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Infectious stomatitis of monitor lizards (rotten mouth)
Infectious stomatitis, often called "rotten mouth", is an inflammation of the lining of the mouth affecting reptiles, including the Komodo dragon. It results in lesions, swelling of the gums and sometimes pus. In this species, often kept in...
What is it?
Infectious stomatitis, often called "rotten mouth", is an inflammation of the lining of the mouth affecting reptiles, including the Komodo dragon. It results in lesions, swelling of the gums and sometimes pus. In this species, often kept in captivity in zoological parks or conservation centers, the disease must be treated quickly because it can progress to a deep infection of the bone and neighboring tissues.
It is frequently linked to a general weakening of the animal, chronic stress or a pre-existing oral injury.
Key point
Untreated stomatitis can progress to a serious bone infection and jeopardize the survival of the animal, particularly in the context of conservation programs where each individual counts.
Commonly observed signs
These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.
Related signs — each one links to its page:
The first signs are discreet: the animal salivates a little more than usual and eats less willingly.
Looking at the mouth, we can see redness, small whitish or yellowish deposits resembling cheese, or even small sores on the gums or palate.
A bad smell often comes from the mouth.
At a more advanced stage, the gums swell, teeth may become loose, and the animal has difficulty grasping or chewing its prey.
The Komodo dragon then becomes despondent, loses weight and may refuse all food.
In severe forms, the infection can spread to the jaw bone, causing visible deformity of the muzzle.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
Infectious stomatitis most often results from an proliferation of bacteria normally present in the reptile's mouth, which become pathogenic when the balance is disrupted. Opportunistic bacteria (especially Gram-negative species) are commonly involved.
A small oral injury, caused by live prey, a hard object in the terrarium or a fight between conspecifics, often opens the door to infection.
An immune system weakened by stress, unsuitable breeding temperature, or an underlying disease also favors its appearance.
The main contributing factors are: insufficient hygiene of the enclosure, poorly controlled temperature or humidity, a diet deficient in particular in vitamins, chronic stress linked to captivity or cohabitation with other individuals, and repeated oral injuries when taking prey.
Old, sick or recently transported animals are more vulnerable.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
The veterinarian performs a careful examination of the mouth, sometimes under light sedation as long as the animal is large and powerful. He or she can take a sample of the lesions to identify the bacteria involved and guide treatment.
X-rays may be needed to check if the infection has reached the jaw bone.
A blood test allows you to assess the animal's general condition and look for an underlying cause.
Treatment
Treatment generally combines local cleaning of the lesions with antiseptic products suitable for reptiles, and antibiotic therapy chosen according to the bacteria identified.
Nutritional support may be necessary if the animal eats little, as well as rehydration care.
In cases where the bone is affected, surgery to remove infected tissue may be considered.
Improving breeding conditions is an integral part of the treatment.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Prevention is based above all on suitable breeding conditions: temperature and humidity corresponding to the needs of the species, clean and regularly disinfected enclosure, absence of objects that could injure the mouth.
A balanced and varied diet, including the necessary supplements, strengthens the animal's natural defenses.
Regular veterinary check-ups, including examination of the oral cavity, help identify lesions before they become seriously infected.
Limiting stress and aggressive contact between individuals also helps reduce the risk.
Possible complications
Without treatment, the infection can spread to the jaw bones (osteomyelitis), cause tooth loss, or even spread into the bloodstream and affect other organs.
Severe weight loss and general weakening can be life-threatening.
When to see a veterinarian
The animal salivates more than usual or refuses to eat.
A bad odor or abnormal deposits are visible in the mouth.
The gums are swollen, red, or bleed easily.
The animal has difficulty grasping or chewing its food.
Unusual weight loss or depression is observed.
Prognosis
The prognosis is good if the disease is detected and treated at an early stage.
It becomes more reserved when the infection has reached the bone or has become widespread, requiring longer treatment and sometimes surgery.
Regular veterinary monitoring after treatment is recommended to avoid recurrence.
Frequently asked questions
Is infectious stomatitis contagious between Komodo dragons?
It is not directly contagious like the flu, but bacteria can be transmitted through bites or contact with contaminated equipment. Isolating a sick animal is a useful precaution.
Can this disease be treated without a veterinarian?
No. Local cleaning alone is not enough if deep-seated bacteria are involved. A diagnosis and appropriate treatment by a veterinarian specializing in reptiles are essential.
Does this disease only affect Komodo dragons?
No, it is seen in many reptiles, including other monitor lizards, snakes and lizards, especially in captivity.
How long does the treatment last?
It depends on the severity of the lesions. Mild forms heal in a few weeks, while bone damage requires much longer follow-up.
References
AVMA — American Veterinary Medical Association
Content reviewed by the TunisieVet editorial team · Updated 11 August 2026
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This information is provided for educational purposes only and is not a substitute for a veterinary consultation. If you have any concerns about your animal's health, consult a veterinarian.
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