Today is going to be a double path round day, since we have two related diseases to discuss! Both were a common request. This post is on ๐๐ช๐ฎ๐ข๐ง๐ ๐ฆ๐๐ญ๐๐๐จ๐ฅ๐ข๐ ๐ฌ๐ฒ๐ง๐๐ซ๐จ๐ฆ๐ (EMS).
๐๐ก๐๐ญ ๐ข๐ฌ ๐ข๐ญ?
๐๐๐ is an endocrine dysfunction of ๐ข๐ง๐ฌ๐ฎ๐ฅ๐ข๐ง, the bodyโs main hormone it uses to get ๐ ๐ฅ๐ฎ๐๐จ๐ฌ๐ (the main sugar used for energy) into cells. In normal horses, insulin levels increase when blood glucose levels increase, to help store the glucose away in cells and provide the cells energy. In EMS horses, they typically have ๐ก๐ฒ๐ฉ๐๐ซ๐ข๐ง๐ฌ๐ฎ๐ฅ๐ข๐ง๐๐ฆ๐ข๐, which is when there are high levels of insulin despite normal levels of blood glucose.
๐๐ก๐จ ๐ ๐๐ญ๐ฌ ๐ข๐ญ?
This disease typically develops in horses between 5-15 years of age, and it is most commonly obese horses that develop it. The breeds that are predisposed are typically the โeasy keeperโ breeds like ponies and Quarter Horses.
๐๐ก๐๐ญ ๐๐๐ฎ๐ฌ๐๐ฌ ๐ข๐ญ?
The underlying cause of EMS is not known, however it seems strongly linked to obesity. However, the main outcome is hyperinsulinemia, which can have significant effects in equines!
๐๐ก๐ฒ ๐ข๐ฌ ๐ญ๐ก๐ข๐ฌ ๐ ๐ฉ๐ซ๐จ๐๐ฅ๐๐ฆ?
Prolonged high levels of insulin in the blood has been strongly associated with the development of ๐ฅ๐๐ฆ๐ข๐ง๐ข๐ญ๐ข๐ฌ, which is inflammation of the ๐ฅ๐๐ฆ๐ข๐ง๐๐, the major connective tissue between the ๐๐จ๐๐๐ข๐ง ๐๐จ๐ง๐ (the main bone within the hoof) and the hoof wall. It is currently not known why high levels of insulin causes laminitis, but it is believed to be related to changes in blood flow to the foot, and possible activation of ๐ฆ๐๐ญ๐ซ๐ข๐ฑ ๐ฆ๐๐ญ๐๐ฅ๐ฅ๐จ๐ฉ๐ซ๐จ๐ญ๐๐ข๐ง๐๐ฌ๐๐ฌ, which are enzymes that break down ๐๐จ๐ฅ๐ฅ๐๐ ๐๐ง (a main structural protein in the laminae).
Laminitis is extremely painful for horses, as they have a large amount of nerves in the laminae. When the laminae have separated, the coffin bone essentially falls victim to gravity and the weight of the horse standing on it. There are two possible outcomes from this: rotation, and sinking.
Rotation happens because of the ๐๐๐๐ฉ ๐๐ข๐ ๐ข๐ญ๐๐ฅ ๐๐ฅ๐๐ฑ๐จ๐ซ ๐ญ๐๐ง๐๐จ๐งโs attachment to the coffin bone. This tendon is the main tendon the horse uses to bend its leg, and it uses the coffin bone as an anchor. Typically, the laminae at the front of the hoof begin to separate, allowing the coffin bone to rotate and point downward. If left uncontrolled, the bone can actually poke through the bottom of the hoof. Mega ouch!
Sinking is a really severe form of laminitis, where the laminae all around the perimeter of the hoof have begun to separate. In this case, the entire coffin bone sinks down into the foot, getting closer to the ground. Again, if left untreated, this can lead to the bone poking out of the bottom of the foot.
๐๐จ๐ฐ ๐ข๐ฌ ๐ข๐ญ ๐๐ข๐๐ ๐ง๐จ๐ฌ๐๐?
