Can you tell if a horse has EMS (Equine Metabolic Syndrome) by looking at him? It’s not as easy as you may think it is.
The usual description is a clearly overweight horse with a large fatty neck crest, filling of the fossae above the eyes with fat, patches of lumpy fat. The grey below has these patches most visible on his hindquarters but they may be located anywhere. Except for the classical inward curving ear tips, there is no outward indication this horse is an Arabian.
from: Equine Podiatry and Lameness Centre [AU]
Normal Anglo-Arabian for Comparison
However, less than 50% of EMS horses are overweight at time of diagnosis, especially if they are laminitic. While EMS horses may gain weight more easily, whether or not they are overweight is still a matter of how many calories they are getting. They can be kept a normal weight by feeding the correct number and type of calories. They don’t have to be starved.
The one physical characteristic most likely to be found on an EMS horse is a fatty crest. The Friesian cross above has a normal body condition score in general but has a fatty deposit on his neck. Filling of the orbital fossae, the depressions above the eyes, is also very common with EMS.
While it is the most reliable physical characteristic, even a large crest does not guarantee the horse has EMS. This young Quarterhorse had normal insulin testing:
Being obese, even very obese, also does not guarantee the horse has EMS. In one field survey, only approximately 35% of the most overweight horses actually had EMS. The only way to tell for sure is laboratory testing.
The most common characteristic shared by EMS horses is laminitis but laminitis also needs to be carefully diagnosed. A horse being fat and foot sore does not automatically equal EMS. There are many other causes of hoof pain besides laminitis.
The presence of hoof rings is not a reliable indicator of laminitis since many different things can cause rings to form. Laminitis is only the likely cause when rings diverge, being wide at the heels and close together on the dorsal hoof wall:
from: Chestofbooks – Laminitic Rings
Rings can also form from any physiological disruption such as foaling, illness, extreme work or diet change. Those rings are of equal width around the hoof wall.
from: Chestofbooks – Physiological Rings
Other nonspecific outward indications of laminitis include strong arterial pulses to the hoof, reactivity to hoof testers and increased hoof wall temperature. These things may or may not be present in a laminitic horse (more likely with acute laminitis) but even when found they are not 100% specific for laminitis.
“Looks can be deceiving” is as true for EMS as anything else. If you suspect your horse is affected, get your veterinarian involved. The best results start with an accurate diagnosis.
Eleanor Kellon, VMD