Equine Cushing’s Syndrome: Long-term effect of Pergolide therapy
Equines Cushing Syndrom – Wirkungen einer Langzeittherapie mit Pergolid
Pongratz M C, Graubner C, Wehrli Eser M
Pergolide is the drug of choice for treatment of equine Cushing’s syndrome (ECS). There are only few detailed studies describing the longterm effects of pergolide treatment in ECS patients. The goal of this study was to evaluate the long-term effects of a pergolide therapy in ECS patients in Switzerland by means of owners’ survey using a questionnaire. Thirty-eight horses diagnosed with ECS between 1999 and 2009 at the Vetsuisse Faculties Zurich and Bern, respectively, and treated for at least 1 month with pergolide (Permax®, Lilly SA, Genf) were included in the study. Diagnosis of ECS was based on history and clinical signs; in 37 horses it was confirmed with a dexamethasone suppression test (DST) and/or measurement of plasma ACTH concentration. The clinical signs before treatment were characterised and the effect of therapy was determined by interrogating the horse owners using a questionnaire. Statistical analysis of the data was performed using a McNemar’s test. The examined horses were 22 (13-36) years old [mean (min-max)]. The population contained 22 warmblood horses, 11 cobs und 5 ponies, including 14 mares, 23 geldings und 1 stallion. Clinical signs were hirsutism (33/9) [(number of affected horses before treatment; number after treatment)], hyperhidrosis (24/7), poor performance (21/3), lethargy (22/3), polyuria/polydipsia (15/5), muscle wasting (19/11), weight loss (13/4), laminitis (15/ 3), ataxia (11/3), skin infections (10/4), bronchitis (4/2) and conjunctivitis (6/2). The dosage of pergolide was 1-2 μg/kg p.o. SID and the duration of treatment was 13.8 (1-38) months. According to the owners, horses responded to treatment within 2 to 4 weeks after initiation of therapy. Thirty-four of the 38 owners (79%) were satisfied with the treatment. Adverse effects were rarely observed (n=11) and if so, they were transient and mild (anorexia, lethargy, diarrhoea). At the time of the study, 10 horses had died or were euthanized (recurrent laminitis, colic, bone fracture, loss of use). The length of survival of these horses after start of treatment was 7.9 (1-22) months. The results indicate an improvement of the clinical signs after pergolide therapy in most of the patients when judged by the owners. At the dosage used here, adverse effects are rare and mostly clinically irrelevant. In conclusion, the administration of pergolide in ECS patients can be supported on the basis of the results in this study.