While most stallions and some breeds have a more prominent crest to start with, (eg Welshies & Spanish breeds), when horses develop EMS, the crest of their neck enlarges further– an extra ‘ridge’ appears on top of their normal neck profile – hence the term ‘cresty’.
They also develop other sub-cutaneous (just under the skin) swellings, above the eyes, behind the shoulders, at the tail-head, on the sides of the rump, these are referred to as ‘fat pads’ but they are more like ‘fluid lumps’. They give these horses that ‘lumpy look’! (See picture above)
We always used to wonder : How is it that the ‘crest’ of the neck can suddenly go from feeling comparatively soft and wobbly to ‘standing up’ and hard as a rock in a very short time, like over-night?
We learned from Dr Deb Bennett PhD (who has conducted dissections of horses with EMS), that “the horse's "crest" is made of fibro-fatty sub-cutaneous (adipose) tissue similar in texture to high-density foam”.
Like foam, the crest tissue can take up fluid like a sponge; so under certain metabolic conditions it becomes ‘turgid’ ie it fills with fluid which is ‘leaking’ from tiny capillaries, until it is hard as a rock.
This rapid hardening of the ‘crest’ tends to happen a day or two after rainfall events, potentially at any time of the year but more frequently in spring and autumn conditions which favour growth spurts of the grass.
Many people make a point of monitoring the hardness of their horse’s crest daily because it is a major indicator that a laminitis episode is imminent. Since laminitis is a disaster this is like living on the brink of disaster. The fact that the horse has a ‘cresty’ neck is reason enough to make urgent changes to diet and management.
If urgent action isn’t taken the hardening of the crest is closely followed by ‘stiffening’ of movement, the presence of a digital pulse and sore feet (being ‘footy’), tender on hard ground, ie laminitis.
The crest ‘softens’ once nutrient imbalances are corrected. This is why feeding EMS horses isn’t just about low sugars and starches. It is also about correcting mineral imbalances which cause the puffiness and swellings.
It is best not to focus on any one mineral like magnesium, there are many other equally important minerals, vitamins and amino acids which need to be supplied because they all interact and help one another. It is about lowering intake of some nutrients and increasing intake of others.
Laminitis & EMS
Horses who show signs of Equine Metabolic Syndrome are prone to laminitis any time of the year but the risk goes up in spring and autumn.
Laminitis aside, a horse with EMS is not a healthy horse but the condition can be successfully reversed with dietary and lifestyle adjustments. Understanding the syndrome is Step 1.
Most people know these horses need a diet which is low in sugars and starches (<10%) and an increase in exercise but EMS is not the same as being over-weight.
Some EMS horses are over-weight and some are not but EMS horses are distinguishable by their ‘lumpy look’ with their ‘cresty’ neck and the extra ‘fat’ pads above the tail-head, behind shoulders and on the sides of the rump. (See picture top left) They are also prone to ‘puffiness’ in general, swollen sheaths and swellings in front of the udders.
Thus EMS is actually a ‘metabolic disorder’ due to malnourishment – not because of insufficient quantities of food - rather it is caused by not eating the right food.
This is why starving the EMS horse by keeping him in ‘jenny craig’ type paddocks does not reverse EMS and does not prevent them from tipping over into laminitis. Severely limiting forage intake (either by keeping the horse on very short grass, not supplying enough hay, or by spending long hours in a grazing muzzle) is merely reducing the amount of unsuitable food going in which is harmful to the horse both physically and mentally.