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What is Ulcerative Shell Disease?

Ulcerative shell disease occurs in two main forms: the dry form is usually connected to a fungal infection and the wet form is linked to gram negative bacteria. The disease will typically occur after the shell is injured. Even minor injury to the turtle’s shell can lead to the disease; should there be any penetrating damage to the shell, bacteria, fungus or other pathogens are able to enter into the living tissue just below its outer hard layer. Also called shell rot, the ulcers that are present may be superficial or deep and can become infected.

SCUD (Septicaemic Cutaneous Ulcerative Disease) is also mentioned in connection with ulcerative shell disease; this is a serious condition where bacteria are growing in the bloodstream. SCUD can be fatal as the pathogens are distributed by the blood supply and can start attacking your turtle’s organs. Systemic antibiotics are necessary for your turtle to recover.

Ulcerative shell disease occurs when there is damage to a turtle’s shell, leading to a fungal or bacterial infection.

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Symptoms of Ulcerative Shell Disease in Turtles

Should your turtle be experiencing ulcerative shell disease, you will notice that his shell does not look even and that its plates may lift. You may also see a discharge under his shell that has a terrible smell. Pitting of the shell may be seen and in particularly bad cases, parts of your turtle’s shell may fall off. When this happens the bone may be seen underneath his shell; the bone can be healthy or may be diseased if he has had the condition for a long time. 

In SCUD, the scutes show pitting. Your turtle may be disinterested in eating and lethargic and you may notice petechial hemorrhages on the shell and his skin. Liver necrosis may also occur.


Ulcerative shell disease may be simple “shell-rot” or the more severe SCUD. Ulcerative shell disease is seen in two main forms: 

  • Dry form: Usually connected to a fungal infection 
  • Wet form: Linked to gram negative bacteria and will typically occur after the shell is injured.

SCUD is a very serious condition that can quickly lead to death in your turtle.

Causes of Ulcerative Shell Disease in Turtles

Ulcerative shell disease can occur when there is an injury, whether the result of a fight or other behavior, or the conditions of your turtle’s environment providing the opportunity for bacteria, fungus or algae to get into the shell and cause an infection. Ticks can also cause small breaks in the shell of your turtle which can let bacteria or fungus in. The bacteria Citrobacter freundii is often responsible for SCUD, though there are other bacteria that have been isolated in this condition.

Diagnosis of Ulcerative Shell Disease in Turtles

Should you notice any injury to your turtle’s shell, you will want to have him examined by your veterinarian. In addition to conducting a physical examination of your turtle, your veterinarian may ask you questions about his history as well as the environment where he resides, including whether other turtles share it with him. Your veterinarian will look closely at your turtle and conduct tests based on what he sees during the physical examination. These can include a cytology of the lesions, bacterial and cultural sensitivity testing, fungal isolation and blood testing (to include a complete blood count and plasma chemistries). 

Once your veterinarian has determined the cause of the disease in your turtle, treatment should begin immediately; the longer the infection goes untreated, the greater chance that the infection will become systemic or your turtle will experience an ulcerating abscess in his bony tissue. 

Treatment of Ulcerative Shell Disease in Turtles

Should your turtle have the dry form of ulcerative shell disease, he will require treatment with an antifungal medication. Should he develop the wet form, your veterinarian will remove the scute that is infected and use a diluted Betadine solution to irrigate the area, as well as apply a topical antibiotic. 

If your turtle is diagnosed with SCUD, systemic injectable antibiotics may be necessary and should be administered right away. Even with immediate treatment, the long term prognosis will be guarded.

Treatment may include daily or twice daily cleaning of the shell with the removal of any dead tissue. A povidone-iodine or chlorhexidine solution can be used for the cleaning and should be completely rinsed after being applied. Should your turtle have deep ulcers, they may need to be surgically repaired and acrylic or fiberglass material may need to be applied. The area of the shell that has been affected should be kept dry and air should be able to circulate.

Recovery of Ulcerative Shell Disease in Turtles

Should your turtle experience ulcerative shell disease, careful follow-up will be necessary. You and your veterinarian will want to monitor your turtle and his shell to make sure that his condition is improving. 

Your veterinarian will likely recommend that you take a good look at your turtle’s environment. The initial injury to his shell may have been due to rough walls or flooring in his environment; these should be resolved to avoid future injury. Make sure that your turtle is kept in an environment that is kept at the appropriate level of humidity. Should it be too dry, his shell can crack, which will allow bacteria and fungi to enter. If there is too much humidity the shell can soften and the plates may lift up, which can also let organisms in. It is imperative that the environment where your turtle resides be clean.