Drooling / Excess Salivation / Ptyalism

Chronic wetness under the chin
If a rabbit’s skin is chronically exposed to moisture, then baldness, redness, and crusting may develop, and bacterial infection may follow. Infection by the bacterium Pseudomonas aeruginosa sometimes causes a moist dermatitis which shows as a blueish discolouration of the fur. If drinking water is contaminated with Pseudomonas, rigorous disinfection or replacement of water containers is essential. Daily care of the affected area is necessary and may include clipping, cleansing with chlorhexidine or tamed iodine solution, and applying topical antibiotic/anti-inflammatory powder or ointment. Intensive or prolonged use of topical corticosteroids can have systemic effects and should be avoided. Systemic antibiotics (based on culture/sensitivity testing) are needed if there is pus, fever, or lethargy. 

In some rabbits, fur loss is restricted to the area just under the chin, in the folds of the dewlap (the fleshy flap of skin and tissue under the skin), or down the chest. Often, but not always, the fur and/or skin there will be wet. In many, but not all cases, the rabbit will also develop suddenly picky eating habits. These can vary greatly among individuals, with some rabbits being willing to eat pellets, but not hay, others eating hay but not pellets, some refusing to drink, and still others refusing everything but the most favourite treats. In short, any change in eating preferences is usually a good enough reason for a dental exam by an experienced rabbit vet. Dental problems such as molar spurs can make the bunny drool. Since saliva is caustic, it burns the skin, making the wet area itchy and sore, and causing the fur to fall out. Some rabbits will actually chew at the irritated area so much that they develop open sores.

Differential Diagnosis of Ptyalism

Ptyalism can include both acute drooling and chronic drooling. In each case, the cause of excessive production of saliva is different.

Acute ptyalism can typically be caused by -

• Epiglottitis (Epiglottitis is inflammation of the epiglottis—the flap at the base of the tongue that keeps food from going into the trachea/windpipe.

• Neoplasia (abnormal growth of tissue in a part of the body, especially as a characteristic of cancer) or the presence of a tumour

• The Presence of an abscess

• Pain

• Heat stroke

Chronic ptyalism can typically be caused by -

• Neurologic trauma (e.g., stroke)

• Medication (analgesics, anticonvulsants etc)

• Obstruction in the nasal cavity (e.g., presence of polyps)

• Size of the tongue

• Position of the head

• Sitting or lying position

• Stress

• Diseases, e.g. tetanus

Other causes can be related to -

Dental issues : 

• Tongue or cheek ulcers caused by molar spurs.

• Tooth root abscess

• Inflammation of the tongue

• Cheek abscess

Oral or Gastro-intestinal Issues:

• Oral ulcerations

• Epulis, (tumor or growth on the gum)

• Stomatitis (inflammatory condition of the mouth, resulting from infection by bacteria, viruses, or fungi, from exposure to certain chemicals or drugs, from vitamin deficiency).

• Bloat, or an abnormal collection of gas in the stomach, or cecum. In this case the stomach feels swollen and the rabbit is in pain.

• Gastroesophageal reflux

• Gastric distension

• Acute gastritis (inflammation of the lining of the stomach), caused by surgery, aspirin or other drugs, by food allergens or by the presence of viral, bacterial, or chemical poisons

• Pancreatitis (e.g., presence of gallstones, infection or medication)

• Digestive organ failure (e.g., liver disease)

Respiratory issues:

Inflammation of the pharynx, bronchia and lungs (e.g., alveolar abscess)

Pharyngitis (inflammation of the pharynx), where the compromise passage of air can lead to respiratory distress, and one symptom, among others is drooling.

Cardiovascular issues:

• Portosystemic shunts, a congenital or acquired vascular abnormalities that permit portal blood flow to bypass the liver and enter the systemic circulation directly. In small animal, this is characterized by drooling.

Food:

• Nutrient deficiency, e.g., folate deficiency, chronic fluorosis, subacute scurvy

Mechanical issues:

• Presence of a trapped foreign body between molars (e.g., hay, fur)

• Overgrowth of the crown of the tooth (e.g., presence of spikes)

• Malocclusion of the front teeth

• Odontoclastic lesions (small to large enamel defects right at the gum line)

• Broken tooth

• Broken maxillary bone

• Wounded or lacerated tongue and/or gums

Nervous Issues:

• Stress

• Pain

Toxicity:

• Medication

• Toxins

• Poisoning

Source: Differential Diagnosis for Ptyalism (excessive production of saliva, drooling, slobbering) - MediRabbit

What is Excessive Salivation/Ptyalism?
Rabbits who have ongoing saliva production, irritated fur and skin, and are losing weight may have a condition called ptyalism. This is more than typical saliva that will come from your rabbit during eating, drinking or grooming. This excessive salivating will last more than a few isolated minutes and may begin to impact his health and appearance.

