Muscular Diseases of the Equine Athlete: Myology, Myopathies

Exertional Rhabdomyolysis

Atrophy

Myositis

Denervation Atrophy

Direct Trauma

This occurs when the nerves of the muscle have been cut off and no longer fire synapses to the muscles. The muscle tissue does not have its own communication system and therefore, without the aid of nerves, it atrophies primarily at a cellular level. An example of this is sweeny, in which the infraspinatus and supraspinatus nerves are paralyzed and the muscles atrophy. This is apperant after a few weeks.

Direct trauma will cause damage and degeneration to the muscle tissue. This can be something severe, such as a tear of the tissue, or something as insignificant as a bruise. The muscle atrophies as a result of the loss of blood supply, hemorrhage, and torn tissue or a concurrent denervation.

When the muscle tissues are at their first stage of the healing process, Myositis can occur, generally due to an inflammation resulting from a predisposing factors other than trauma. To understand this reaction, you need to understand the inflammatory response of the muscle tissue.

Symptoms and Diagnosis

Treatments

Mild acute cases- include a limited amount of forced exercise such as walking. Treatment with analgesics, vitamin E, anti-inflammatories and selenium help a lot. Massage and warm, moist heat therapy have both also provided significant reduction in the inflammation within the muscles and a greatly reduced recovery time.

The most common symptom of this disorder is myoglobinuria, or coffee colored urine, it will usually occur when an animal is rested for a period of time during a training program, and then returned to hard work. Other symptoms include: stiffness in muscles, change in gait, elevation in respiratory rate and heart rate.

Severe acute cases- Treatment should be much more aggressive than that for the animal that is exhibiting a slight stiffness. Intravenous fluids should be administered immediately to re-establish the electrolyte balance. Analgesics can be administered, as well as corticosteroids, as they relax the sphincters of the capillaries. It can also be helpful to administer DMSO by a slow I.V. drip as it also has anti inflammatory properties.

Chronic cases- Treatments for this type are more challenging. Dantrium which is intracellular calcium clocking agent is one medication that is used, however it is expensive and there are questions about its effectiveness. Another medication, Phenytoin, has been successful in prevention of tying up in chronic cases.

When trying to diagnose this type of disorder, you must first rule out the following other issues that may appear similar to tying up. These include:

Colic, Laminitis, localized myositis, a disorder of the musculature of the back, or neurological disorders.

Diagnosis can be confirmed by blood testing to check the lebels of enzymes in the blood. If the enzymes are elevated (especially after exercise), and muscle biopsies may also be performed to confirm a diagnosis. The muscles of affecte horses will show lesions within the tissues and the fibers will appear swollen and be mixed with normal looking fibers.

Prevention

Ischemia

Lack of Use

Inflammation process of Muscle Tissue

The inflammatory reaction are the same as the clinical signs of myositis. The redness in the tissue is caused by an increased blood flow to the area and the pooling of blood within tissues, due to venous drainage. You can feel the heat from the affected area due to the increased blood flow to the muscle The swelling that occurs is a result of edema and the pain in the muscle tissues are caused by the chemicals that are released following the tissue injury and cell death.

This is often seen in association with a chronic lameness. This occurs because if a lameness is severe enough to cause pain, the horse will not use the limb normally, and consequential atrophy will occur from non-use.

When a horse has a history (more than one episode) a program of preventative measures should be taken. Supplemented feed with sodium bicarbonate and potassium chloride are effective for chronic cases as well as horses that are submitted to strenuous, hard workouts. A well balanced nutrition plan will also aid in preventing tying up.

Excessive Use

Bacterial Myositis-

1.) Immediately after a tissue is damaged, there is a brief constriction of blood vessels, that lasts just a few moments.

2.) Then the blood vessels will dilate to allow increased amounts of blood to flow to the injured muscles, where histamine, serotonin, and kinins are released.

3.) This then results in vasodilation and an increased permeability within the walls of the blood vessels. This reaction can cause components that are usually only in the blood stream to "leak out" into the surrounding tissues.

EX: Leukocytes (white blood cells) escape from the blood vessels into the tissue surrounding the injury. White blood cells are important in phagocytosis (the process where bacteria are engulfed and destroyed.)

4.) The dilation and leaking of components causes swelling within the tissues and cause edema. Pain is also found within this area because of the presence of toxic substances felt on the sensory nerve endings.

This is caused by streptococcal and closteridial bacteria. These organisms contaminate and invade the tissues following injury. They produce toxins which cause more tissue damage, swelling and ischemia.

Ischemia refers to the loss of blood supply due to a disruption with circulatory flow. Atrophy of the muscle will follow quickly afterward.

Viral Myositis-

The opposite of the former, This issue causes atrophy due to poor training and/or animal husbandry. If an animal is not properly nourished and trained, the muscle tissue will be broken down by the body as a source of protein. These animals often require a very long period of rehabilitation.

This type of myositis is rare, but occurs concurrently with viral respiratory infections. Irritating substances can produce a myositis within the horse. These include antibiotics, vitamin E, selenium and IM injections of Bute.

Diagnosis and Treatments

General signs of myositis include: Heat, pain, and swelling. Ultrasound can also be helpful in diagnosing the issue.

Treatments: include massage, acupuncture, acupressure, and warm moist heat help to reduce the inflammation and initiation of the healing process. Low level light therapy has also been shown to dramatically reduce the inflammatory reaction and accelerate healing. Additionally non-steroidal anti-inflammatory administration such as banamine or bute can also aid in relieving symptoms.

Muscular Diseases of the Equine Athlete: Myology, Myopathies and Myotherapies.

