Recovery from Laminitis: The Road May Be Longer for Some Horses

How long will the road to recovery be for lamanitic horses? New data show that horses typically fall into one of two categories: those that improve quickly or those that are slower to recover and prone to relapse.^* Younger horses and those with higher blood glucose and insulin levels tend to fall into the second group.

These findings are intriguing because, until now, most relevant research has focused on factors that contribute to the development of laminitis. This is a rare prognosticative study. In other words, we know that horses with insulin dysregulation and hyperinsulinemia (elevated circulating insulin levels) are at risk of laminitis if they consume meals high in nonstructural carbohydrates. If these horses do founder, what are their chances of survival and how long will it take to recover?

To answer this important question, researchers recruited 37 horses with naturally occurring hyperinsulinemia-associated laminitis (HAL). Demographic, morphologic, hormonal, and metabolic data were collected from all horses to discover factors associated with the rate of improvement from HAL. Severity of lameness was also evaluated on days 0, 4, 9, 14, 25, and 42 after diagnosis.

“During the first nine days of the study after the diagnosis of HAL, horses were managed according to ‘best clinical practice.’ This included strict stall rest or confinement and diet restriction to include only hay. Horses were also offered specialized shoeing in the form of supportive pads,” described Catherine Whitehouse, M.S., a Kentucky Equine Research nutrition advisor.

Based on the lameness and laminitis scores recorded on evaluation days, horses were found to either respond rapidly to treatment, within 14 days of diagnosis, or more slowly. Most horses—27 of the 37 or 73%—fell into the fast group, whereas the remaining 10 horses still had signs of lameness and laminitis at day 14 or suffered a relapse after that time.

After analyzing the demographic, morphologic, hormonal, and metabolic data, horses in the slow group were significantly younger (mean age was 12.5 years in the slow group versus 17 years in the fast group). In addition, while blood glucose and insulin levels remained normal for all horses, horses that improved more slowly had significantly increased glucose and insulin after diagnosing HAL until day 25 compared to the fast group.

Some of the many factors that did not contribute to lack of improvement from HAL included body fat or body condition score; previous episode of laminitis; elevated concentrations of ACTH, a hormone typically raised in horses with pituitary pars intermedia dysfunction (PPID, Cushing’s); and treatment for PPID with pergolide.

“Prior to laminitis, almost all horses were fed hay and the majority, 28 of the 37 horses, were also fed other feedstuffs, including pasture, grains, and concentrates. During the first nine days of study after diagnosing HAL, all horses were offered hay only. After those initial nine days, other feed types were allowed to be offered to the fast-recovery group; however, 90% of the horses in the slow-recovery group remained on hay-only diets from days 10 to 14,” Whitehouse explained.

Therefore, diet did not appear to have contributed to the rate of recovery, though hay quality was not evaluated in this study. Horses included in the study were client-owned with naturally occurring disease and therefore resided on 16 different properties. The nonstructural carbohydrate content of the forage offered to the laminitis horses was not evaluated at any point during the study.

According to Whitehouse, “Dietary management of insulin dysregulation should focus on reducing total nonstructural carbohydrate intake.”

She therefore recommends the following management strategies for horses with insulin dysregulation:

• Access to grazing should be carefully managed and prohibited in some cases;
• Forages should have a nonstructural carbohydrate content of less than 12% on a dry matter basis. Some horses require further restrictions based on the severity of insulin dysregulation;
• Small, frequent hay meals are a key feeding practice to help minimize fluctuations in blood glucose and insulin after feeding; and
• Supplement with a low-calorie, low-intake vitamin and mineral supplement.

 ^*Sillence, M., A. Meier, M. de Laat, R. Klee, and D. Reiche. 2022. Demographic, morphologic, hormonal and metabolic factors associated with the rate of improvement from equine hyperinsulinaemia-associated laminitis. BMC Veterinary Research 18(1):49.