Muscle Atrophy

What is muscle atrophy?

Muscle atrophy is not a single disease, it is simply the loss of muscle mass and it can have a range of clinical presentations and underlying causes. This complexity can make it a challenge to diagnose its underlying cause and to treat appropriately.

What causes muscle atrophy?

Muscular atrophy can be grouped into three broad categories based on the underlying reason for the atrophy. Muscle atrophy can be caused by:

  • A problem in the nerve innervating the muscle (neurogenic),
  • Damage to muscle fibers (myogenic) or
  • A systemic disease that causes generalized weight loss.

Muscle atrophy in Horses

When a muscle of a horse decrease in size, seemingly melting away , its known muscle atrophy, when this occurs, the primary concerns to a horse owner are whether the muscles will regenerate, returning to its normal size and shape , and how to treat the horse to help recover it.

The physical examination includes palpitation of muscle masses, observation of muscle mass symmetry and the notation of heat, pain, swelling, or other abnormalities in in a muscle.

Muscle disorders are a common cause of disability in horses. For many years, clinical manifestations such as muscle pain, exercise intolerance, weakness, and stiffness were believed to be caused by a single syndrome. However, in the past years a broad spectrum of muscle disorders have been recognized including glycogen and polysaccharide storage myopathies, malignant hyperthermia, mitochondrial myopathy, hyperkalemic periodic paralysis and others. For some, a specific mutation has been identified. Recognition of the myopathic clinical phenotype and thorough clinical, electrodiagnostic, and histological evaluations are essential to further our understanding of equine myopathies. Advances in understanding equine myopathies may potentially benefit other species including humans.

What is the best treatment for muscle atrophy?

  • The best treatment plan will depend on the underlying cause of your horse’s atrophy. In some cases this may involve oral treatment with medications such as vitamin E, Witanor Horse product, Pure enzymes and synbiotics, organic acid and synbiotics, these products will help absorbs more nutrients they are already receiving in hay, maintain a healthy gut which is the basis for a healthy horse, to help old or unthrifty horses bettr utilize nutrients, a probiotic may improve the efficiency of digestion and aid nutrient absorption in aged horses and others who have trouble maintaining weight, to help muscle recover its full form, additional therapies such as physical
  • rehabilitation therapy, therapeutic ultrasound and electrical muscle       stimulation may be indicated. Your veterinarian will guide treatment based on the underlying cause of atrophy.

Will my horse recover fully?

Muscle has a remarkable ability to regenerate and many horses do return to a normal muscle mass and full function, depending on its cause. Nerve damage may take up to a year to know whether it will fully regenerate which will be followed by a return of muscle mass. Immune mediated muscle atrophy can be dramatic but muscle mass often returns with treatment. In some cases, atrophy may have progressed to the point where connective tissue has replaced the muscle fibers, in which case the prognosis for full recovery of muscle mass is more guarded. The replacement of muscle fibers with connective tissue is often apparent on a muscle biopsy.

Organic acids and Enzymes

Organic acids and Enzymes

All animals require food to maintain bodily condition, provide the raw materials for growth, repair damaged tissues and provide energy for work or exercise.

The horse is a grazing animal, designed to eat almost constantly throughout the day. Their natural feed is grass and they have evolved to eat for 18 out of the 24 hours.

This helps prevent and mitigate feed allergies in horses. Enzymes aid in the repair of tissue and are beneficial when your horse is training. Enzymes play a role in virtually all body activities, each one having a specific function in the body. The enzymes in the body are actually an invisible activity or energy factor and not just the protein molecule itself. The reaction promoted by a particular enzyme is very specific. Therefore, because of cellular metabolism includes hundreds of different chemical reactions, there are hundreds of different kinds of enzymes.

As a natural grazer, consuming grain is not the most natural thing for a horse. Despite this, grains have been incorporated into the diet as a source of energy so that a horse can meet the energy demands of performance. Ideally, starch should be digested by enzymes in the small intestine, with as small an amount as possible being passed into the hindgut for continued digestion. Any amount that does pass to the hindgut for digestion could cause problems for the horse.

Application of organic acids can prevent the development of musty odor and mold in the hay that is not adequately dried. Most preservatives applied to horse hay contain organic acids that are the same as those found in the horse’s gastrointestinal tract. Propionic and acetic acid, the most common organic acids used in hay preservatives are produced naturally in the cecum and colon of horses as a result of microbial digestion of fibrous feeds. These organic acids can be used as mold inhibitors and applied when hay is not yet dry enough to bale safely but rain is coming and crop may be lost if not baled early. Research studies have shown that heating and molding of hay during storage is decreased with the use of preservatives.


  • May increase animal intake
  • Source of extra energy during hard work, competition, and long distance running
  • Improves horses performance and endurance
  • Boost immune system and prevents infection
  • Reduce feed allergy symptoms in your horse
  • Reduce malnutrition caused by poor nutrient absorption


The Microbiome

As they uncover the microbes in the ­intestine—which is as daunting a task as decoding the equine genome—­researchers are simultaneously attempting to determine what functions each serves. Currently, they believe on the whole the equine microbiome is responsible for:

  • Fermenting fiber in the hindgut to produce short-chain fatty acids (SCFAs), primarily propionate and butyrate, that the horse’s body absorbs into the bloodstream from the GI tract and uses for energy;
  • Boosting the horse’s immune ­system;
  • Producing antimicrobial products to control populations of pathogenic (disease-causing) microbes;
  • Physically excluding pathogens; and
  • Inhibiting the production and absorption of bacterial toxins (e.g., those produced by Clostridium difficile, a common cause of diarrhea in horses).

