Equine Metabolic Syndrome is an endocrinopathy (hormone related disease) that affects horses, ponies and donkeys. It is characterised by 3 main features; Obesity, and/or regional adiposity (fat deposits in certain areas, ie. the crest), Insulin resistance, and Laminitis. There is a large genetic component to EMS, so when a genetic predisposition is teamed with improper management, the syndrome is likely to develop.
The diagram below shows insulin regulation in a normal horse.
Testing for EMS
There are several tests available for diagnosis of EMS. One of the most accurate tests that we choose to use is the ‘Oral Sugar Test’. This is a minimally invasive test that involves fasting the horse or pony overnight, taking baseline insulin and glucose samples, and then repeating the samples following a meal.
Treating & managing EMS
Whilst there are several ‘off-label’ medications available to aid in the management of EMS, correct feeding and exercise are the most important elements in maintaining affected horses. Diets which are low in starch and high in structural carbohydrates (ie. low quality roughage) are recommended. Exercise will also aid in weight loss and help with metabolism.
Case Report
Equine Metabolic Syndrome in an 8 Year Old Welsh Pony
‘Bubbles’ is an 8-year-old Welsh A pony who we have recently been investigating for intermittent episodes of laminitis, which she has endured since she was only 2 years of age. She also has a long ‘family history’ of laminitis and most of her relatives have the EMS ‘body type’. Despite meticulous management by her owner, it became apparent that Bubbles was incredibly susceptible to laminitis – even ingestion of the smallest amount of starch (ie. the occasional pick of spring grass) was enough to cause an episode.
Bubbles was not typical in her presentation of EMS, as she was relatively lean when compared to the classic ‘EMS body type’. However, given her extreme sensitivity to sugar, and her susceptibility to laminitis, an oral sugar test for EMS diagnosis was recommended. The results came back positive, meaning that she has a very poor response to insulin (see diagrams). Although as mentioned, Bubbles was not of the typical EMS body type, we could not rule out insulin dysregulation without objective diagnostics. Bubbles’ feet were also radiographed (see photos below) as part of her work-up, which allowed us to get an idea of where her pedal bone was sitting inside the hoof capsule. The radiographs were then discussed with her trimmer, and a corrective trimming plan was created.
As you can see from the radiographs (left and right), there is significant ‘rotation’ of the pedal bone within the hoof capsule. This is a typical finding with a chronic laminitis case.
Now that we have a definitive diagnosis of EMS for Bubbles, she has been placed on an even stricter diet and exercise regimen than she was previously. She is currently going very well on this program, however if laminitis develops again despite meticulous management from her dedicated owner, she will be prescribed medications to further help her condition. This case highlights that even despite the best care, ponies with endocrinopathies such as EMS or PPID are often highly susceptible to laminitis. It is therefore important to consider EMS testing when working up any laminitis case, particularly if there is no other underlying cause. Testing for PPID (Equine Cushing’s Sydrome) may also be included as part of a laminitis work-up, depending on the age of the horse and the presence of other signs.