Last Updated on February 25, 2022 by Allison Price
Two top researchers discuss insulin’s effects on the body, and how to manage the IR horse
If you have ever wondered “Wait, which one is worse–insulin sensitivity in horses or insulin resistance? We don’t want our horses to have too much insulin. It can be confusing to hear about insulin resistance and insulin sensitivity. It only adds to stress when dealing with horses who might have insulin-related problems.
It is crucial to understand insulin and how it works in order to manage insulin-related issues in horses. The second step? The second?
Insulin: How it Works or Doesn’t Work
Glucose is a sugar that we get from our food. It supplies energy to all of our cells, including the muscles, skin, and brain. It needs to be transported from the digestive system to the bloodstream, and then into all the cells and tissues of the body.
This is where insulin comes in. The pancreas releases insulin when we ingest glucose. It makes sure that the glucose goes where it needs to. The body and its cells cannot survive without insulin. Insulin is a vital part of life so it’s good to have.
However, problems can arise when the body’s signaling system for how much insulin to produce from the pancreas goes haywire, according to Andrew van Eps (BVSc), PhD, MACVSc and Dipl. ACVIM is an associate professor of equine musculoskeletal and research at the University of Pennsylvania’s School of Veterinary Medicine in Kennett square. It is not possible to have too many good things.
Horses and people are not all born this way. They produce more insulin than they require. Van Eps states that some Warmbloods, Arabians and Morgans, ponies, as well as horses, might be at risk of insulin overproduction.
He says that some people produce more insulin when they are hungry, and this is often associated with obesity. As insulin resistance decreases, the body needs more insulin to handle the incoming glucose. It keeps asking for more insulin in an ever-increasing cycle of production increases. Van Eps states, “That’s true insulin resistant (IR).” “The body makes more insulin to make up for the insulin not working well.”
Scientists refer to insulin resistance and insulin sensitivity as insulin dysregulation (ID). Nicholas Frank, DVM. PhD, Dipl., states that it is important to understand ID horses in one group. However, it’s equally important to distinguish between them. ACVIM. Frank is an associate dean in academic affairs at Tufts University and a professor of large-animal internal medicine at Tufts University’s Cummings School of Veterinary Medicine in North Grafton (Massachusetts).
He says, “You cannot assume that you know why these insulin concentrations are high.” “While insulin levels are high in many horses, it is possible that some horses have some IR. But that may not be all.
IR is a common condition in horses with high insulin levels. However, this may not be all that the horse has.Dr. Nicholas Frank
Horses and Humans
Although we hear of insulin-dependent patients in humans, our veterinarians seem to always be working to lower the insulin levels in horses. Is it possible to either add or remove insulin?
It seems that the answer is species-related. According to our sources, equids react differently to IR than humans.
Van Eps states that IR humans produce more insulin than IR horses in response to this insensitivity. “But, in humans, the insulin production slows down and the pancreas stops producing enough insulin to keep up with the demand. This is Type 2 diabetes. Type 1 or “juvenile”, diabetes is when the pancreas stops producing insulin due to an autoimmune process that destroys cells.
Our sources confirm that diabetes can occur in horses but it is rare. Frank says that horses seem to have greater ability to continue secreting insulin. Frank explains that insulin is secreted by the human pancreas, which also produces a protein that can damage the pancreas. This doesn’t appear to happen in horses. Horses can continue to produce insulin for many years.
The Woes Of Excess Insulin
Horse owners know that excessive sugar intake can cause laminitis. Let’s take a look at why.
Insulin triggers a process that causes cells to take in glucose. This is biochemically a reaction that activates a protein called a receptor. Insulin activates the insulin receptor, and when that happens everything is fine.
Unfortunately, however, there’s a very similar receptor with a very different job–growth–appropriately called the insulinlike growth factor (IGF) receptor. It is not known exactly what happens when insulin “accidentally”. Scientists have made a reasonable guess. Van Eps states that “the latest evidence suggests the lamellar cells in the hoof (also called lamellae), get pushed into growth cycles, disrupting their normal attachment to one another.”
Laminitis is the most severe side effect of ID.
Other effects are not clear. Van Eps states that insulin anomalies do not seem to lead to changes in attitude and activity levels. However, excess insulin can cause damage to other tissues and organs in humans (e.g. the kidneys).
The obesity associated with IR comes with its own risks. Frank explains that fat tumors, pedunculated lipsomas (benign lipomas) can form around the intestines. They can cause damage to the bones and joints and even reproductive issues.
