SYMPTOM
Drooling
Excessive saliva production or visible drool that is new, increased, or occurs outside of mealtime contexts.
Oral and dental disease
Conditions affecting the teeth, gums, tongue, or oral mucosa are among the most common causes of increased drooling. Advanced periodontal disease, tooth root abscesses, fractured teeth with exposed pulp, stomatitis (inflammation of the oral mucosa), and oral ulceration can all stimulate excessive saliva production as a protective response. The drooling may be accompanied by halitosis, reluctance to eat hard food, or visible changes in the gums or oral tissues.
Oral foreign bodies or masses
Objects lodged between the teeth, embedded in the gums, or stuck in the throat can produce sudden-onset drooling as the animal attempts to dislodge or cope with the foreign material. Similarly, growths within the oral cavity, including benign and malignant tumours, can stimulate saliva production, particularly if they become ulcerated or interfere with normal swallowing. Foreign body-related drooling typically has an acute onset, while mass-related drooling tends to develop more gradually.
Nausea
Nausea from any cause produces increased saliva production as a protective mechanism. Motion sickness, gastrointestinal upset, vestibular disease, medication effects, and systemic illness can all trigger nausea-related drooling. This type of drooling is often accompanied by other signs of nausea such as lip-licking, frequent swallowing, restlessness, or reduced appetite. The drooling typically correlates temporally with the nauseating stimulus and may resolve when the nausea subsides.
Neurological
Conditions affecting the nerves that control swallowing, facial muscle function, or salivary gland regulation can produce drooling through impaired clearance of normally produced saliva rather than overproduction. Facial nerve paralysis, trigeminal nerve dysfunction, or conditions affecting the swallowing reflex can all cause saliva to accumulate and overflow from the mouth. Neurological causes of drooling may be accompanied by other signs such as a dropped jaw, inability to close the mouth fully, or difficulty eating and drinking.
Toxin or irritant exposure
Contact with or ingestion of irritant substances can produce sudden, often profuse drooling. Certain plants, cleaning products, insects, toads and chemical irritants can stimulate intense salivation; in the UK, a dog or cat that mouths a common toad typically drools profusely or froths at the mouth. The drooling typically has a very acute onset and may be accompanied by pawing at the mouth, retching, or oral redness. Drooling together with tremors, twitching, a high temperature or seizures can point to a poison acting on the whole body rather than a local irritant: slug pellets containing metaldehyde, for example, cause signs in dogs from 30 minutes to 6 hours after eating, and death can follow within 4 to 24 hours.
Why timing matters
Early observation
When new or increased drooling is first noticed, it may appear as damp patches around the mouth, wet spots on bedding, or visible saliva strands that were not previously typical for the individual animal. Some drooling around mealtimes, during excitement, or in warm weather is normal for many breeds, so the significance lies in whether the drooling represents a change from the animal's baseline. The exception is heavy drooling with heavy panting, weakness or collapse in hot conditions, which are signs of heatstroke, a life-threatening condition. Early new-onset drooling may be intermittent, occurring in specific contexts such as during car journeys, when presented with certain foods, or at particular times of day. In cats, any visible drooling tends to be more notable as cats typically produce less visible saliva than dogs.
Later presentation
Drooling that becomes persistent, increases in volume, or changes in character (becoming thicker, blood-tinged, or foul-smelling) may suggest an established oral, neurological, or systemic condition. Sustained drooling can lead to secondary effects including skin irritation around the mouth and chin, staining of the fur, and moisture-related skin infections in the lip folds. Animals with persistent drooling may also show concurrent changes such as reluctance to eat, difficulty swallowing, pawing at the mouth, or a change in breath odour. The development of these additional signs alongside worsening drooling often provides important context about the underlying cause.
The trajectory of drooling depends on its cause. Nausea-related drooling tends to be episodic, correlating with the stimulus that provokes it. Oral disease typically produces gradually worsening drooling as the condition progresses, with the volume increasing and potentially becoming malodorous as dental disease advances or masses enlarge. Neurological causes may produce drooling that develops relatively suddenly and persists consistently. Foreign body-related drooling often has an acute onset and may worsen as tissue irritation or infection develops around the lodged object. Seasonal patterns of drooling may suggest environmental triggers such as plant exposure or insect stings.
Conditions commonly associated
Dental Disease in Dogs
Dental disease irritates the gums and surrounding tissue, and the resulting oral pain and inflammation stimulate excess saliva production, so drooling often increases as the condition progresses.
