy - caused by a congenital or acquired portosystemic shunt, where the liver is not able to remove harmful substances from the blood, and the toxins are diverted to the brain
  • Hyperthermia: high fever
  • Uremia: kidney failure

• Neurologic Disorders
  • Rabies
  • Pseudorabies
  • Botulism
  • Tetanus
  • Dysautonomia: disease of the nervous system
  • Disorders that cause dysphagia, or difficulty swallowing
  • Disorders that cause facial nerve palsy or a dropped jaw
  • Disorders that cause seizures
  • Nausea associated with vestibular disease

• Drugs and Toxins
  • Caustic/corrosive toxins (e.g., household cleaning products and some common house plants).
  • Substances with a disagreeable taste
  • Substances that induce hypersalivation.
  • Animal venom (e.g., black widow spiders, Gila monsters, and North American scorpions)
  • Toad and newt secretions
  • Plant consumption may cause increased salivation (e.g., poinsettia, Dieffenbachia)

Diagnosis

There are many different causes for excessive salivation. You will need to give a thorough history of your dog's health, including vaccination status, current medications, possible toxin exposure, a background history of symptoms, and any other possible incidents that might have precipitated this condition. Your doctor will need to distinguish between hypersalivation associated with a condition that is causing difficulty swallowing, from hypersalivation associated with nausea. Depression, lip smacking, and retching are some of the signs your veterinarian will look for. Your doctor will also want to give your dog a complete physical examination, with special attention paid to the oral cavity and neck, along with a neurologic examination. Diagnostic tools may include x-ray and ultrasound imaging to determine whether there is a problem in the structure of the liver, or in any other internal organs. If an immune-related disorder is suspected, your veterinarian may also want to conduct a biopsy of tissue and cells.