Hoof Nutrition Intelligence is a twice-a-month web segment that is designed to add to the education of footcare professionals when it comes to effectively feeding the hoof. The goal of this web-exclusive feature is to zero in on specific areas of hoof nutrition and avoid broad-based articles that simply look at the overall equine feeding situation.
Below you will find Part 1 of the latest question and answer installment that you can share with your footcare clients.
Q: Is my insulin resistant horse more susceptible to laminitis during the fall months?
By Juliet M. Getty, PhD
A: Horses are more likely to suffer from laminitis in the fall than at any other time of the year. This is due to high NSC (non-structural carbohydrates) levels resulting from cooler nighttime temperatures and increased blood ACTH (adrenocorticotropic hormone) secretion from the pituitary gland. Both can lead to elevated insulin levels.
Simple sugars (denoted as ethanol soluble carbohydrates, shown as ESC on a hay analysis report, along with starch are digested and end up as glucose. Once glucose enters the bloodstream, it signals the pancreas to produce insulin.
Elevated insulin is the most common cause of laminitis. It stimulates the production of “insulin-like growth factors” within the hoof’s laminae, resulting in proliferation of the epidermal layer. When the epidermal layer lengthens and stretches with uncontrolled growth, it can weaken the laminae. This can lead to a structural failure by compromising the connection of the coffin bone to the hoof wall, creating a gap between the wall and the sole. You may see some hemorrhaging under your horse’s foot, which is an indication of laminitis.
Insulin levels also rise due to the normal hormonal cascade initiated by stress. Intense exercise, mental discomfort, pain, or an empty stomach (there should always be a steady flow of forage through the digestive tract) cause the pituitary gland to release ACTH. This signals the adrenal gland to produce the stress hormones cortisol and epinephrine, both of which are needed to release glucose for energy out of glycogen stores in the liver and muscle.
Any condition that is influenced by elevated insulin, such as metabolic syndrome or equine Cushing’s disease, needs to be managed by feeding a forage with a low level of ESC (simple sugars) plus starch. It is best for this to be less than 11% on a dry matter basis to avoid both endocrine-related and sepsis-related forms of laminitis.
The bottom line is that insulin resistant (IR) horses should be removed from pasture in climates once nighttime temperatures start to get cold in the fall. Furthermore, ACTH levels also go up during the early fall, increasing the risk for laminitis especially in IR and cushingoid horses. Test your hay for suitability and feed it free-choice to avoid stress during those times when pasture must be restricted.
Juliet M. Getty, PhD, is an independent equine nutritionist with a wide U.S. and international following. Located in Lewisville, Texas, her research-based approach optimizes equine health by aligning physiology and instincts with correct feeding and nutrition practices.
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Click here to read part 2 of the Aug. 15, 2020 installment of Hoof Nutrition Intelligence: How long will it take to improve the poor quality hooves on my 3-year-old mare?
Click here to read more installments of Hoof Nutrition Intelligence.