Canine Cushing's Case Files: The ins and outs of detection and treatment—Case file: Libby (Sponsored by Dechra Veterinary Products)

Canine Cushing's Case Files: The ins and outs of detection and treatment—Case file: Libby (Sponsored by Dechra Veterinary Products)

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Nov 01, 2013

Case file: LIBBY
12-year-old spayed female toy poodle weighing 5.3 lb (2.4 kg)

Patient history and initial diagnostic workup


Todd M. Archer, DVM, MS, DACVIM
Libby was presented to her primary care veterinarian for a dental prophylaxis. Libby also had a six-month history of panting, polyuria, polydipsia, and recurrent ear infections. Physical examination before the dental procedure revealed a swelling in Libby's perineal region, and the veterinarian subsequently diagnosed a left perineal hernia. The dental prophylaxis was rescheduled for a later date, and Libby was referred to the Mississippi State University College of Veterinary Medicine (MSU-CVM) for hernia repair.

Referral evaluation

On presentation to MSU-CVM, Libby was bright and alert. The left perineal hernia was noticeable and was easily reduced. Her abdomen appeared distended, but abdominal palpation revealed no abnormalities. The results of a serum chemistry profile revealed mild increases in alanine aminotransferase (136 U/L; reference range = 10 to 90 U/L) and alkaline phosphatase (153 U/L; reference range = 11 to 140 U/L) activities. Libby's urine specific gravity was 1.019. Based on these results and the history of panting, polyuria, polydipsia, and recurrent infections, a workup for hyperadrenocorticism was performed.

Adrenal function test results




Results of an adrenocorticotropic hormone (ACTH) stimulation test revealed a baseline cortisol concentration of 8.5 μg/dl (reference range = 1.4 to 5 μg/dl) and a one-hour post-ACTH cortisol concentration of 24.8 μg/dl (reference range = 5.5 to 20 μg/dl). These results confirmed hyperadrenocorticism.

Imaging

Abdominal imaging was performed to differentiate pituitary-dependent hyperadrenocorticism (PDH) from an adrenal tumor. The abdominal radiographic findings were unremarkable. Abdominal ultrasonography revealed normal-sized and symmetrical adrenal glands and no evidence of an adrenal mass. Also noted were a single hepatic lesion and a single splenic lesion, as well as a gallbladder mucocele in the early stages of development. Ultrasound-guided fine-needle aspirates of the lesions within the liver and spleen were obtained. A thoracic radiographic examination was also performed, and the findings were unremarkable.

Diagnosis

Libby's abnormal ACTH stimulation test results along with the abdominal ultrasonographic findings provided a working diagnosis of PDH.

Cytologic examination of the hepatic and splenic lesion aspirates showed mild extramedullary hematopoiesis, likely consistent with regenerative nodules. The liver aspirates also showed evidence of vacuolar degeneration, a finding consistent with hyperadrenocorticism.

*The dog in the photograph is not Libby, the dog described in this article.