Donkey Metabolic Syndrome

Endocrine and metabolic diseases are frequent in donkeys. Because of their efficient energy use, obesity is frequent in donkeys, often associated with insulin dysregulation and endocrinopathic laminitis. Donkey Metabolic Syndrome (DMS) is a recently recognized condition that seems to be highly prevalent in donkeys of different breeds in developed countries or where food is readily available. DMS shares key features with equine metabolic syndrome (EMS), including obesity, ID, and endocrinopathic laminitis. Similar to horses and ponies, not every obese donkey has ID and lean animals can be affected.

Donkeys are considered easy keepers, with lower energy requirements than horses. They are more energy efficient than horses and access to calorie-rich diets, including high-quality grass, grain, or feed concentrates, easily leads to obesity and associated complications.

Clinical signs

Obesity, laminitis and insulin dysregulation are the main clinical signs observed in donkeys with DMS.

Laminitis : hoof anatomy differs between donkeys and horses, with different radiology findings and measurements.

Obesity : Because donkeys and horses have differences in fat distribution and neck morphology, species-specific protocols should be used.

Neck score system in donkeys. Grading from 0 (thin) to 4 (cresty neck).

Obesity in donkeys. Note the fat distribution along the side, dorsum, and nuchal ligament (body condition score of 9 out of 9; neck score of 4 out of 4).

Insulin Dysregulation : Basal glucose and insulin concentrations, as well as dynamic tests, are the main methods used in the diagnosis of ID in donkeys. Factors that could interfere with the diagnosis of ID diagnosis include stress, carbohydrate-rich diets, physical activity, pain, transport, endocrinopathies (PPID), concurrent diseases. We recommend dynamic tests to diagnose ID in donkeys.

Treatment

In order to promote weight loss, caloric restrictions and increased physical activity are central to success. Because of their ability to subsist on poor-quality feedstuffs, dietary management should rely on low-quality hay (<10% nonstructural carbohydrates), eliminating grain, concentrates, and access to carbohydrate-rich pastures. Commercially available diets to manage ID and obesity in horses may not be appropriate for donkeys.

Whenever possible, and depending on the level of laminitis, access to a paddock to promote physical activity is indicated. However, animal displaying current signs of laminitis should be confined. Long stays in paddocks are more appropriate than quick walks, which can be counterproductive. Grazing should be avoided early morning, after rainfall, and when grass is expected to be rich in soluble carbohydrates. Grazing muzzles could be used with caution in obese animals, although some vets do not recommend their use in donkeys because of their eating habits, curious behavior, and risk of hyperlipemia.

Weight loss in donkeys should be promoted slowly to avoid metabolic complications. A 1% to 2% body weight loss per month is a reasonable goal, although this is arbitrary and specific weight-loss protocols have not been developed. Weight loss in donkeys may be a very slow process.

The pharmacology of the drug metformin to promote weight loss has not been investigated in donkeys, but we have used it with some success.

It is important to note that whilst weight loss is an important aspect of managing donkeys with DMS, these animals should not be starved or have their feed dramatically reduced. Doing so puts them at a high risk of a potentially fatal disease known as Hyperlipemia.