Feline acromegaly: More common than we think

In his presentation, “Acromegaly”, Stijn Niessen, DVM, PhD, DECVIM, PGCVetEd, FHEA, MRCVS, discussed what we currently know about this once rare disease. Of note, Niessen points out that recent studies have shown the prevalence of this disorder is higher than what we thought even a decade ago. Recent reports suggest a prevalence of 26% to 32% among cats.1,2

The diagnosis of acromegaly is based on documentation of elevated insulin-like growth factor (IGF) concentrations, with studies suggesting that a concentration > 1,000 ng/ml is supportive of a diagnosis.1 Niessen stated that there is a risk of false positive and false negative results with this test, but this cut-off appears to provide the greatest sensitivity for diagnosis. Because insulin is required for the production of IGF, false negative results are possible in newly diagnosed diabetic cats. Alternatively, elevated IGF concentrations have been documented in nonacromegalic diabetic cats. 

Niessen went on to explain that acromegaly  may not be on the radar of clinicians caring for diabetic cats because not all cats have the classic phenotypic presentation of acromegaly. While insulin resistance and excessive body weight would be expected in these cases, cats of varying weights and insulin requirements are possible. He noted that any diabetic cat that gains weight even while its diabetes is unregulated would have to be considered as a candidate for this disease.

Therapy for this disorder has also evolved, Niessen said, with hypophysectomy now considered the gold standard if there is not contraindication to the procedure (e.g. comorbidities such as significant renal or cardiac disease, excessive tumor size). Radiotherapy is still an alternative, though results are less predictable. Medical management of this disease with long-acting somatostatin analogues such as pasireotide is promising, but further studies are still needed.

References

1. Niessen SJ, Petrie G, Gaudiano F, et al. Feline acromegaly: an underdiagnosed endocrinopathy? J Vet Intern Med 2007;21(5):899-905.

2. Niessen SJ. Feline acromegaly: an essential differential diagnosis for the difficult diabetic. J Feline Med Surg 2010;12(1):15-23.