Feline hypersomatotropism without concurrent diabetes mellitus: 21 cases (2014-2023)

MICELI DD; STIJN J.M. NIESSEN, JUAN P. REY AMUNATEGUI, FEDERICO FRACASSI, GUSTAVO POMPILI, FLAVIA TAVARES, ESTELA MOLINA, RODOLFO LEAL, FLORIAN ZEUGSWETTER, DOROTEIA BOTA, ANDREA CORSINI

Barcelona

Congreso; ECVIM CONGRESS; 2023

Feline hypersomatotropism (HST) has previously been predominantly characterized by the presence of diabetes mellitus (DM). While in humans most cases do not develop overt DM, in cats only 5 non-diabetic HST cases have been published to date. This multicentric retrospective case series aims to describe the clinical findings and outcome of non-diabetic cats with HST. Medical records of non-diabetic cats with HST admitted between March 2014 and February 2023 to 8 Veterinary Hospitals were evaluated. The diagnosis of HST was based on compatible clinical signs and increased serum insulin-like growth factor 1 (IGF-1) concentration (>900 ng/mL). Twenty-one cats with clinical signs compatible with growth hormone excess and an increased IGF-1 concentration were included. Eighteen cats were Domestic Short-Hair, 2 Domestic Long-Hair, and 1 Norwegian forest. Twenty cats were male (of these 19 neutered) and one cat was a spayed female; median age was 10 years (range 2-15 years); median body weight was 7.3 Kg (range 4.2-12 Kg). Pituitary enlargement was detected in 9/12 (75%) cats on computed tomography imaging. Sixteen out of 21 (76%) cats had phenotypic changes consistent with acromegaly: prognathia inferior (10/21), broad facial features (8/21), abdominal enlargement (8/21). Additionally, 10/21 cats showed weight gain, 6/21 polyphagia, 6/21 respiratory stridor, 2/21 degenerative arthropathy and 1/21 neurological signs. The main reasons for considering HST were acromegalic phenotype and weight gain. The most relevant clinicopathological abnormalities were: hyperproteinemia (8/21), azotemia (7/21), increased liver enzymes (5/21), decreased urinary specific gravity (5/21), anemia (4/21), hypertriglyceridemia (2/21), and hypercholesterolemia (2/21). Hypertrophic cardiomyopathy phenotype was identified in 8/16 cases. The most common concurrent diseases were chronic kidney disease (7/21) and neoplasia (7/21). Systolic hypertension was reported in 7/10 cases. Seven cats received treatment with cabergoline, one cat underwent hypophysectomy and one cat radiotherapy. Cabergoline normalized IGF-1 concentrations in 3/7 cases. One cat developed DM after corticosteroid administration post-radiotherapy. Most non-diabetic HST cases (76%) were diagnosed on the basis of observed phenotypic changes consistent with growth hormone excess. Cabergoline was not consistently effective to control IGF-1 excess, though allowed normalization of IGF-1 concentration in 3 cases. This study suggests that HST should also be considered in cats without DM. A focus on screening a wider range of presentation types could lead to the uncovering of a larger non-diabetic HST population among cats.