Insulin Dysregulation or Equine Metabolic Syndrome

5 Things to know about Insulin Dysregulation as a Horse Owner: 

1. Laminitis can be a common symptom of the problem.

2. Horses and ponies equally present with the condition. 

3. Not a shortage of insulin but a reduced sensitivity to insulin within the body.

4. Management consists of a combination of dietary and exercise management changes.

Equine Metabolic Syndrome (EMS) is most likely seen in horses and ponies that were once thought of as the good doers. There is a dysregulation between the production of insulin and the sensitivity of the cells to the insulin. Insulin is released in response to glucose in the blood stream. The insulin helps all the cells that need to use the glucose activate a receptor that allows the absorption of the insulin. 

Common presenting problems: 

1. Breed specifics: Horses and ponies that were designed to live in harsh conditions: Ponies, Arabs, donkeys. These breeds are not designed to be placed in the common environment that many horses and ponies are kept in. 

2. Excess carbohydrates and lack of roaming to use up energy leads to the build-up of excess fat storage. 

3. Common presenting signs: 

   1. Laminitis 

   2. Excess fat pads, most likely around the neck ribs and tail head. 

   3. Obesity of the horse or pony. Often body condition score greater than 7 out of 9. 

Diagnosis: 

1. Clinical appearance 

2. Blood test results: 

   1. Insulin levels either resting or after fasting and allowed to eat a high carbohydrate or sugar meal and retest the insulin 30 mins later. 

   2. Insulin tolerance test: 

      1. Base line glucose test taken 

      2. Insulin administered 

      3. Glucose retested 30 mins after insulin administration. 

      4. The normal horse should have a greater than 50% reduction in glucose level after administration of the insulin 

   3. Tests for Cushing disease such as resting ACTH or a TRH stimulation of the ACTH should be done. 

Treatment: 

Treatment of this condition is centred around three things, with the first two being the most important: 

1. Dietary management: this requires overall reduction in the calorie intake of the horse or pony to return them to a more normal level. 

   1. Forage: 

      1. Weight loss should be slow and steady. Aim is to feed 1.5% of the body weight of the horse in forage. For a 500kg horse that would be 7.5kg of basic grass hay. Ideally, we should be feeding 1.5kg per 100kg of body weight.  

      2. If there is no change with 1.5% then this can be reduced to 1.25% but only after 30 days. 

   2. Concentrates: 

      1. This should be kept to a minimum and should be feeds that have low digestible energy and carbohydrates and fat. 

      2. Should ensure there is a balanced mineral element to the feet. 

   3. Grass access: 

      1. This should be limited so that we can control the dietary input for the horse. High sugar grass and excess availability can have a negative effect on the management. 

      2. Once weight loss has been achieved then we can allow access at periods when the grass has low sugar levels. 

2. Exercise: 

   1. Exercise is a key component of the weight loss program and needs to be managed carefully. 

   2. If there is active laminitis this needs to be dealt with first before anything else. 

   3. Exercise should be regular and varied to ensure adequate weight loss. 

   4. Addition of a day of lunging beneficial so that these horses can have an extra day of exercise. 

3. Medical Management: 

   1. Some drugs such as Metformin can be administered to help these horses loose weight 

   2. Treatment is for a short 3–4-week period while we stabilise any laminitis before allowing exercise to resume. 

Conclusion: 

In conclusion EMS – Equine Metabolic Syndrome or Insulin Resistance is an increasing problem. Often many of these horses can show laminitic changes at low levels that we do not see them happening.