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Equine Arthritis, A Pain in the JointBy Kentucky Equine Research Staff · November 2, 2002

Simply stated, arthritis is inflammation in a joint. Sudden severe joint inflammation with pain, heat, and stiffness is referred to as acute arthritis. Long-term joint inflammation is termed chronic arthritis. Osteoarthritis refers to a condition that involves progressive degeneration of the joint cartilage, enlargement of the bone margins, and changes in the membrane surrounding the joint capsule. This condition is more common in older individuals, and is marked by pain and stiffness associated with activity. Rheumatoid arthritis, an autoimmune condition in humans, does not seem to be a problem in equines.

What causes arthritis?

Acute arthritis can be caused by injury or by bacterial or viral infection. Chronic arthritis is often osteoarthritis that results from the cumulative effects of day-to-day activity and stress. Old injuries, joint infections, and years of training and performance can all lead to the development of joint pain and stiffness. Poor conformation, hoof deformities, and problems with trimming or shoeing are other contributing factors. Probably there is some genetic influence also.

The chronic type of arthritis is what most horse owners think of when they see older horses that move stiffly: “How's old Blaze getting along?” “Oh, he's kind of slow getting up after he lies down, and he's definitely ‘off' when he moves around; guess he's got some arthritis. He's 24, you know, but I still ride him a little bit, and he can throw in some pretty good bucks on a cold, windy morning.”

How is arthritis diagnosed?

While arthritis is quite common in older horses, it can occur well before what we think of as old age. It is important to identify the cause of any stiffness or lameness regardless of the age of the horse because early treatment can often allow the horse to continue a productive, comfortable career. Prompt attention to minor lameness or injury also helps to minimize unsoundness as the horse ages.

After taking a history of the problem, a veterinarian can continue the diagnostic process by using one or more of an array of techniques to gain information about the condition of the bones, cartilage, and fluid that make up a particular joint. An examination for lameness may be quite involved, but the process is necessary in order for a practitioner to pinpoint and treat one or more conditions while eliminating other possibilities.

• Watching the horse move is the usual first step in diagnosis. The horse may be ridden, longed, or led. Mild lameness is often most easily seen when the horse is trotting, working on a hard surface, or moving through a turn.

• A hands-on physical examination can detect swelling, heat, and tenderness. Comparing the affected limb to its normal mate helps to point out any variations that may indicate a problem in a certain area.

• A flexion test is useful in determining which joints are stiff or painful. The veterinarian holds the horse's leg tightly flexed for a minute or so, after which the horse is immediately trotted on a firm surface. Subtle lameness often becomes more visible after this procedure.

• Once a particular leg is identified, nerve blocks can be performed to isolate the affected joint. The veterinarian begins by anesthetizing the lowest joints in the hoof or leg and progressing upward until the lameness disappears. When the horse moves sound, suspicion falls on the most recently blocked joint.

• Radiography, nuclear scintigraphy, arthroscopy, synovial fluid analysis, and ultrasound can reveal detailed information about the condition of the bone, cartilage, and joint capsule. These procedures are helpful in making an exact diagnosis and directing the course of treatment, but may not be necessary or financially feasible in every case.

What is involved in treatment?

Early treatment is extremely important and often has excellent results. Many cases of joint pain and inflammation can be successfully treated with a combination of rest and medication. The veterinarian may choose from among nonsteroidal anti-inflammatory drugs (bute and Banamine) to reduce pain and inflammation; MSM, a sulfur derivative with anti-inflammatory properties; or injectable products like hyaluronic acid or polysulfated glycosaminoglycans to increase viscosity of joint fluid and inhibit cartilage degeneration. Many horse owners have testified to the effectiveness of products containing glucosamine and chondroitin. Treatments like massage, acupuncture, and chiropractic have also provided relief to some horses. The limited research conducted on some products and treatments has failed to yield firm guidelines for their effectiveness or use. A veterinarian's assessment and recommendations should be the guide for treatment of an arthritic horse.

What management practices can help a horse with arthritis?

Common sense dictates some steps that can help an arthritic horse stay comfortable. Prompt veterinary care of minor lameness can sometimes minimize joint ailments in the horse's later years. While hard work may be beyond the capability of horses with chronic arthritis, stall rest often makes the problem worse. Horses that are turned out with a small group of pasture mates will move around enough to eliminate some stiffness. Many arthritic horses benefit from light riding or driving on a regular basis if owners allow time for gradual warmup and cooldown periods.

Providing balanced nutrition is important, as is keeping the horse from becoming overweight, and regular farrier visits are imperative to minimize strain to the legs and feet.

Are new treatments being developed?

Several promising arthritis treatments are on the horizon. Scientists are presently looking into:

• Ways to interrupt the actions of chemicals released by diseased joints. These substances cause inflammation and prevent repair of cartilage.

• Blood analysis that will detect the earliest signs of joint degeneration, allowing treatment to begin before damage progresses.

• A method of “resurfacing” joint cartilage with harvested or laboratory-grown tissue.

• Engineering gene sequences that can be injected into injured joints to prevent the development of osteoarthritis. Some of these techniques have been developed in humans or other animals and are being adapted for equine application. These waves of the future hold the promise of extending a horse's years of comfort and use.