Summary Reasons for performing study Treatment of equine metabolic syndrome ( EMS ) is essential to improve insulin sensitivity and reduce the risk of laminitis. Calorie restriction and increased exercise are the mainstays of treatment but there is potential for poor owner compliance. Objectives To determine whether significant weight loss accompanied by improvements in measures of insulin sensitivity can be achieved in horses and ponies with EMS managed by their owners in their normal environment under veterinary guidance. Study design Retrospective clinical case series. Methods Horses and ponies attending 2 university hospitals for investigation and treatment of suspected EMS were eligible for inclusion in the study. Animals underwent a clinical examination, basal and dynamic endocrine testing; those with pituitary pars intermedia dysfunction (PPID) were excluded. Owners were given individually tailored diet and exercise programmes to follow for between 3 and 6 months. After the treatment period, clinical examination and endocrine tests were repeated and results compared to the initial assessment. Results Nineteen animals were recruited to the study, 17 with a history of laminitis. All animals showed a reduction in body condition score (P<0.001) and 18/19 had a reduction in bodyweight (P<0.001) between assessments. There were significant (P<0.05) reductions in basal insulin, insulin at 45 min during a combined glucose insulin tolerance test ( CGIT ), time for blood glucose concentration to return to baseline during a CGIT and mean area under the glucose curve. Conclusions A diet and exercise programme tailored to the needs of the individual animal and implemented by the owner results in weight loss accompanied by improvements in insulin sensitivity.