Abstract
OBJECTIVES: Acromegaly is increasingly recognized as a cause of insulin resistance in cats with diabetes mellitus (DM). The objective of this study was to determine if ultrasonographic changes in selected abdominal organs of acromegalic cats could be used to raise the index of suspicion for this condition. METHODS: In this retrospective case-control study, medical records of cats presenting to North Carolina State University or Colorado State University from January 2002 to October 2012 were reviewed. Cats were included in the acromegaly group if they had insulin-resistant DM with increased serum insulin-like growth factor (IGF-1) concentrations and had an abdominal ultrasound examination performed with report available. A control group included age-matched cats that had abdominal ultrasound examination performed for investigation of disease unlikely to involve the kidneys, adrenal glands, pancreas or liver. RESULTS: Twenty-four cats were included in each group. IGF-1 concentrations in the acromegaly group ranged from >148 to 638 nmol/l. When compared with age-matched controls, cats with acromegaly demonstrated significantly increased median left and right kidney length, significantly increased median left and right adrenal gland thickness, and significantly increased median pancreatic thickness. Hepatomegaly and bilateral adrenomegaly were reported in 63% and 53% of acromegalic cats, respectively, and in none of the controls. Pancreatic abnormalities were described in 88% of the acromegalic cats and 8% of the controls. CONCLUSIONS AND RELEVANCE: These findings indicate that compared with non-acromegalic cats, age-matched acromegalic patients have measurably larger kidneys, adrenal glands and pancreas. Diagnostic testing for acromegaly should be considered in poorly regulated diabetic cats exhibiting organomegaly on abdominal ultrasound examination.