Superficial shell abscesses and erosions, or shell rot as it is often called, is a common problem in aquatic chelonians. The keratin scutes that cover the bony shell develop defects or develop dark, pale or pink discolorations. The problem usually occurs as a result of infrequent water changes, lack of a filtration system, filtration system not cleaned and/or too low an environmental temperature.
Besides correction of the husbandry, treatment begins with the removal of any loose scute material along with underlying dead tissue. The blunt end of a scalpel blade works well. If, when scraping, the underlying tissue is bleeding, pieces of bone are becoming loose, cheesy material is present or the turtle is painful then the shell abscess is likely deep and further treatment should be done under sedation by a veterinarian. After complete removal of loose and dead tissue we have had excellent results with a product called Tricide-Neo. It is available from many sources including www.koiacres.com. After re-constituting the powder, sponge onto the affected areas and leave moist for 15-20 minutes. Use four times daily for two weeks and then twice daily until lesions are completely healed. You can use the solution for one week before changing to new solution. The shell is healed when it is free of discharge and odor, and is “smooth” (irregular scars may remain for life).
I don’t recommend dry docking which can result in decreased food and water intake. Antibiotics given as injections or orally should be reserved for deep shell abscesses and will not correct the problem without removing the loose and dead tissue. Frequent complete water changes 2-3 times per week for a 10 gallon tank and once weekly for a 50 gallon is best. Scrub tank and filter with 1 part bleach to 5 parts water and then rinse well. Feeding in a separate container will help keep the tank clean also. Water temperature and basking sites need to be at appropriate temperatures.