Hypersomatotropism without concurrent diabetes mellitus in cats: 28 cases (2014-2024)

Hypersomatotropism (HST) in cats has predominantly been associated with diabetes mellitus (DM) and HST in nondiabetic cats is poorly described.

To describe the clinical presentation, clinicopathologic findings, and outcome of nondiabetic cats with presumed HST.

Twenty-eight client-owned cats.

Multi-site retrospective study based on medical records of nondiabetic cats seen at 10 institutions between 2014 and 2024 with presumed HST (elevated serum insulin-like growth factor-1 [IGF-1] ± clinical signs compatible with acromegaly ± documented pituitary enlargement). Clinical presentation, diagnostic findings, and survival times were reviewed.

Twenty-eight cats with HST were included. Twenty-six cats were males, and 2 cats were females; mean age was 9.5 years (±SD 3.5 years); mean body weight was 7.1 kg (±SD 2.1 kg). The median serum IGF-1 concentration was 1236 ng/mL (range 704-2455 ng/mL). Nineteen of 28 cats (68%) had clinical signs possibly related to acromegaly: prognathia inferior (13/28), weight gain (12/28), broad facial features (10/28), abdominal enlargement (10/28), respiratory stridor (9/28), polyphagia (9/28), and signs of neurological disease (3/28). The most common clinicopathological abnormalities were hyperproteinemia (12/28), serum creatinine above the reference interval (RI) (10/28), and urinary specific gravity below the RI (9/28). Hypertrophic cardiomyopathy phenotype was identified in 8/17 cases. The most common comorbidity was chronic kidney disease (10/28). The median survival time after diagnosis was 24 months (range 1-103 months).

Hypersomatotropism can present without DM and should be considered in cats with signs suggestive of growth hormone excess or a pituitary tumor.