Equine Grain-Associated Disorders

There is growing research to suggest that insulin resistance, as a result of long-term consumption of grains, sweet feeds and even lush pasture may be responsible for many of the common conditions we continue to deal with in horse management. Often these horses are referred to as having Equine Metabolic Sydrome or Metabolic Disease.

Insulin resistance has been generally defined as a state in which normal concentrations of insulin fail to elicit a normal physiological response (Kahn, 1978). 

Insulin resistance in horses has been associated with:

• Obesity and laminitis (Jeffcott et al., 1986; Pass et al., 1998; Sillence et al., 2007),
• Osteochondritis dissecans (Pagan et al., 2001),
• Exertional rhapdomyolysis or tying up (Valentine et al., 2001)
• Pituitary adenoma (Cushing’s Syndrome, Garcia and Beech, 1986) and even may play a role in
• Colic (Hudson et al., 2001). 

Researchers have found that obese horses are more likely to be insulin resistant (Hoffmann et al., 2003).  The authors found that insulin sensitivity was approximately 80% lower in obese horses than in nonobese horses, which is similar to that reported in humans (Lee et al., 1992). 

Dietetics

It has been recommended that rations designed for horses with grain associated disorders should avoid high glycaemic feeds (Kronfeld, 2001; Garcia and Beech, 1986; Johnson, 2002; Kronfeld and Harris, 2003). 

Feeds to be avoided are feeds containing an abundance of soluble carbohydrates that are hydrolyzed in the small intestine to form glucose (Kronfeld, 2003). Likewise dangerous are certain sugars, such as fructosan which are abundant in rapidly growing pasture. 

Ø      Energy intake especially in the form of starch and sugar from grain and molasses should not be excessive

Ø      Young rapidly growing pasture which is rich in sugars may need to be limited

ü      Fats and oils may be of use in lowering the glycaemic response to a feed, however as there is minimal nutritive value from oils, mineral and vitamin supplementation may also be required

ü      High fat, and fat and fibre feeds if properly formulated may be of use

Equine Consulting Services has had success working with owners and trainers, reformulating rations of horses with laminitis, and thoroughbreds prone to tying-up. In addition, we are involved with a major Rural Industries Research and Development Corporation (RIRDC) funded project designed to examine the effect of insulin resistance on skeletal disease in growing foals.  For further information, please contact us at: info@equineconsultingservices.com.au

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