Myotherapies and Modalities

Modalities of Myotherapy

Benefits

Myotherapy

The benefits of massage are wide sweeping and if performed correctly, it is an art that can yield the following benefits:

1. Increased Blood flow to the tissues, allowing more nutrients to reach the cells and waste to be removed.

2. Increased lymphatic flow, which allows a reduction of swelling of tissues and aids in removing additional waste from the system.

3. Helps to releive muscle spasms by stretching and warming the muscle tissues by helping them to relax.

4. It helps to inhibit scar tissue or fibrosis.

5. It aids in pain relief by producing a natural analgesia due to the release of endorphins into the system.

1.) Massage- This is literally a communication between the fingertips and hands of the masseur and the muscles of the horse which tense and relax. With this digital contact the stress and pain can be removed from the tissues and a state of relaxation in sues. No other type of therapy can instill the stimulation and relaxation that hands on treatments will create. There are three types of massage therapy:

1.) Effeurage: the light pressure massage technique that uses the fingertips and thumb to apply gentle pressure. The practitioner can feel the musculature of the horse and find areas of issue. This is a good pre-event warm-up, or introductory effort before further therapies are administered.

2.) Petrissage: Best used in areas where stretching of muscle bundles would be beneficial. The fingers knead the muscles, allowing the body of the muscle to move bac.k and forth This is a powerful technique and, if not done properly, can be very painful.

3.) Friction: This is an intense therapy to a specific area. It is a deep sweeping motion of the digits which causes the muscle fibers to move back and forth rapidly. This causes adhesions and scar tissues within the muscle to breakdown. Do not abuse this technique as it could result in a damage of healthy tissues.

The treatment of the muscle tissue by any mechanical or physical means. It is a form of physical therapy. The goals of myotherapy are:

1.) To Reduce pain

2.) To restore range of motion to the affected area

3.) Restoration of the range of motion.

4.) Prevention of injuries.

5.) Enhancement of the performance levels of the animal.

Stretching and Manipulation

Additional types of Myotherapies

Acupressure/Acupuncture: This is a pressure that is applied to certain points of the body which results in changes of energy. This Chinese technique is over 3000 years old. These pressure points work like channels of the energy system within the body, and they can become blocked, Acupuncture/pressure helps to clear the pathways of the system so that the "Chi" or life force can flow smoothly through the body. Scientifically, these points on the anatomical body release endorphins and provide states of analgesia when pressure is applied to them. Blood flow to the area is also increased which allows filtration of the blood in the system.

Stretching is an act of passive movement by which a muscle and all of the connective tissues and structures are extended to their full lengths. It is usually performed after a massage session or during a warm up prior to a workout. It allows the muscles, tendons and ligaments to have greater elasticity and flexibility. The equine athlete is required to maneuver at great speeds and/or change direction rapidly. This increased flexibility gained from stretching allows for greater ease of the movements and this prevents serious injuries.

The most common reasons that you would stretch or manipulate a limb would be:

1. To alleviate pain. Areas of inflammation are relieved by stretching, by relieving small muscle spasms and reducing edema.

2. It helps increase flexibility. Stretching injured tissues help to prevent injury. This helps to increase the elasticity of the tissues and allows the muscle tissue to function fully.

Theraputic Lasers (L.L.L.T.): Laser stands for Light Amplification by Stimulated Emission of Radiation. It is a very effective treatment and it is also noninvasive and helps to increase lymphatic and blood flow, relieves pain (analgesia) and accelerates the wound healing, and has an antibacterial effect. This type of therapy should be utilized during the acute phase of the injury, and as frequently as possible.

Therapeutic Ultrasound: Sound waves are actually a deep tissue heating agent. They can heat specific structures such as muscles, tendons or ligaments and can be selectively heated without a corresponding elevation of skin temp. The benefits of this can be thermal, micro-massage from vibrations within the tissues, penetration of the tissues for applying heat, acoustical streaming, pain relief and softening of scar tissue.

Muscular Atrophy

Additional Types of Myotherapies

Heat therapy: A classic therapy, it aids the tissues in many ways, such as: Vasodialation, pain relief, and the increasing the tissue extensibility.

Cold Therapy: This therapy effects the tissues by also releaving pain, but it also controls swelling in the effected area by reducing blood flow and cause vasoconstriction. It also helps to control muscle spasms to the area.

Both of these therapies are tried and true ways of reducing the inflammatory response in the injured area, which greatly shortens the recovery time.

TENS (Transcutaneous Electrial Nerve Stimulators): Low level smooth currents provide stimulation to the nerves. High level frequencies are used to treat acute injuries and low levels are used to treat chronic issue. This is a "drug free" form of pain relief, as any pain impulses to the nerve are blocked with the pulsation of the machine.

Faradism: The Faridic electrical current is administered to the motor nerve of the muscle system. This imitates the natural rhythmic contractions of muscle tissue. This treatment simulates weightless exercise. It is a great concept when rehabilitation programs are started.

Atrophy- Wasting away of muscle tissue and/or the decrease in the size of the cell, tissues or organs.

Myology- Any inflammation of the muscle tissue that stems from a trauma or predisposing factor.

Myotherapy- Any treatment of the muscle tissue that is administered by physical or mechanical stimulation.

Atrophy is the shrinking of cell size of the muscles, as a result there is a reduction in muscle fiber and diameter. This atrophy can be localized, generalized or due to any oth the following factors:

1. Denervation

2. Trauma to tissues

3. Ischemia (restriction of blood flow)

4. Lack of use

5. Excessive use