Above All Else, Diet
How do you manage your ID horse? “Diet, diet, diet,” says van Eps.
According to him, the best way to keep your ID horses healthy is to reduce sugar intake and add protein if necessary. While testing, medication, and exercise are all great and helpful, nothing can replace a low-sugar and protein-stable diet for these horses.
Our sources agree that this means that these horses should be kept off green pastures and avoid supplemental concentrates. Our sources agree that owners of horses with severe endocrine disorders should have their hay tested to determine the ethanol soluble carbohydrate and starch levels. These should not exceed 10% of their horse’s daily ration. TheHorse.com/151021 has more information about nutrition recommendations for ID horses.
Breaking the Sweat
An ID horse with a medical condition should not be assumed to have special work requirements. His health condition is not going to impact his performance or athletic ability (except if he has Laminitis). He needs to be active. Frank states that high levels of exercise are beneficial for keeping insulin levels down.
Many owners find this a problem. Frank states that horse owners are becoming more busy and don’t have the time or energy to exercise their horses often. They’re basically companion animals. We recommend that ID horses be exercised every day or every other days to produce significant work. This could include trotting, cantering and so on. He should be working out.
Medications as Needed
For the most part, a good diet and exercise plan will be sufficient for the ID horse. However, some horses may be very affected. You can see this on insulin response tests. These horses may need medication to manage their condition.
Frank states that severely ID horses can be difficult to manage because they tend to have high insulin levels despite being managed well.
Synthetic thyroid hormone, synthetic thyroxine, can increase metabolism and help to reduce fat deposits. Van Eps says that metformin, an anti-diabetes medication, can “blunt insulin response to sugar in the diet.” Van Eps says that metformin appears to have a local effect on the gut to decrease the absorption sugar. This may prove to be especially helpful for horses with too high insulin levels.
These drugs can only be prescribed by a veterinarian.
Anti-Surprise Screening
Regular evaluation is an important part of managing an ID pony. Regular evaluation is an important part of managing an ID horse. You need to keep an eye on his health and make sure that he doesn’t gain or lose too much weight. Also, don’t forget about what you can’t always see.
Periodic oral sugar/glucose testing is a good way to see how insulin reactions have changed over time. Van Eps states that insulin concentrations can be affected by age and body condition. Therefore, a yearly test is recommended for a case where the horse has been previously diagnosed.
Frank adds that with age comes an increase in the risk of diseases like pituitary intermedia dysfunction (PPID or Equine Cushing’s Disease). This is especially true for horses already diagnosed with ID. A veterinarian can evaluate your horse and detect early signs of PPID to give you a head start in managing it.
Finally, don’t forget hoof radiographs (X rays), says van Eps. Van Eps says that the laminitis seen in these horses can sometimes be very insidious and the horse may not be necessarily lame. Sometimes people are shocked by how advanced laminitis can be on radiograph. Therefore, it is important to have an evaluation once or twice per year in an established (ID). This will help avoid any nasty surprises.
These horses may have laminitis, which can be very insidious.Dr. Andrew van Eps
Staying healthy
The ID-affected horse doesn’t have any physical problems. Frank says that he is more vulnerable to laminitis when his health condition is complicated. He says, “It doesn’t take much to get the severely affected horses back into laminitis.”
There are several diseases that can increase your risk of developing laminitis: infections, fevers and intestinal diseases. He says that if a horse already has a high insulin level, these events could make them more dangerous. “So, good medical care is even greater.”
Genetics and New Therapies
Researchers are focusing on the genetic components of Equine ID. The goal is to identify the genes that are associated with the condition and how we can manage them. Van Eps states that it is possible to breed the syndrome from certain lines of horses. This would be “the Holy Grail”.
Frank says that other teams are also studying how the intestinal cells signal the pancreas for insulin production. He adds that he’s “optimistic” about these research. “The question is: could we block these hormones so that they don’t stimulate insulin release?” Current research is underway on new drugs that could help.
Van Eps’ research group collaborates with other researchers to conduct clinical trials of drugs that could interrupt the effects of insulin on the feet. He says that he expects to see meds that stop the negative effects of insulin on the lamellae in the next few years.
Take-Home Message
Insulin-dysregulated horses may live happy, healthy, active, and perform at top levels like all other horses. It is important to ensure that their condition is managed in accordance with current scientific recommendations. Owners of ID horses and ID-prone horses must be able to understand what insulin does and how it can cause problems. These tools will enable them to give their horses the best chance of optimum health, and welfare.
