Effects of body weight reduction on insulin-sensitivity in obese ponies

Effekte einer Körpergewichtsreduktion auf die Insulinsensitivität bei adipösen Ponys

Ungru J, Schmengler U, Boston R, Coenen M, Vervuert I

DOI: 10.21836/PEM20130306
Year: 2013
Volume: 29
Issue: 3
Pages: 327-334

The „Equine metabolic syndrome“ (EMS) is a cluster of metabolic abnormalities – characterized by insulin-resistance, obesity and laminitis-, which is especially recognized in ponies. These ponies are called easy keepers; a genotype that is predisposed to develop obesity. As obesity has a strong relation to insulin-resistance, body weight reduction is in the focus of an adequate management in obese animals. In this context, it is of interest in which way insulin-sensitivity changes after a body weight reduction. Therefore, the aim of the study was to monitor insulin sensitivity during a body weight reduction program in ponies. 15 obese ponies (body condition score 8±2 (scale 1-9); cresty neck score 4±1 (scale 0-5) were included in a 14 weeks lasting body weight reduction program (BWRP). Ponies were fed with hay (1- 12.2 kg hay/100 kg BW), grass meal (0.05 kg/100 kg BW) and a commercial mineral mixture. Calculated energy intake varied around 7–8.4 MJ DE/100 kg BW. At the beginning and at the end of the study insulin sensitivity index (SI) was determined by the frequently sampled intravenous glucose tolerance test (FSIGTT). Serum insulin and plasma glucose were additionally analysed in week 0, 1, 3, 5, 6, 7, 9, 11, 12 and 14 during BWRP. At the beginning of the study seven ponies were categorized as insulin-resistant (SI: 0.29±0.25 L/min/μU×10-4) and eight obese ponies were classified as insulin sensitive (SI: 7.0±7.9 L/min/μU×10-4). Body weight reduction (1.4–2.8% of BW weekly) improved significantly insulin sensitivity in the initially insulin resistant ponies (SI: 8.7±13.8 L/min/μU×10-4), whereas insulin sensitivity did not further improved in the initially insulin sensitive ponies (SI: 7.4±1 3.1 Ll/min/μU×10-4). Serum insulin decreased significantly during BWRP. Plasma glucose varied between 3.8–4.6 mmol/L during BWRP. In conclusion, body weight reduction is an important nutritional measure to improve insulin-resistance. Concerning the diagnosis of insulin-resistance, a single serum insulin value is a conclusive method and helps to monitor the progress in insulin sensitivity in insulin resistant ponies during BWRP.