The Microbiome during Disease, Stress

The intestinal microbiome is comprised of quadrillions of microbes, and keeping them all happy is imperative to horse health. In adult horses, colic and colitis, laminitis, foal heat diarrhea, and equine grass sickness are the most notable consequences of disrupting the equine intestinal microbiome.

To help characterize the exact changes in the equine intestinal microbiome under certain conditions, one research group, including Christopher Proudman, MA, Vet MB, PhD, Cert EO, FRCVS, of the equine division of the University of Liverpool’s Department of Veterinary Clinical Sciences, in the United Kingdom, collected and analyzed samples from the large intestines of horses:

  1. Maintained on pasture;
  2. Consuming a concentrate diet; or
  3. Consuming a concentrate diet and diagnosed with simple colonic ­obstruction and distension (SCOD), a prevalent form of the diet-induced intestinal disease.

Keeping the Microbiome Happy

One potential way to maintain the equine intestinal microbiome’s health and integrity is through probiotic administration. Probiotics are “direct-fed microbial,” or live yeast and/or bacteria believed to help maintain or restore the health of the intestinal microbiome. Probiotics’ potential mechanisms of action include boosting the horse’s immune system, producing some antimicrobial products, excluding disease-causing microorganisms, and inhibiting bacterial toxins. Examples of probiotics include bacteria and yeast such as Bacillus subtilis, Bacillus licheniformis, Saccharomyces cerevisiae, Lactobacillus acidophilus, Enterococcus faecium, Lactococcus lactis, and Bifidobacterium longum, among others.

“A further understanding of the horse’s  intestinal microbiome will help (owners and veterinarians) manage these animals during a critical part of their lives. ”

Dr. Scott Weese


Yeast Cell Wall

Are live strains of the yeast, Saccharomyces cerevisiae, are used in animal nutrition to enhance fiber digestion in both ruminants and non-ruminants. These strains have the ability to metabolize nutrients in an anaerobic environment and promote the growth of beneficial bacteria, including those that can utilize lactic acid.

Beneficial effects have also been seen in mares during gestation with regard to milk quantity and quality, resulting in faster growing foals. As the fetus grows in size during the 3rd trimester of gestation, the room available for food in the mare is significantly reduced, which can result in loss of body condition. Improving nutrient digestibility at this stage is important to minimize loss of condition of the mare.

Yeast also increases efficiency of energy production in animals like cattle and horses that ferment fiber via microbial breakdown. Although the exact mechanism remains elusive, one theory is that the yeast feeds the beneficial bacteria that convert fiber into energy in the cow’s rumen and the horse’s hindgut.

Although all horses can benefit from more efficient energy production, this is of extra importance to senior horses, whose ability to break down fiber eventually decreases, sometimes resulting in declining body condition.

Maintaining Balance

For example, if a horse who usually eats mostly hay gets more pasture grass one day, the organisms who thrive on that particular mix of foodstuffs thrive while their counterparts decline. Most of the time, these fluxes are harmless and self-correcting.

There are many other factors that can alter the microbe levels in the gut. “Anything that changes the pH, interferes with gut motility or affects the fluid levels—all would change the balance,” says Kathleen Crandell, PhD, a nutritionist with Kentucky Equine Research. In addition to sudden changes in diet, specific events that can upset the microflora levels include the administration of oral antibiotics, dehydration, fever and ingesting feed tainted with molds or bacteria.

Even stresses, such as those associated with travel and competition, can have an effect. Going on the road tends to disrupt the horse’s routine: He may not drink as much, he may be getting different hay or grasses, his anxiety may keep him off his feed entirely for a time. Also, stress produces measurable changes in levels of hormones, body temperature, immune responses, heart rate and other functions, all of which may cause the populations of beneficial bacteria to drop.

if a probiotic is helping to keep your horse happier and healthier, there’s no reason not to keep offering it.

What probiotics can do for your horse?

Probiotics have been studied for more than a century, and their use is now common for food animals, such as cattle. For the past decade or so, veterinarians have been administering them to horses, too, to aid recovery from serious intestinal illnesses. Described in academia during the 1960s and ’70s as any organism or substance that benefited the intestinal microbial balance, the generally accepted meaning today is “a live microbial supplement which beneficially affects the host animal by improving its intestinal microbial balance.”

<em><strong>“The main goal of administering probiotics is to manipulate the normal intestinal flora in such a way that is beneficial to the health of the horse,”</strong></em> Swyers says. “With that said, researchers are looking for ways that we can use probiotics to improve the digestibility of feedstuffs, reduce the incidence of digestive upsets that could lead to colic or diarrhea, and act as a natural alternative to administering antibiotics, just to name a few areas of interest.”

The inside of a horse’s gut is home to colonies of bacteria, protozoa and fungi, often referred to en masse as the intestinal flora or microflora.<em><strong> “It has been estimated that there are approximately five billion organisms per gram of digestive fluid in the mammalian digestive tract,”</strong></em> Swyers says.

These tiny organisms are engaged in the usual activities of life: consuming one set of substances, excreting another and reproducing. Together they create a complex, symbiotic web. The excretions, called metabolites, produced by one organism may feed another, which in turn produces a third that may be a nutrient necessary to the horse’s life. For example, the complex molecules in starches and cellulose cannot be directly absorbed by the horse’s intestine—they must first be broken down by the flora into components that he can use.