Effects of Pasture and Obesity on ID and Adiponectin in Horses  

Insulin dysregulation (ID) and hypoadiponectinemia are risk factors for laminitis. These conditions are sometimes, but not always, associated with obesity. A longitudinal study aimed to investigate the effects of pasture consumption and obesity on ID and circulating total adiponectin in ponies. 

Study Population

Seven native-breed ponies with normal basal and post-oral sugar test (OST) responses and body condition scores (BCS) of 4.3-5.5/9 were allowed to graze until they reached BCS 7/9. Ponies were then maintained at BCS 7/9 until completion of the study (Week 22). The researchers determined morphometric measures; OST; insulin tolerance test (ITT); plasma adiponectin; whole-blood expression of receptors for adiponectin, insulin, and insulin-like growth factor 1; and pasture conditions (height and vigor, using a simple pasture scoring system for potential use by horse owners) fortnightly.  

Study Findings

Median (range) BCS increased significantly (p < 0.001) from 5.0 (4.3-5.5; Week 0) to 7.2 (5.7-7.5; Week 22). Basal insulin did not change significantly over the study, but median post-OST insulin was significantly higher (p < 0.05) at Week 14 (95.2 [17.9-114.0] μIU/mL), Week 16 (103.0 [16.4-166.0] μIU/mL), and Week 20 (93.6 [10.0-153.0] μIU/mL) than Week 0 (25.0 [10.0-64.0] μIU/mL). Compared with Week 0, ITT results were significantly lower at Weeks 2-6 and 12-20, and adiponectin was significantly lower at Weeks 10-22 (p < 0.05). Adiponectin decreased in all ponies during the study. Both low (3/10) and high (8-9/10) pasture scores were significantly associated with low ITT results. Low pasture scores were associated with low adiponectin. BCS was significantly associated with basal insulin, post-OST insulin, and ITT results but not adiponectin. 

Bottom Line  

Six ponies developed hypoadiponectinemia, all ponies developed ID at some point during the study, and ID status varied throughout, sometimes changing from week to week, although these changes were not consistent across ponies. Both short, stressed grass and long, lush grass were associated with decreased tissue insulin sensitivity. 

https://beva.onlinelibrary.wiley.com/doi/10.1111/evj.14507

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• Use of Oat Straw to Manage Equine Obesity
• How to Feed Horses Prone to Endocrinopathic Laminitis
• Groundbreaking Equine Endocrine Research

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