Urolithiasis in a 25 Year Old Sulcata Tortoise
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A 25 year old male Sulcata tortoise (Geochelone sulcata) was presented to the Cornell University Hospital for Animals (CUHA) Exotics Service on 08/03/2017 for evaluation and removal of a large urolith (bladder stone). On 05/17/2017 the patient passed a 2.5 inch (6.4 centimeter) diameter stone, through his cloaca and phallus. He was taken to his primary veterinarian who performed radiographic evaluation of the patient’s coelomic cavity, revealing a second, larger stone (approximately 3 inches or 8 centimeters in diameter), sitting within the right lobe of his bladder. Analysis of the passed stone revealed a uric acid composition, which is the most common urolith of chelonians. On presentation to the CUHA Exotics Service, methods of stone removal were discussed with the owner including breaking down the stone via endoscopy or, should that method be ineffective, surgical removal. The patient’s physical exam was unremarkable except for moderate pyramiding of his shell and overgrowth of his caudal scute. The patient was sedated with an intramuscular injection of ketamine and dexmedetomidine, then intubated and maintained under anesthesia with isoflurane. Complete blood count and chemistry panels returned with no significant abnormalities. His caudal scute was cleaned and prepped in a sterile fashion, then trimmed and filed with a Dremel in order to give more access to his cloacal opening. On endoscopic exam, a small area of inflamed tissue was noted which could have been due to irritation caused by the stone, or by movement of the endoscopy equipment. Neither the opening into the bladder, nor the stone itself, could be well visualized so the procedure was discontinued and the patient recovered from anesthesia. Recovery was long, but not uncommon for reptile patients. During the procedure, there were some concerns regarding the patient’s cardiac stability while under anesthesia, so caution was recommended for any future anesthetic events. The owner chose to monitor the patient rather than pursue further endoscopic or surgical treatment. Uric acid urolithiasis in reptiles, including chelonians, is common and well described in the literature. Tortoises usually form uric acid stones, which can occur if their urine is supersaturated with uric acid, which then begins to crystalize. Many small crystals form, then clump and stick together, continuing to grow until the concentration of uric acid decreases to the point that no more crystals can form. Uroliths can form in the bladder, ureters, and/or cloaca. The formation of these stones is multifactorial, including genetic predisposition, variations in the structure of the urogenital organs, and nutrition. This report will discuss chelonian urogenital anatomy, the mechanism of the formation of uric acid uroliths in chelonians, the complications that uroliths can pose, as well as surgical and endoscopic treatment options.