Adding herbs to the management program of your insulin resistant horse can help him lead a longer, healthier life.

The number of insulin resistant horses is on the rise. It may partly be due to genetics and breeding, but the way we manage our horses and ponies is also a culprit. In wild equines, high levels of blood glucose, whether obtained from the diet or because of insulin resistant cells, will eventually be converted and stored as fat. But unlike their wild cousins, our pampered domesticated horses are never required to go through the scarce food times of winter. Instead, we make sure they are well fed and blanketed, then we turn them out onto rich pastures in spring where they have no need to expend any energy searching for food.

The Skinny on Insulin Resistant Horse

Experts believe IR mimics Cushing’s disease in many ways, although the horse does not have the benign pituitary adenoma present in the Cushing’s animal.

Diagnosis revolves around clinical signs (abnormal body fat distribution, abdominal fat, cresty neck, fatty shoulders, geldings with swollen sheaths), in combination with blood tests. Blood samples are usually taken for insulin and glucose, and sometimes triglyceride (component of fat) levels.

Although affected animals may be overweight, this is not always the case. Most tend to be “easy keepers” or resistant to losing weight, or they may have been overweight as youngsters. Founder is usually a feature at some point, with hoof changes such as founder rings, or an expansion of the white line suggesting some founder has occurred, even despite the absence of apparent foot pain.

Understanding Cortisol

Normally, when carbohydrates are digested they are converted into glucose, which is absorbed through the gut wall and enters the bloodstream. Here, the hormone insulin acts like a “key”, allowing glucose to enter cells where it is used as an energy source by the body. Conversely, when glucose levels in the body drop, the production of insulin stops.

Body fat was once thought to be just an energy reserve and protector of vital organs. However, certain types of body fat, especially those found in the abdomen, are now thought to be actively involved in a number of metabolic processes, including cortisol production. One consequence of increased body fat is that it can lead to an increase in the level of cortisol. Cortisol is a natural steroid hormone; among its many functions, it inhibits the action of insulin and provokes the flight-or-fight response to stress. With high body fat stores, cortisol production levels remain high and are not switched off, leading to increased circulating levels of cortisol. This further inhibits the action of insulin, encouraging some of the cells to become insulin resistant and preventing the normal uptake of glucose by these cells, leading to high circulating blood glucose levels. The body still needs an energy source to function correctly, however, so the liver starts to break down stored fat reserves (gluconeogenesis).

How Can Herbs Help Insulin Resistant Horses?

Many herbs that can be used for the insulin resistant horse are the same ones I would prescribe for an individual suffering from type 2 diabetes, a condition very similar to insulin resitance, which produces many of the symptoms we see in insulin resistant horses (obesity, lethargy, poor circulation, muscle wastage, etc.).

It is important that any herbal supplementation be used in conjunction with a steady (gradual) fitting up/weight loss program. Regular exercise is essential to encourage loss of body weight, and a greater muscle mass will help with fat metabolism (muscles burn more calories). Daily turnout is vital – horses and ponies were designed to graze while on the move, which again encourages the burning of calories. The lifestyle of your horse plays just as important a role as dietary management.

Helpful Herbs for Insulin Resistance

Artichoke Leaf (Cynara scolymus) is hypoglycemic (reduces blood sugar levels), and hypolipidemic (reduces serum lipid levels). Artichoke significantly reduces serum cholesterol and triglyceride levels. Artichoke is also a prebiotic that will help encourage production of “good” hind gut bacteria, and improve the liver function necessary to help break down stored fat.

Psyllium husks (Plantago major) contain a constituent known as mucilage (a plant polysac-charide). Mucilages are a class of soluble fiber and psyllium in particular has been well studied and shown to be effective at lowering blood cholesterol, insulin and glucose levels. The plant has also been shown to offer an anti-inflammatory and healing action on the digestive tract as well as acting as a prebiotic, enhancing levels of beneficial bacteria in the gut. These actions are particularly relevant, as it has been suggested horses may struggle to absorb nutrients from their food if the integrity of the gut is compromised. Lack of nutrient absorption has been linked to the onset of some forms of founder.

Fenugreek (Trigonella foenum – graecum) is hypoglycemic and hypolipidemic. It reduces blood sugar and cholesterol levels in diabetics. Contains the constituent galacto-mannan, which aids with fat digestion. Milk thistle (Silybum marianum) is a cholagogue, which means it stimulates the production and flow of bile, aiding in fat digestion.

Milk thistle is hepatoprotective and has a strong antioxidant action (offering ten times the antioxidant action of vitamin E). Garlic (Allium sativum) is hypoglycemic and hypolipidemic. It effectively reduces the levels of glucose in the bloodstream as well as lowering blood lipid levels and total cholesterol.

Garlic has been shown to help clear fats accumulating in arteries, and it is used extensively for diabetes. Ginger (Zingiber officinale) contains gingerol, which has been shown to have prolonged hypoglycemic activity. Ginger is also a vasodilator and strong circulatory stimulant that will help encourage healthy blood supply to vital organs and limbs.

Goats rue (Galega officinalis) is hypoglycemic, and like psyllium it inhibits the absorption of glucose from the gut, thereby reducing sugar levels in the bloodstream. The herb also potentiates the effects of insulin, promoting uptake of glucose by the cells.

Kelp (Fucus vesiculosis) is anti-obesity, and is rich in organic minerals, biotin and methionine (needed to ensure healthy hoof growth) and magnesium (low levels of magnesium have been linked to IR). It contains high levels of other minerals, trace elements, amino acids and vitamins.

Mint (Mentha piperata) is a digestive carminative and soothing to the digestive system. Mint is also a good source of potassium and magnesium.

Nettle (Urtica dioica) is a circulatory stimulant, rich in vitamin C, iron, sodium and dietary fiber. Cleansing and anti-diabetic, nettle will stimulate blood supply to vital organs and in particular to the limbs and feet.


Hilary Self is co–founder of Hilton Herbs Ltd, a company that for the last 22 years has been at the forefront of manufacturing and formulating herbal supplements for animals. Hilary is a Medical Herbalist and a member of the National Institute of Medical Herbalists. Hilary is responsible for all the company’s formulations and for clinical research into the use of herbs for animals. In 2004 she received the Nigel Wynn award from the National Institute for innovative projects in herbal medicine, in recognition of clinical trials she undertook into the application of herbs for horses with Cushing’s disease. Hilary is also a member of the USA’s National Animal Supplements Councils (NASC) Scientific Advisory Committee. hiltonherbs.com

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