Diagnosing Arthritis

Evaluating your horse for arthritis—and determining the extent of his condition

Question: My 12-year-old warmblood gelding has started to feel a bit stiff when he comes out of his stall. After a warm-up, he seems more his old self. I’m concerned that he may have developed arthritis, and I’ve scheduled the vet for a barn call. What will an examination likely include for a definitive diagnosis of the condition?

In an exam to diagnose the onset of arthritis, your vet will systematically flex each leg to temporarily accentuate any joint pain. © Amy K. Dragoo

Answer: Your veterinarian will perform several tests to determine whether your horse has arthritis, which, simply put, is inflammation in a joint. She’ll begin with a review of your gelding’s history. It will include questions about his age, use, activity level, previous injuries and particulars related to the onset of the stiffness you’ve recently noticed. Then she’ll use one or more of several techniques to evaluate the condition of the bones, cartilage, fluid and other structures that make up each joint.

Observation: Watching your gelding move will help your veterinarian identify lameness and begin to zero in on the affected limb. Be prepared for her to ask to see your gelding being led, ridden or longed. Working on a hard surface, at the trot and through turns, often reveals the most about irregularities in a horse’s way of going. He may bob his head or favor a leg that is painful.

Palpation: Your vet will run her hands over each leg to detect swelling (from fluid buildup), heat (from increased blood flow) and tenderness (from chemicals that stimulate nerve endings, making them more sensitive). She’ll also compare each leg to its pair to identify any differences that could indicate a problem.

Flexion tests: Your vet will continue to gather information by systematically flexing each leg to temporarily accentuate any joint pain. Your horse will stand square, on a firm surface, facing the direction in which he’ll trot off. The vet will then pick up a leg and hold it tightly flexed for a minute or so to stretch the joint capsule, increase pressure on bone and compress the surrounding soft tissues. Once the leg is released, your horse may take a few uneven steps or exhibit lameness for several minutes, depending on how painful it is for him to move.

Nerve blocks: Once your vet has identified the leg that’s affected, she’ll use nerve blocks to isolate the area that’s causing pain. This means temporarily and systematically numbing the sensory nerves that run down each leg and lie just under the skin. Note that sensory nerves are different from motor nerves, which send signals to muscles to move. Your vet will inject a numbing agent (usually lidocaine or mepivacaine) near the sensory nerves to selectively anesthetize a part of the leg. She’ll begin with the lowest areas in the hoof or leg and progress upward. After each nerve block, she’ll ask to see your horse move. The affected area will be revealed when your gelding shows a significant improvement in the lameness.

Additional evaluations: Your vet may recommend other procedures to gain more detailed information about your horse’s condition, though they aren’t absolutely necessary or financially feasible for diagnosing arthritis in every case. They include:

  • radiography (X-rays) to assess the condition of bones. Telling signs of arthritis that can be seen on X-rays include bone chips in a joint, the growth of new bone and a narrowing of the space between bones due to the breakdown of the cartilage that normally covers the bone ends.
  • ultrasound (high-frequency sound waves) to evaluate damage to soft tissue in and around the joints, including ligaments and tendons.
  • computed tomography to produce a detailed picture of the structure, shape and density of the bones in a joint. This is accomplished through multiple X-rays, taken at different angles across a limb, while a horse is anesthetized. A computer is then used to create images that show more detail than a regular X-ray.
  • nuclear scintigraphy to pinpoint inflammation. Radioactive dye, injected into the horse’s bloodstream, diffuses out of blood vessels and concentrates where inflammation is present. The dye gives off energy that is detected by a device called a gamma camera to produce a detailed image.
  • arthroscopy (examination with an endoscope inserted into a joint) to detect defects in cartilage.

Your veterinarian will use all of the information she’s collected to determine whether your horse has arthritis and, if so, the extent of the condition. “In the average horse, hock and coffin joint arthritis are the most common type, but we can see it in any joint,” says Moira Nusbaum, DVM, of PenMar Equine Practice in Myersville, Maryland. She adds, “Unless the arthritis is caused by a traumatic incident—a fracture in the joint or concussive injury, for example—it’s likely that multiple joints may be affected.”

Your veterinarian will make recommendations about how to proceed to keep your gelding comfortable and productive. She may prescribe rest, medication to reduce pain and inflammation and treatment to increase the viscosity of the joint fluid. She’ll also help you decide what level of activity will do your horse the most good. Many arthritic horses benefit from turnout and light riding as long as they are adequately warmed up before and cooled out after. A balanced diet will help your gelding maintain an appropriate weight, and regular farrier visits will minimize hoof and leg strain. In addition, certain supplements and treatments like massage, acupuncture and chiropractic may be useful for your horse.

Penmar Equine

Practical Horseman thanks Moira Nusbaum, DVM, for her technical assistance in the preparation of this article. A graduate of the Virginia–Maryland Regional College of Veterinary Medicine, in Blacksburg, Virginia, Dr. Nusbaum has owned and operated PenMar Equine Practice in Myersville, Maryland since 2011. There, she says, she “enjoys a nice mix of sport and pleasure horse work as well as some reproductive and foal work.”

This article originally appeared in the Spring 2021 issue.

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