Feline acromegaly without concurrent diabetes mellitus : 9 cases (2018 2022)

MICELI DD; GUSTAVO A POMPILI , JUAN P REY AMUNATEGUI, ANDREA CORSINI, FLAVIA TAVARES

Congreso; Summer School ESVE 2022; 2022

IntroductionAcromegaly, or hypersomatotropism (HST), is a chronic disease caused by hypersecretion of growth hormone (GH). Feline HST is characterized by the presence of diabetes mellitus (DM), and it is estimated that 17.8–24.8% of diabetic cats in Switzerland/ the Netherlands and the UK have an excess of GH. However, not all cats with HST necessarily have concurrent DM. In acromegalic humans, most cases do not develop overt DM. Reports in felines about this issue are lacking and only 5 cases with HST without DM have been published to date. In the present study, 9 cases of feline acromegaly without concurrent DM are described.Cases descriptionCats were recruited from private clinics of Buenos Aires, Argentina (n=7), and Rio de Janeiro, Brazil (n=2), between 2018 and 2022. The diagnosis of acromegaly was made according to clinical signs of GH excess, serum IGF-1 concentration (>1000 ng/ml) and pituitary CT images (n=4). None of the cats met the diagnostic criteria for DM, according to the ALIVE-ESVE criteria.Seven cats were Domestic Short Hair and two cat was Domestic Long Hair. All cats were male (only one cat was not neutered); median age was 10 years (range 2-13 years); median body weight was 7 Kg (range 4.5-10.5 Kg). Intracranial imaging was perfromed in 4/9 cats, all with pituitary enlargement detected by CT. All cases had phenotypic changes consistent with acromegaly at the time of diagnosis: prognathia inferior (7/9), broad facial features (7/9), abdominal enlargement (5/9), clubbed paw appearence (3/9). Additionally, 4/9 showed polyphagia, 4/9 showed weight gain, 3/9 showed respiratory stridor and 1/9 showed degenerative arthropathy. The reasons for referral were: acromegalic features (6/9), weight gain (2/9), hypertension with bilateral adrenomegaly (1/9). The most relevant biochemical or hematological abnormalities were: hyperproteinemia (6/9), mild azotemia (5/9), increases in liver enzymes (3/9), hypertrglyceridemia (2/9), hypercolesterolemia (1/9), anemia (2/9) and decreases in USG (4/9). The most common ultrasonographic abnormalities were bilateral chronic nephropathy (6/9) and bilateral adrenal hyperplasia (3/9) [hepatomegaly (2/9) and thyroid cysts (1/9)]. Left ventricular hypertrophy was identified in 4/9 cases. Systemic arterial hypertension was reported in 5/9 cases. Of the 9 cases, 6 cats received treatment with cabergoline, the other cats did not receive any treatment for excess GH. IGF-1 concentrations did not show significant differences after cabergoline treatment. Cabergoline allows normalization of IGF-1 concentrations in 2/6 cases. The most common concurrent diseases were chronic kidney disease (5/9) and neoplasias (5/9: soft tissue sarcoma [2/5], mastocitoma [1/5], pituitary-dependent hypercortisolism [1/5] and cecal tubular carcinoma [1/5]). None of the cats developed DM. Of the 9 cases, 5 had died for several contributory causes: metastases, end stage of chronic kidney disease, heart failure, pleural effusion, pulmonary edema. Discussion and conclusionsThis is the largest case series to date to describe acromegalic cats without concurrent DM Epidemiological studies concerning this specific population have not been evaluated. All cases had phenotypic changes consistent with acromegaly at the time of diagnosis The most common concurrent diseases were chronic kidney disease and neoplasia. Cabergoline seems not effective to control IGF 1 excess in cats with acromegaly without concurrent DM (only evaluated in 6/9). However, cabergoline allows normalization of IGF 1 concentrations in 2/6 cases. The present case series highlights that acromegaly should not be suspected only in diabetic cats. Further studies should be focused on identifying this condition in non diabetic cats.