Diabetes in Horses – Insulin Dysregulation
Insulin is needed to make glucose enter cells and be used by the body for energy. What happens when the insulin-glucose connection breaks down? Insulin dysregulation and eventual resistance wreaks havoc on the body in many ways.
Insulin dysregulation, resistance, and Equine Metabolic Syndrome
Equine Metabolic Syndrome (EMS) is the scientific name given to the “easy keepers”, horses who are obese, develop abnormal fat deposits on regular diets, and reduced ability to lose weight. Research has now indicated that most of those with EMS also have inappropriate insulin and glucose metabolism, leading to insulin dysregulation or resistance. For this reason, EMS and Insulin resistance can be considered analogous to Type II diabetes in humans.
Clinical signs of IR and EMS
Certain horses, bred to live in harsh climates, seem predisposed to the condition, including ponies, donkeys, Morgan, Arabians, Quarterhorses, and even draft breeds.
The most serious consequence of EMS and insulin dysregulation is laminitis, the separation of the hoof from the coffin bone. Excess insulin in the body has been associated with an inflammatory cascade leading to damage of the laminae of the hoof, and excruciating pain. In these patients, laminitis must be approached by using a team including a veterinarian and a farrier, as well as physiotherapy and a strict nutrition program.
Another consequence of obesity may occur when these horses are sick and do not eat. A normal horse will mobilize their fat stores to be broken down by the liver and used as energy. In horses with EMS, too much fat is released, and overwhelms the liver leading to fat build up in the blood and the horse feels worse. In this vicious cycle, the liver can fill with fat (hepatic lipidosis) and can become damaged leading to liver failure. Emergency veterinary intervention is often needed when signs begin in order to treat and reverse the condition.
How to diagnose IR or insulin dysregulation
Equine Metabolic Syndrome is the physical indicator of abnormal energy use and fat stores. A body condition score (BCS) and description of regional fat deposits is used to describe the patient. However, with proper management, a horse with insulin dysregulation may not appear obese, or have the typical fat deposits, but is still at risk for laminitis or obesity should management change.
An abnormal insulin response can be confirmed by testing baseline insulin and glucose levels. Horses do not need to be fasted, but cannot have received grain or concentrates prior to sample collection, therefore morning sampling is most convenient for most owners. When levels are high, insulin dysregulation or insulin resistance is diagnosed and management plans are developed for the horse.
When a test reveals normal insulin levels but the horse is demonstrating evidence of abnormal fat stores or recurrent laminitis and insulin dysregulation is suspected, then an Oral Sugar Test (OST) is recommended. The horse is fasted, then given a dose of syrup or glucose orally and insulin is measure at 60 and 90 minutes after administration. The amount of sugar given is low, and should not induce an episode of laminitis, but there is a small risk this may occur if the horses is very sensitive to sugar administration.
Because PPID and EMS/Insulin dysregulation can occur concurrently, a baseline ACTH is often collected at the time of diagnosis. PPID decreases a horse’s ability to heal and may worsen the signs of laminitis or hinder a horse’s ability to recover from an acute episode.
How do we manage EMS and Insulin dysregulation?
As with human Type II diabetes, EMS and insulin dysregulation are management primarily through diet and exercise. Your veterinarian can guide you through appropriate diet changes, exercise (if possible), and even recommend supplements to improve weight loss. There is no cure for EMS or insulin dysregulation, therefore long-term, diligent care is needed from the owner with support from the veterinary team.
Diet
Ask the Vet – How to interpret hay analysis – YouTube
Diet changes primarily reduces non-structural carbohydrates (NSC) to below 10%, and total caloric intake. Feed analysis, including hay analysis, is recommended as high NSC content can occur in stressed pastures or grass hays despite our best efforts to control them. A common misconception is that alfafa is bad and grass hay is good – but this is not always true, as both can have an incorrect nutritional balance for your horse’s needs. When a hay analysis is not possible, soaking hay for 15-30min can reduce the NSC content, but the method is not guaranteed and other minerals and vitamins may be lost. Hay should also be weighed, as horses should be fed 2% of their body weight normally, and between 1.25 and 1.5% during a weight loss program. A feed scale or industrial hanging scale is an inexpensive and convenient method to ensure your horse is receiving just the right amount of hay. Supplements may be added to help control the glycemic fluctuations during the day, such as InsulinWise®, or ensure appropriate vitamin and mineral intake.
If your horse is thin but suffers from insulin dysregulation, alternative sources of calories should come from fat and protein. Fats such as vegetable oils, and high protein supplements, such as Hemp seed extract are very nutritious to provide energy without the glycemic spike seen with forage and grain.
Exercise
Exercise is important to help reduce the body fat content in EMS patients. As long as a horse is not suffering from an acute laminitis episode, walking, light exercise and regular work are recommended to promote weight loss.
Management
Routine farriery is important to help balance the mechanics of the foot that suffers or is at risk for laminitis. Trims may need to be more frequent, or pads and shoes may be recommended depending on the condition of the hoof. To further support the biomechanics of the foot, physiotherapy can improve movement and blood flow to the limbs. Kinesiotaping, cold laser, massage and acupuncture are some of the adjunct therapies that can improve the healing in the laminitic foot.
Is IR genetic and can we prevent it?
As certain breeds appear predisposed to the condition, research has been working towards identifying genetic markers that would predict those who will suffer from insulin dysregulation. Unfortunately, although breeds are predisposed, the genetic trait appears to complex. Without a clear inheritance pattern, no breeding recommendations or genetic tests can be offered at this time.
For more information:
Equine Endocrinology Group, Recommendations for the Diagnosis and Treatment of Equine Metabolic Syndrome (EMS)