On a personal note, this subject is particularly important to me because I have been fortunate to have had many opportunities to care for insulin resistant horses on nutritional research trials in the past few years.
To find our research subjects, we would look through the university’s records to see which ones had a history of laminitis or drive across the acres of farmland on the lookout for those typical characteristics that indicate a horse might have metabolic disease (i.e. higher body condition score).
Ok, so maybe we went shopping for the cresty-necked farm fatties, but it was awesome because these horses were always so happy to see people. They assumed you *might* be the food lady that day, and, well, they love to eat.
I can empathize with the pain of all horse owners who could check for digital pulses in their sleep and are constantly watching for any signs of lameness or pain. I, too, have felt the dread that creeps in when you see that your horse has slipped off his grazing muzzle while turned out to pasture.
Ok, maybe I got ahead of myself. Let’s start from the beginning.
What is insulin and why is it important?
Insulin is a peptide hormone that is released from the pancreas and regulates the metabolism of carbohydrates, fats and proteins.
Its primary purpose is to promote the uptake of glucose from the blood into the target tissues, such as fat, liver or skeletal muscle cells in response to high levels of blood glucose . Maintaining appropriate blood glucose levels is vital for health because the wrong amount (too much or too little) of glucose can have devastating health consequences and can even be life threatening.
What is insulin resistance?
Insulin resistance (IR) is a condition where the body tissues become less sensitive to the stimulation of insulin.
Ultimately, this leads to more and more insulin secretion from the pancreas in an attempt to force the glucose into tissues.
Because insulin is an anabolic hormone, IR also affects the signaling mechanisms between cells in many tissues, leading to all kinds of different metabolic abnormalities involving not only carbohydrates, but also fat and protein.
We now know that insulin metabolism can be affected at many different steps, including reduced clearance once it is in circulation (i.e. high levels of insulin in the blood), abnormal pancreatic metabolism, perturbed gut signaling pathways and more.
What are the causes of insulin resistance?
- Systemic inflammation
- Pituitary Pars Intermedia dysfunction (PPID) or Cushing’s Disease
- Physiological responses to stress
- Nutrition (prolonged intake of high NSC diets, or pasture with lots of sugar and starch)
What are the signs of insulin resistance in horses?
- Above average body condition score
- Cresty neck
- Visible excess fat tissue
- Ability of the horse’s back to hold water
- High blood insulin levels at rest and following a carb-heavy meal
- Incidences of laminitis or founder
What are the common screening tests used?
- Oral sugar test
- Combined glucose insulin tolerance test
- Insulin tolerance test
- Thyrotropin-releasing hormone stimulation test (for PPID/Cushings)
Treatment for insulin resistance
The most important treatment for IR is managing the horse’s diet. In many cases, following a low carb (NSC) diet is the ticket to success! Be sure to have your hay tested and work with an equine nutritionist to choose a low carb grain product that meets your horse’s nutrient requirements without all the added starch and sugar. In addition, choosing low carb and low sugar horse treats such as peanuts, celery, hay cubes and beet pulp cubes are ideal.
Exercise is another crucial component of health for these horses. Gradually increase the amount of exercise for your insulin resistant horse as these animals can be particularly sensitive to change. Work with your veterinarian closely while managing these horses and keep a detailed record of any changes in your horse and your nutrition/exercise program.
Supplements for insulin resistant horses
Because the pancreas, the organ that releases insulin, is part of the horse digestive tract, overall gut health for these horses is critical for recovery and prevention of further problems.
For this reason, horse supplements that support increased digestive and immune function can be highly beneficial.
While insulin resistance can seem daunting, the good news is that nutritional management is both achievable and effective. Work with your veterinarian and equine nutritionist to put together a plan for these horses; It will be well worth your time and effort and your horse’s quality of life will improve drastically.