Draft Horses are the gentle giants of the equine world. These massive horses were originally bred for pulling. They have short backs and well-muscled hindquarters that make them ideally suited for pulling heavy loads. Their placid and willing temperaments make them easy to work with. They were an integral part of early farming and industrial life, as well as instrumental during times of war. They continue to be an important part of farming life today, as well as enjoyed for their skill in carriage driving and in sport such as pulling competition.

There are many breeds of draft horse, but all share common characteristics of strength and calm temperament. The most common draft breeds recognized today include: Shires, Belgians, Clydesdales, Percherons, Friesians, Brabants, American Cream Draft, Fjords, Spotted Drafts, Haflingers, Gypsy Vanners, and the Suffolk Punch. Many of these breeds stand 16-19 hands tall and can weigh up to 2200 lbs.

Draft horses have their share of medical problems, some of which are quite specific to the draft horse or certain breeds of drafts.

Equine Polysaccharide Storage Myopathy (EPSM)

Probably the most widely known condition that affects Draft breeds is Equine Polysaccharide Storage Myopathy (EPSM). In EPSM there is a buildup of glycogen and abnormal polysaccharide in the skeletal muscles. Affected horses are not able to properly metabolize starches and sugars due to an abnormality of glycogen synthesis regulation that results in deposition and storage of unmetabolized carbohydrate in the muscles. The muscles are not able to use these abnormal polysaccharides for energy and suffer an energy deficit. Muscle fiber necrosis ensues as well as catabolism of muscle and a decrease in muscle fiber size. EPSM is believed to be an autosomal recessive trait. Mares appear to be affected more than geldings. The symptoms of EPSM include muscle weakness, especially following exercise, muscle wasting, muscle fasciculations, exercise intolerance, reluctance to exercise, intense sweating with exercise, and recumbency. Signs are often recognized in young horses when they begin training, but signs can develop at any age. Some horses show symptoms every time they are exercise, while others will have only a few episodes per year. Diagnosis is made based on blood work (increased muscle enzymes CK and AST), muscle biopsy, and now genetic testing using hair is available. There is no cure for EPSM, but many horses can be managed through dietary modification. The goal is to significantly reduce sugar and carbohydrate from the diet and replace them with fat. 20-25% of daily calories are supplied via fat. Grass hay should be fed. To see a complete EPSM diet, please see Dr. Beth Valentine’s recommendations at https://www.ruralheritage.com/vet_clinic/epsmdiet.htm. Exercise is also very important for these horses. They should have consistent daily exercise for best results. Rest is contraindicated for these horses unless they have had a severe bout of muscle weakness or muscle damage.

Azoturia/Tying Up/Rhabdomyolysis/Monday Morning Disease

Azoturia is the release of muscle breakdown products into the urine as a result of muscle damage. In draft horses, it is thought to be related to underlying EPSM. Muscle damage occurs with exercise and results in muscle pain, cramping, recumbency, and discolored urine. The symptoms are usually less severe than with EPSM and muscle enzyme (CK and AST) levels are increased less than with EPSM. Any draft horse that has an episode of azoturia should be tested for EPSM. Treatment consists of changing the diet to that recommended for EPSM and keeping your horse in consistent work.

Shivers

Shivers is a neuromuscular disease that affects the hind limbs of horses. It is most common in draft breeds. One or both hind limbs and the tail are affected. The symptoms include trembling of the hind when flexed, trembling of the tail when raised, difficulty backing up with the limb occasionally getting “stuck” in midair and trembling until it is gradually lowered, muscle atrophy, and difficulty picking up the hind feet to clean the hooves or to be shod. Most owners recognize that there is a problem with their horse when they try to work with the hind feet. Too often, horses are thought to be misbehaving when they will not easily pick up their hind feet. Punishing horses for this will only exacerbate the problem. Symptoms can worsen then the horse is excited or stressed. Patience is needed to work with these horses. In some cases, the disease progresses to the point that the hind feet can no longer be trimmed or shod. The cause of Shivers is still unknown. Although some horses suffer from both EPSM and Shivers, there is no definitive connection between the two diseases.

