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Scale Rot - Necrotizing (Ulcerative) Dermatitis

Ulcerative dermatitis (Scale Rot - Necrotizing Dermatitis) is often seen in snakes and lizards that are housed in unhygienic conditions with excessive humidity and moisture.

Scale Rot - Ulcerative Dermatitis

Ulcerative dermatitis (necrotic dermatitis - scale rot) is often seen in lizards and snakes who are being kept in unhygienic conditions, with excessive humidity and moisture. Overly moist environments, where fecal matter or food is present, promotes bacterial and fungal growth which can lead to skin erosion - degradation. Long term exposure to these unhygienic conditions can lead to infections and septicemia, which can lead to death.

Scale Rot Causes

The primary cause for scale rot is unhygienic living conditions where bacteria has had the ability to manifest. This is typical in habitats where excessive moisture is present along with feces and food items. Warm humid conditions allow bacteria to reproduce, which in turn affects the animal living on it. This is not always the case however. Even animals kept in pristine conditions can develop ulcerative dermatitis from skin injuries that bacteria has entered through. A deficiency in vitamins A and C have also been noted as a cause in certain circumstances. It has also been associated with parasitism (internal and external), as well as "stress". (Branch et al., 1998)

Scale Rot
Ball Python - Bad Scale Rot

Scale Rot Signs

This disease can present itself in several ways, so attention should always be made to your reptiles physical appearance since early detection makes treatment much easier, faster and less expensive. This disease commonly affects snakes and lizards and may display itself as discolored scales, presenting as browns, yellows, reds and even greenish-black on the ventral surface of the animal. (They can also be found in other areas, like the tail region, though it is common to see the locations that have the most contact with the substrate.). You may see raised scales that didn't exist before, where blood could have pooled beneath them. Blisters are not uncommon and are also typically found on the ventral surface, where contact with the bedding is most consistent. You could have swelling and soft tissue where fluid discharge is released. If you see what appears to be a burn, it could be subcutaneous tissue that has been exposed through sloughing, damaged scales from swelling or from blisters that have ruptured, damaging the skin beneath them.

How Is Scale Rot Diagnosed

A history will be taken on the animal and a visual inspection of the animal will be done (clinical examination). Blood work will determine the exact bacteria that needs treating.[1] Aeromonas and Pseudomonas are particularly common isolates, but others that have been isolated include Flavobacterium, Staphylococcus and Morganella, and sometimes anaerobes such as Bacteroides, Fusobacterium, and Clostridium spp. Open wounds will be cleaned and may be swabbed for cultures. Sensitivity tests will likely be performed. Aseptic sampling of unburst blisters may be performed for testing purposes also.

Scale Rot Treatment

Treatment will include topical or systemic antibiotics to destroy the bacteria with some cases requiring both. Debridement may be necessary on open wounds to cleanse away dead tissue and to deep clean the infected tissue. Adhesive draped may be required to keep ointments on and bacteria and dirt out. It will require you to house your reptile in a quarantine type set-up while the animal heals. You will need to completely empty the previous enclosure, discarding all of the bedding and thoroughly cleaning everything with a 5% bleach solution to eradicate the existing bacteria in the enclosure and on items inside. Fluids may need to be administered orally in some cases. Keeping the animal dry and clean will speed the process up.

Scale Rot Prevention

Proper husbandry will have prevented the vast majority of scale rot cases that have been seen. You need to keep the enclosure clean of feces and excessive moisture. Food items that are left in damp conditions are breeding grounds for bacteria. Proper husbandry is often the solution to prevention. If your animal has injured its skin somehow, it is a good practice to keep them in a quarantine set-up until they have healed. An open wound can come into contact with fresh feces and bacteria can then manifest itself. Some of the cleanest animals can get scale rot, so pay close attention for the signs so that you can seek treatment immediately.


Author: Richard Brooks
[1] Mader, Reptile Medicine and Surgery, Second Edition 2006 pgs. 205
Mader, Reptile Medicine and Surgery, Second Edition 2006 pgs. 205,213
Leonard C. Marcus, Veterinary Biology and Medicine of Captive Amphibians and Reptiles, 195