Recently introduced to veterinary medicine, extra-corporeal shock wave therapy (ESWT) eases the discomfort of many joint, back, muscle and tendon problems.

Chronic pain can be debilitating and draining. What you may not know is that it’s a learned pain, and an illness in itself.

For example, consider a dog with shoulder pain. When he puts his weight on the sore leg, he develops a protective posture. In other words, the shoulder muscles contract to protect the leg from impact, thereby creating a limp. This contraction also leads to a reduction in blood fl ow to the area, a decrease in proper muscle function, and a buildup of lactic acid and other chemicals that maintain inflammation. If the pain is persistent, it becomes stored in the brain and at that point becomes a chronic illness, a memory engram. Every time the muscle contracts, the brain thinks there’s going to be pain, and that perpetuates it and makes it chronic. The pain switch is always in the “on” position because the initial (acute) painful event was not remedied.

Conventional treatments for chronic pain include non-steroidal anti-inflammatories and non-opioid drugs, but what happens when the pain can no longer be successfully or safely treated with these chemicals? Recent research and advances in veterinary physiotherapy have opened doors on many new ways to help reduce or eliminate chronic pain. These include massage therapy, therapeutic exercises, acupuncture, lasers, ultrasound, TENS therapy, hyperthermia, nutraceuticals, support devices like braces and wheelchairs – and more recently, extra-corporeal shock wave therapy or ESWT.

ESWT explained

ESWT is used in human medicine for the breakdown and disintegration of kidney stones. But it has some interesting side effects – it reduces pain and stimulates healing in areas of the body not related to the kidney stones. In other words, people with sore backs were no longer feeling their back pain. Hence, ESWT can be an effective way to deal with chronic pain in companion animals.

ESWT is administered via shock waves generated within a handheld unit placed on the affected area. The animal’s hair is first shaved, and a gel is applied to the skin to conduct the pressure waves.

There are two types of ESWT units

1. Focused shock wave devices deliver waves deeply into the tissues. However, this deep penetration can be painful and usually requires sedation or analgesia in order for the treatment to be performed.

2. Radial shock wave units create a wave of pressure closer to the skin’s surface; this is less painful and can be used without sedation to treat joints and tendons. The radial head can be pressed more firmly on the area, sending the waves deeper into the tissue; or backed off to lessen the wave’s intensity if the animal finds it too uncomfortable. Shock waves provide analgesic effects via a number of mechanisms. ESWT causes hyper-stimulation of the nerves that send pain to the brain, thus blocking the nerve pain impulse according to the gate-control theory. ESWT distorts the cell membranes so the pain receptors cannot build up a pain firing potential. It causes a buildup of free radicals in the area, which stimulates the release of chemicals to inhibit pain. ESWT also allows for new blood vessels to grow in the tissue, which helps remove inflammatory chemicals and debris and allows proper nutrients to reach the area. In chronic conditions, the tissue is more fibrotic and ESWT helps to remove the scarring. It can also improve muscle rigidity and spasticity through all the above healing mechanisms.

What are the contraindications?

There are some situations in which ESWT should not be used:

• Immediately after surgery. ESWT should be used only after eight weeks of healing have occurred following any joint surgery.

• When metal implants are used in knee operations; ESWT should not be used directly over these implants.

• If the injury is acute; ESWT is meant only for chronic conditions.

• If there’s a tumor in the treatment area, whether on the skin, within the muscle or in the bone.

• When a young animal is still growing.

• If the animal has a bleeding disorder or
there’s an infection in the area.

What can you expect from a treatment?

ESWT can be used for joint conditions in the hip, knee or elbow, and for tendinopathies in the shoulder. It can also be used for back soreness, muscle pain and bursitis. It’s important to know, however, that every case has to be individually evaluated for ESWT by a veterinarian knowledgeable in this type of therapy.

ESWT treatments are usually given every two weeks for a total of three. Possible side effects include some bruising and swelling, and a temporary worsening of the condition that usually subsides in two days. Be patient. It can take several weeks for ESWT to take full effect, and up to a month after treatments have finished for pain relief to be noticed. Sessions can be repeated after a month following final treatment to increase the benefits and maintain a pain-free or reduced pain status.

Any pain medication should be withheld for two days before ESWT treatment is applied to the body. Because we are dealing with a chronic condition, adjuvant therapies such as massage are also recommended.

Given the detrimental effects of conventional pain medications when used long-term, the addition of extra-corporeal shockwave therapy to the list of alternative treatments for chronic pain is a definite advantage.