Infectious stomatitis, commonly called mouth rot, is a bacterial infection of the oral tissues that can affect any reptile but is especially common in snakes, bearded dragons, iguanas, and chameleons. What begins as mild gum inflammation can progress through tissue necrosis, bone involvement, and systemic infection if left untreated. It is almost always secondary to an underlying stressor or husbandry problem.

Causes

Mouth rot rarely appears in well-maintained, healthy reptiles. Suboptimal temperatures that suppress immune function are the most frequent underlying factor. Oral trauma from rubbing against rough cage surfaces, biting hard prey, or substrate lodged between teeth creates entry points for bacteria. Chronic stress, malnutrition (particularly vitamin C deficiency in some species), and overcrowding contribute. The bacteria involved are typically normal oral flora that become opportunistic when defenses are lowered.

Stages of progression

In the early stage, the gums appear redder than normal and slightly swollen. A thin line of mucus or tiny petechiae (pinpoint bleeds) may be visible along the gum line. In the moderate stage, yellowish or cheesy plaques (caseous exudate) form on the gums, palate, or tongue. The reptile may show decreased appetite and increased saliva. In the advanced stage, tissue dies and falls away, exposing bone. The jaw may become soft or deformed. Systemic infection causes lethargy, swelling of the head, and sepsis.

When to seek veterinary care

Any visible oral abnormality, pus, or behavioral change around feeding warrants a veterinary visit. Do not attempt to remove plaques at home, as this can worsen tissue damage and spread infection deeper. Early-stage cases respond well to treatment; advanced cases carry a significantly worse prognosis and may require weeks to months of care.

Treatment

The veterinarian will debride infected tissue, flush the oral cavity with antiseptic, and prescribe systemic antibiotics based on culture and sensitivity results. Pain management is critical; untreated pain suppresses appetite and slows healing. Topical antibiotic or antiseptic rinses applied at home may be part of the treatment plan. Advanced cases may need repeated debridements under sedation and nutritional support via syringe feeding.

Prevention

Maintain correct temperature gradients and verify them with a reliable thermometer. Eliminate rough surfaces and sharp objects in the enclosure. Feed appropriately sized prey and remove uneaten live prey that may bite the reptile. Ensure a balanced diet with adequate vitamins. Inspect your reptile’s mouth during routine handling and address any redness or unusual discharge early.

Veterinary disclaimer: This article is for general education only and does not replace an examination by a licensed reptile veterinarian. If you notice oral lesions or pus in your reptile’s mouth, consult a vet promptly.