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The equine world has intersected with the coronavirus pandemic in more ways than one. In 2020, researchers in Costa Rica formulated a COVID-19 treatment based on the antibodies that horse serum could generate in order to fight SARS-CoV-2 infections. This research effort would eventually be adopted by scientists in Argentina, Brazil, Sweden, and India; in the latter country, clinical trials to switch from horse plasma therapy to a medication made with treated drug serum were underway as of August 2021. Another aspect of the pandemic that had a direct impact on the equestrian world was related to quarantine and lockdown restrictions that were imposed by health officials in many countries starting in March 2020; in some cases, these measures resulted in horses suffering from muscle atrophy.

When pandemic restrictions were first imposed, the International Federation for Equestrian Sports reminded members and horse keepers in general about the risk of muscular atrophy in their animals. According to Emmanuelle van Erck , a horse expert based in Belgium, horses are able to "stay in shape" for about a month even if their level of physical activity ranges from negligible to null. After four weeks of zero mobility, problems associated with muscle atrophy start becoming noticeable, and they could worsen quickly.

Equine Muscle Disease Dr. Erck emphasized that horses kept in stables should be allowed to get exercise on daily basis, particularly if they are older, in order to prevent muscular atrophy. In the case of yearlings, they only need to exercise a couple of times a week; since their muscle fiber is still developing, atrophy is less likely to affect them immediately, but it is always better for them to enjoy as much galloping as they can handle before they enter their adult stages. Atrophy is just one of various diseases that can affect equine muscle fibers; the rest include:

Fasciculation: More commonly known as twitching, these contractions may be caused by neurological or biochemical conditions. Lameness: This is when horses are not able to use their muscles efficiently because of conditions that are not related to their joints or cartilage tissue. Rhabdomyolysis: This painful condition, which is characterized by myalgia episodes, stiff muscles, and cramps, is often related to inadequate muscle cell production. Weakness: Loss of muscle strength is more problematic in horses than humans, and this is related to the larger amount of muscle mass. Some horse keepers refer to atrophy as wasting because the loss of muscle mass can actually be seen. Atrophy is not always systematic; in some cases, it may only affect just a single muscle or a group.

Causes of Muscle Atrophy in Horses As previously mentioned, atrophy can be a result of adult horses not getting the daily exercise they need. It should be noted that we are talking about proper exercise instead of just leading horses out of the stable so they can walk over to their grazing area. Free-range horses that have the advantage of large habitats are able to take care of exercising on their own; this may involve steady walks, a bit of trotting, some galloping, and jumping if available, but the combination of these activities may last several hours.

In addition to the above, the following conditions may also be causative of atrophy:

Vitamin E deficiency Malnutrition Muscle fiber damage Neurological issues Unbalanced saddles Horse keepers who witness cases of severe muscle atrophy will think that their animals are wasting away as if they had tuberculosis or some kind of incurable autoimmune disease. This is when it is important to remember that horses are generally pretty resilient beasts; since muscle mass is inherent and intrinsic to their survival, there is a good chance of tissue regeneration once the underlying problems are treated or otherwise solved.

Horse muscular atrophy (HMA) can also occur when a single muscle or a group end up being overworked through riding. This most often occurs after a horse has performed strenuous work. The cause of HMA is not completely understood, but the main suspects are muscle overwork and improper nutrition. Other diseases that can cause muscle atrophy include laminitis, kidney failure, heart disease, muscle abscesses, and tumors.

When Unbalanced Saddles Cause HMA Anyone who has been into horse riding for more than a few days knows that improper saddle fit, inadequate padding, and incorrect cinching can lead to many equine health problems. Saddlers will always tell you that fitting horse tack is a constant exercise in making sure that the animal will be comfortable and healthy; when this is not the case, you may as well just fit your horse with a nice blanket pad and learn to ride bareback.

As heartbreaking as this may sound, saddles that are not balanced are one of the main causes of HMA in the equestrian world. The best way to understand this is to think about how we would react to a broken backpack strap when we go on a mountain hike. Unless we are able to either ditch the pack or fix the strap, we would now be dealing with an unbalanced load, which we will likely try to counteract by contracting the muscle tissue around the unbroken strap. Physiologically, the increased pressure will start using up too much oxygen and nutrients, which at some point will turn deficient. Once we complete our hike with a broken strap, the affected and overworked muscle will be left feeling painful and weak. If we never get around to fixing that strap and go on daily hikes with this unbalanced weight on our shoulders, we will suffer muscle atrophy because of the aforementioned deficiency in oxygenation and nutrients.

HMA and Saddle Fit Trauma A saddle that pinches the skin and puts more weight on a muscle group will eventually cause HMA. Horse keepers should never forget that both saddles and riders are not natural to horses; this is why proper fit of saddles and all horse tack pieces is crucial to equine health. Saddle fit trauma is a veterinarian term that describes the excessive pain horses are subject to when tack causes extreme discomfort, and HMA happens to be one of the signs indicative of this kind of trauma. The cause is usually the tack not being properly fitted to the horse's anatomy, causing either a lack of space around the horse's shoulders, or a heavy fit that causes trauma to the shoulders.

In some cases, the gullet channel could be too narrow; in other cases, the angle of the shoulders fails to provide a good match to the angle formed by the base of the tree and the gullet. Whenever the saddle seat panel does not make a line parallel to the ground, you can count on the saddle being out of balanced, and the uneven weight distribution will surely increase the potential of HMA unless the problem is rectified.

HMA Treatment Options Depending on the underlying causes of HMA, different therapeutic approaches may be recommended. We already discussed easy remedies that involve increasing the daily activity of horses that spend too much time in the stable; likewise, we already mentioned how correcting the fit and cinch of saddle and tack can go a long way in preventing HMA. Let's look at other treatments:

Improved nutrition - Vitamin E deficiency has been linked to faster muscle tissue recovery. In addition to prescribed injections of vitamin E, special horse treats made with carrots, raisins, apples, and beets are usually enriched and fortified with healthy vitamins and minerals. Pergolide - This medication, which was originally developed to treat Parkinson's disease in humans, has proven effective in the treatment of HMA when it is related to Cushing's disease. Corticosteroids - These injections are usually recommended when HMA is caused by osteoarthritis, which some horses will suffer to various degrees as they get older