Infectious stomatitis of the frilled lizard (rotten mouth)
Infectious stomatitis, often called "rotten mouth", is an infection of the frilled lizard's mouth. \nIt affects the gums and the inside of the mouth. \nOpportunistic bacteria take advantage of a small injury or weakening of the animal to de...
What is it?
Infectious stomatitis, often called "rotten mouth", is an infection of the frilled lizard's mouth. \nIt affects the gums and the inside of the mouth. \nOpportunistic bacteria take advantage of a small injury or weakening of the animal to develop. \nIf left untreated, the infection can spread to the jaw bone and become serious.
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:
There is a yellowish or whitish deposit inside the mouth, resembling curdled cheese. \nThe gums are red, swollen, sometimes bleeding. \nThe lizard drools more than usual and may refuse to eat due to pain. \nIn advanced forms, the mouth remains ajar, an unpleasant odor is released, and swelling of the jaw may appear. \nThe animal becomes despondent and loses weight if the infection lasts.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
Stomatitis is almost always caused by bacteria already present in the lizard's mouth, which become pathogenic when the animal is weakened or injured. \nA small wound caused by live prey, a fall, or friction against the terrarium decor can be enough to open the door to infection. \nChronic stress, poor diet or unsuitable temperature also weaken the animal's natural defenses.
The main contributing factors are unsuitable temperature or humidity in the terrarium, a lack of exposure to UVB, a diet poor in vitamins, a poorly cleaned terrarium, and stress linked to too small a space or to cohabitation with other animals. \nAn immune system already weakened by another illness also increases the risk.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
The veterinarian examines the lizard's mouth, sometimes under light anesthesia to clearly visualize the lesions. \nA sample can be taken to identify the bacteria in question and guide the choice of treatment. \nAn x-ray may be suggested if damage to the jaw bone is suspected.
Treatment
Treatment is based on local cleaning of the lesions, the application of oral antiseptics, and often a general antibiotic treatment prescribed by the veterinarian. \nCorrection of breeding conditions (temperature, UVB, diet) is an integral part of the treatment. \nNutritional support may be necessary if the animal no longer eats on its own.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Maintaining a temperature and humidity adapted to the species is essential. \nQuality UVB lighting, renewed regularly, helps prevent deficiencies. \nProviding a varied and appropriate diet, cleaning the terrarium regularly, and avoiding abrasive or sharp decorations limits oral injuries. \nRegular veterinary check-ups help spot the first signs before they get worse.
Possible complications
Without treatment, the infection can spread to the jaw bone, causing osteomyelitis that is difficult to treat. \nIt can also spread to the respiratory tract or pass into the blood, threatening the life of the animal. \nTooth loss or jaw deformity is possible in severe and long-standing cases.
When to see a veterinarian
Presence of an unusual whitish or yellowish deposit in the mouth.
Excessive salivation or mouth hanging open.
Refusal to eat for more than a day or two.
Visible swelling of the jaw or face.
Marked depression associated with these oral signs.
Prognosis
The prognosis is good if stomatitis is treated early and breeding conditions are corrected. \nIt becomes more reserved in the event of bone damage or delay in treatment, with a risk of after-effects or relapses.
Frequently asked questions
Is rotten mouth contagious between lizards?
The risk of direct transmission is low, but a poorly cleaned terrarium or shared equipment can encourage the spread of the responsible bacteria between several animals.
Can I treat my lizard alone with an antiseptic purchased without veterinary advice?
No. Inadequate cleaning or poorly chosen treatment can mask the signs without curing the infection, giving it time to spread to the jawbone.
Can my lizard continue to eat on its own?
It depends on the pain felt. If the animal refuses to eat, appropriate dietary support may be necessary, to be discussed with the veterinarian.
How long does the healing take?
Stomatitis caught early often heals within a few weeks with appropriate treatment, but advanced forms with bone involvement require much longer follow-up.
References
AVMA — American Veterinary Medical Association
Content reviewed by the TunisieVet editorial team · Updated 28 September 2026
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