Diabetes Mellitus remission in three acromegalic cats after cabergoline treatment

VIDAL PN; PIGNATARO OP; CASTILLO VA; MICELI DD

Bologna

Jornada; Summer School of Veterinary Endocrinology 2018; 2018

European Society of Veterinary Endocrinology (ESVE)

INTRODUCTIONAcromegaly or hypersomatotropism is a chronic metabolic disease caused by hypersecretion of growth hormone. In cats, it is mainly caused by a functional adenoma of pituitary gland (somatotropinoma). This syndrome is characterized by insulin-resistance diabetes mellitus (DM) and progressive overgrowth of soft tissues, bones and viscera. It is estimated that 17-32% of diabetic cats are acromegalic. The objective of the treatment is twofold: to control the hypersomatotropism itself and to control the concurrent diabetes mellitus. In this case report, we describe 3 acromegalic cats that achieved diabetic remission after treatment with cabergoline.CASES DESCRIPTIONThree diabetic cats (domestic short-haired, neutered males, case 1: 15 years old, case 2: 7 years old, case 3: 13 years old) were referred with polyuria, polydipsia, polyphagia and poor glycemic control, despite receiving elevated doses of insulin (glargine: 8, 10 and 7 U/cat bid) and commercial diet of diabetic cats. None of them had been treated with glucocorticoids or progestagens.- CLINICAL, LABORATORY AND IMAGING FINDINGThe clinical findings were mild prognathia inferior and overweight in case 1, overweight in case 2, and mild broad facial features and mild widening of interdental spaces in case 3. In cases 1 and 2, hyperproteinemia were observed. Hyperthyroidism, Cushing's syndrome, infectious diseases and any other systemic disorder capable of inducing insulin resistance were ruled out. Biochemical diagnosis of acromegaly was established by high IGF-1 levels obtained in the three cats (>1500, 1200, 947 ng/mL). In case 3, magnetic resonance imaging revealed increased pituitary size (5.7 mm width x 4.5 mm height).- TREATMENT An oral dose of 10 μg/Kg cabergoline (Dostinex) every 48 h was prescribed. At home, the owners controlled clinical signs and adjusted the insulin dose (twice daily) according to glycemia (measured with glucometer) observed before each insulin administration and according to our medical indications. In the first week there were no significant changes in glycemia, but as the weeks were passing by, the insulin requirements were progressively reduced (evidenced by the daily monitoring, weekly glucose curves and fructosamine). Between the second and third month of cabergoline-treatment, insulin administration was no longer necessary in any cat. In this way, DM remission was achieved in these three acromegalic cats, and at least so far, there has been no recurrence in DM (case 1: 18 months, case 2: 9 months, case 3: 24 months). IGF-1 levels were reduced with cabergoline only in case 3. No side effects were observed in the study. DISCUSSIONThere is still a lack of studies with a greater number of animals and a longer follow-up over time to evaluate the use of cabergoline in acromegaly. Radiotherapy and hypophysectomy are expensive (such as pasireotide) and that they require specialized centers. Therefore, cabergoline could be an effective and economical option to treat acromegalic cats (as it is in human medicine), at least to reduce insulin resistance and, in some cases, to achieve diabetic remission.