Chronic Progressive Lymphedema

Chronic Progressive Lymphedema (CPL) is a progressive swelling, hyperkeratosis, and fibrosis of the lower limbs. It is related to the syndrome in humans that causes elephantiasis. Shires, Clydesdales and Belgians are affected. This disease has also recently been found in a small number of Gypsy Vanners. There are ongoing studies to determine what, if any, genetic components are involved in the development of the disease. Currently researchers are investigating the genes that control elastin and vascular endothelial growth factor (VEGF). It is also thought that there is a hereditary component to the disease, so it is important not to breed affected animals. The disease can start at a very early age and, as the name implies, progresses throughout the life of the horse. It is usually first noticed as a mild case of pastern dermatitis (“scratches”) that does not respond to traditional therapy. When closely examined, thickened skin, often with thick skin folds and crusting lesions are present. It is imperative to clip away the heavy feathers on the horse’s lower leg to be able to adequately examine the limb, as well as to eventually treat the area. The thick feathers are suspected to play a role in the development of the disease. Over time, the lymphatic drainage system in the skin becomes inflamed and fibrosed and no longer functions properly. This, in turn, leads to lymphedema, fibrosis, decreased perfusion, a compromised immune system, and secondary skin infections. The lower limbs become grossly enlarged with thickened skin folds and nodules that affect mobility. The average age of the severely affected horse is 15 years. This makes screening for breeding purposes difficult. Severe infections can develop with non-healing oozing wounds. Many horses eventually have to be euthanized due to the severity of the disease. There is no cure for CPL. Symptomatic therapy includes clipping the feathers, keeping the limbs clean and dry, treating any mild symptoms aggressively, controlling infections and using compression bandages. Compression bandages have been shown to be of some benefit for some horses. These bandages must be applied correctly in order to be effective and not to injure the horse. Please have your TEVA veterinarian show you how to correctly place them.

Junctional Epidermolysis Bullosa

Junctional Epidermolysis Bullosa is a hereditary disease of Belgian Draft horses. This protein is necessary for the adhesion of the skin layers. Lack of this protein causes the skin to be very fragile and to rub off and blister at pressure points. In addition, there is formation of ulcers in the mouth and on the tongue, and sloughing of the hooves. Affected foals die within a few weeks of birth. Euthanasia if recommended as soon as a diagnosis is made due to the painful nature of this condition. There is a genetic test now to determine if a horse is a carrier of the mutated gene. The gene is a recessive trait, so it takes one copy from the dam and one from the sire to produce an affected foal. Known carriers should not be used as breeding animals.

Ocular Squamous Cell Carcinoma

Draft breeds are more susceptible to squamous cell carcinoma tumors of the eyelids and eye than other breeds.

Belgian Cataracts

Belgian Draft horses have a high incidence of cataracts.

Nutritional Needs

It is a common misconception that draft breeds need more grain due to their large size. The truth is that draft breeds have lower energy requirements than lighter breeds of horses, and therefore, require less grain on a per pound of body weight basis. Many owners feed based on the amount listed on the feedbag and are grossly overfeeding their horses. This can result in obesity and even laminitis. Less is often more for these horses. Since these horses are getting fed less than what the manufacturers recommend based on body weight, they are sometimes not getting the full amount of nutrients that they need. For horses on EPSM diets or for very easy keepers who do not get much or any grain, a good vitamin/mineral supplement and possibly a protein supplement is necessary. Ask your TEVA veterinarian what is needed for you horse to make sure that all of his nutritional needs are being met.

Draft horses are some of the most gentle, willing, and wonderful horses out there. It is important to know what medical concerns are specific to these breeds in order to care for them properly and to enjoy what they are willing to do for us.

Registered 2011 by Equestrian Collections
Author: Sallie S. Hyman, VMD, DACVIM, CVA

Information in this article is for educational purposes only and is not a substitute for evaluation by an equine professional. In particular, all horse owners should seek advice and treatment from a licensed veterinarian, such as TEVA, for their horses' medical care.

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