Veterinarians can have a pretty good idea if a horse has EMS just by looking at them. Horses will be obese, with ๐ซ๐๐ ๐ข๐จ๐ง๐๐ฅ ๐๐๐ข๐ฉ๐จ๐ฌ๐ข๐ญ๐ฒ, which are large fat deposits in the neck and over the tailhead. Horses may also have signs of laminitis.To confirm the diagnosis, veterinarians will test for PPID to rule it out (todayโs other post!) and test for ๐ข๐ง๐ฌ๐ฎ๐ฅ๐ข๐ง ๐ซ๐๐ฌ๐ข๐ฌ๐ญ๐๐ง๐๐. To test for insulin resistance, the veterinarian will give the horse corn syrup, and measure insulin levels in the blood in response to the sugar meal. Remember how insulin should go up with increased blood sugar? If the insulin level does not go back down appropriately, then the veterinarian can diagnose ๐ข๐ง๐ฌ๐ฎ๐ฅ๐ข๐ง ๐๐ฒ๐ฌ๐ซ๐๐ ๐ฎ๐ฅ๐๐ญ๐ข๐จ๐ง characteristic of EMS.
๐๐จ๐ฐ ๐ข๐ฌ ๐ข๐ญ ๐ญ๐ซ๐๐๐ญ๐๐?
The mainstays of treatment for EMS are diet and exercise. Since EMS is so closely linked to obesity, diet and exercise to help the horse lose weight can help the horses immensely. The main diet change is to reduce the amount of sugar the horse is consuming, to help prevent insulin spikes in the bloodstream. If diet and exercise arenโt working, medications like ๐ญ๐ก๐ฒ๐ซ๐จ๐ฑ๐ข๐ง๐, to increase the bodyโs metabolism, or ๐ฆ๐๐ญ๐๐จ๐ซ๐ฆ๐ข๐ง, a drug to prevent high blood glucose, can be used as part of the horseโs treatment plan.
๐๐จ ๐ฐ๐ก๐ฒ ๐๐ข๐ ๐ฒ๐จ๐ฎ ๐ฉ๐จ๐ฌ๐ญ ๐๐จ๐ญ๐ก ๐จ๐ ๐ญ๐ก๐๐ฌ๐ ๐๐ข๐ฌ๐๐๐ฌ๐๐ฌ ๐ญ๐จ๐๐๐ฒ? ๐๐ก๐๐ฒ ๐๐จ๐งโ๐ญ ๐ฌ๐๐๐ฆ ๐ฌ๐ข๐ฆ๐ข๐ฅ๐๐ซ ๐๐ญ ๐๐ฅ๐ฅโฆ
Good question! Because both diseases can cause laminitis and insulin dysregulation, and can actually occur at the same time in the same horse, some people think they are the same thing. However, they do have very different root causes and treatment plans. This is why itโs important to speak to your veterinarian about any changes you see in your horsesโฆ sometimes Dr. Google can lie to you!
๐๐ก๐จ๐ญ๐จ๐ฌ
1) A horse showing ๐ซ๐๐ ๐ข๐จ๐ง๐๐ฅ ๐๐๐ข๐ฉ๐จ๐ฌ๐ข๐ญ๐ฒ, with excessive fat over the rump and neck.
2) An X-ray of a laminitic hoof showing how rotation and sink (founder distance) can be measured, to help identify how severe the laminitis is.
3-4) Severe cases of laminitis, one where the coffin bone has almost poked through the sole, and one where the bone is completely through.
5) Another severe case of laminitis displaying a different โoptionโ for the coffin boneโฆ complete destruction! This bone has undergone ๐ฅ๐ฒ๐ฌ๐ข๐ฌ and no longer has a nice pointed tip like it should have.
๐๐จ๐ฎ๐ซ๐๐๐ฌ
Kritchevsky, J.E. Overview of Equine Metabolic Syndrome. Merck Veterinary Manual. 2019.
Photo 1 courtesy of Wikimedia Commons.
Photos 3-5 courtesy of Noahโs Arkive.