There are many possible causes of excessive salivation in your rabbit such as overheating and misaligned teeth. If you see that your rabbit is displaying signs of hypersalivation and possible discomfort, seek help from your veterinarian. Ptyalism is defined as the excessive production of saliva in rabbits. Dental disease is thought to be one of the main reasons for excess salivation.

Symptoms of Excessive Salivation in Rabbits -

You may notice your rabbit beginning to show signs and symptoms of excessive salivation. These symptoms may present over time and your rabbit may exhibit some but not all of the symptoms identified below. Some things to watch out for and be mindful of are:

• Excessive production of saliva

• Hair loss around their mouth or dewlap

• Thickened skin folds

• Wet fur and/or irritated skin

• Lack of grooming

• Decreased appetite

• Weight loss Signs of pain/discomfort

• Teeth grinding

• Lethargy

• Nasal discharge

Causes of Excessive Salivation in Rabbits

There are many things that may lead your rabbit to experience excessive salivation. One of the large categories is dental. Some breeds of rabbits tend to have a higher rate of developing dental concerns and those include lop eared and dwarf rabbits. If your rabbit has a family history of dental diseases or concerns, he is also at a higher risk of developing dental issues. Rabbits that do not eat a large amount of hay or grass tend to have higher incidents of dental problems also. Lastly, if your rabbit has had any trauma or injury to their teeth, he could be at an increased danger of having dental concerns. 

Dental Causes

• Malocclusion of teeth (overgrown teeth) – genetic, trauma or infection of teeth 

• Infections of the teeth

• Split or fractured teeth

• Abscesses inside your rabbit’s mouth/gums

• Molar spurs

• Gingivitis

• Stomatitis

Another cause of excessive salivating in your rabbit may be due to an underlying medical concern. This is rare, however, it is possible.

Medical Conditions

• Respiratory problem

• Pneumonia 

• Neurological disorders that can cause facial paralysis

• Central/nervous system disorders

Other Causes

• Food stuck in his teeth

• Bitter or bad tasting food

• Ingestion of toxic substance

• Burn from chewing through wires/electrical cords

Diagnosis of Excessive Salivation in Rabbits

If you are concerned that your rabbit may be suffering from excessive salivation, a call and visit with your veterinarian should be your next step. When visiting with your rabbit’s veterinarian she will want to look at the inside of his mouth and may choose to do this while your rabbit is under anesthesia. The veterinarian will check for any obvious issues that would be causing the salivation – injured tooth, abscessed, overgrown teeth, something stuck in his teeth, etc.  Your veterinarian will ask for a history of your rabbit’s health, family history if possible, and any concerns or issues you have noticed. It is important to identify any and all concerns you have noticed with your rabbit to discuss these and share them with your veterinarian to help make a diagnosis. Some things to keep in mind are any recent changes to your rabbit’s diet, any trauma or injury he has sustained, and environmental changes. Your veterinarian may request further testing to be done such as CT scans and X-rays. These tests will better help the veterinarian to pinpoint any abscesses, infections or similar things that may be causing your rabbit’s issues. Blood tests are possible to check for any underlying diseases that the excessive salivation may be a symptom of as well.

Treatment of Excessive Salivation in Rabbits

Treatment will vary and largely hinge on what is causing your rabbit’s excessive salivating. Depending on your veterinarian’s findings, the course of treatment will be specific to your rabbit’s issues. If your rabbit is found to have an infection, antibiotics may be prescribed. The antibiotics can be oral, an injection, or other methods your veterinarian will discuss with you. An infection of the tooth could result in an extraction of the tooth or teeth. If the concern is regarding your rabbit’s teeth being overgrown, the veterinarian may suggest bringing him in on a regular basis to have his teeth trimmed down. However, the veterinarian may also want to discuss extraction of the teeth as rabbits are known to not do well with pain management. Recovery of Excessive Salivation in Rabbits

A change in diet may also be suggested for your rabbit to ensure ongoing proper dental hygiene and prevent continuing of overgrown teeth. Diet changes may include providing a large supply of hay/grass, leafy greens and an avoidance of an all pellet based diet. Having safe chewing objects for your rabbit can also help with proper wear of his teeth. Be cautious to avoid treated, painted, or varnished wood however.  Periodically checking your rabbit’s teeth and mouth is also beneficial to notice any changes sooner rather than later. Regular visits with your veterinarian are encouraged as well and keeping up with any changes to your rabbit between visits. Chronic dental disease will call for lifelong treatment and care for your rabbit.
Source: Excessive Salivation in Rabbits - WagWalking

Further Reading:
Excessive Salivating in Rabbits - PetMD