Dental Disease in Cats
Inflamed gums and diseased teeth trigger increased saliva production and discomfort when chewing, and because cats mask pain well, drooling can be one of the more noticeable signs of underlying dental disease.
Gastric Dilatation-Volvulus (GDV) in Dogs
Profuse drooling (hypersalivation) accompanies GDV as the dog experiences intense nausea from gastric distension while being unable to vomit effectively.
Hepatic Lipidosis in Cats
Drooling may be observed in cats with hepatic lipidosis, where it may reflect nausea or hepatic encephalopathy, a disturbance of brain function caused by the failing liver.
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Stomatitis in Cats
Profuse drooling is a hallmark sign of feline stomatitis, resulting from severe oral pain and inflammation that stimulates excessive saliva production while making normal swallowing uncomfortable.
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Epilepsy in Cats
Excessive salivation or drooling may accompany seizure activity in cats with epilepsy, sometimes being one of the more obvious signs of a focal seizure.
Foreign Body Ingestion
Drooling may occur with foreign body ingestion, particularly when objects are lodged in the mouth, throat, or oesophagus, or when pets are nauseated from gastric or intestinal obstruction.
Periodontal Disease
Excessive salivation can occur with oral pain or difficulty swallowing associated with dental disease.
Hepatic Lipidosis
Excessive salivation may occur due to nausea or early hepatic encephalopathy.
Feline Stomatitis
Severe oral inflammation can cause excessive salivation, sometimes blood-tinged, as swallowing becomes painful and the inflamed tissues produce excess secretions.
Tooth Resorption
Oral discomfort from resorptive lesions may stimulate excess saliva production, sometimes tinged with blood.
Oral Squamous Cell Carcinoma in Cats
Oral squamous cell carcinoma can ulcerate and become painful, leading to increased or blood-tinged saliva pooling at the mouth.
Hepatic Encephalopathy
Drooling is one of the recognised signs of hepatic encephalopathy, alongside the altered mental state, dullness, head pressing and wandering, as the failing liver disturbs brain function.
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Salivary Mucocele
A mucocele under the tongue (ranula) can be injured and bleed, and one in the throat (pharyngeal mucocele) can impair normal swallowing and obstruct the airway, so saliva may pool and drool.
Oral Melanoma
A mass growing in the mouth can interfere with normal swallowing and comfort, leading to more saliva pooling and drooling than usual.
When to explore further
New or increased drooling that persists for more than a day or two without an obvious transient cause (such as motion sickness or brief nausea) may warrant closer attention, particularly if it represents a clear change from the animal's normal baseline.
Drooling accompanied by changes in eating behaviour (reluctance to eat, dropping food, chewing on one side, or preferring soft food over hard) suggests oral pain or dysfunction that may benefit from oral examination.
Blood-tinged or foul-smelling drool adds important context, as these characteristics may indicate tissue breakdown, infection, or significant oral pathology rather than simple overproduction of saliva.
Sudden onset of profuse drooling, particularly if accompanied by pawing at the mouth, gagging, or distress, may suggest a foreign body, toxin exposure, or acute oral injury; when tremors, twitching or seizures are also present, a poison affecting the whole body is a concern.
Drooling in combination with difficulty swallowing, a changed voice, noisy breathing, or regurgitation may indicate involvement of the pharyngeal or laryngeal regions rather than a purely oral cause, and noisy or laboured breathing alongside drooling can mean a swelling, mass or foreign body is narrowing the airway.
In a dog, drooling together with retching that brings nothing up, restlessness, and a swollen or tight abdomen fits gastric dilatation-volvulus (GDV), a rapidly progressive, life-threatening twisting of the stomach seen most often in large, deep-chested breeds; it cannot be ruled out at home and survival depends on treatment that includes surgery. About 15 to 20% of dogs that have surgery still die. In UK out-of-hours practices only about half of dogs presented alive with GDV survived to discharge, and outcomes are worse when signs have been present for more than 6 hours.
Noting whether the drooling is new or increased compared to the animal's normal baseline, whether it is constant or episodic, and whether it has a particular character (clear, thick, blood-tinged, malodorous) can help identify patterns. Observing whether the drooling correlates with specific activities such as eating, travelling, or excitement, and whether it is accompanied by other oral or systemic signs, may provide useful context.
Last reviewed: 10 October 2026 · Dr Alastair Greenway MRCVS