by Casie Bazay

The ins and outs of arthritis in horses

The ins and outs of arthritis in horses

Arthritis is one of the most common conditions affecting both performance and pleasure horses. In fact, it is believed to account for up to 60% of all cases of equine lameness. Surprisingly, this condition doesn’t just affect older horses, but horses of nearly any age. 

How healthy horse joints function

To understand how arthritis affects a horse, it’s important to first understand the anatomy and function of healthy equine joints. Put simply, a joint is where two or more bones meet in the body, allowing for movement. Horses have three different types of joints: 

  1. Synovial joints: Accounting for most of the joints in the horse’s body, synovial joints allow for different degrees of movement. For example, hinge joints like the horse knee, fetlock, and hock allow for mainly flexion and extension, while ball and socket joints like the hip and shoulder allow for a broader degree of movement and rotation.

  2. Fibrous joints: Less common than synovial joints, fibrous joints do not allow for movement between bones. An example would be the bones in the horse’s skull. 

  3. Cartilaginous joints: Occurring where bones are connected by cartilage, these joints allow limited movement and provide shock absorption. The joints between the vertebrae in the horse’s spine are an example of cartilaginous joints. 

How does arthritis occur?

Technically known as osteoarthritis (OA), but more commonly referred to as arthritis, this condition is characterized by chronic, painful, and often progressively worsening degeneration of the articular cartilage that covers the ends of the long bones inside a joint. However, arthritis also affects the underlying bone and soft tissues. 

Arthritis can occur in both synovial and cartilaginous joints but more commonly occurs in the synovial joints of the horse’s leg, especially the hocks, knees (carpii), stifles, and fetlocks. Less commonly, horses can develop arthritis along the spine, in the hips, or even in the jaw at the level of the temporomandibular joint. 

Osteoarthritis in horses often develops after there has been some sort of interference with the normal structure and/or function of a joint. This could occur from trauma, infection, overuse, or even day to day “wear and tear.” The result is inflammation, swelling of the joint, pain, and restricted movement. As the condition progresses, new bone is formed in response to the surface damage. However, the new bone is rougher in texture and is not protected by cartilage. 

It is also important to note that poor nutrition practices which lead to total body inflammation can be a major cause of arthritis in horses. 

Dr. Rob Franklin, FullBucket co-founder and equine veterinarian, explains, “I first became aware of the prevalence of nutritionally induced inflammation and arthritis when I became a concierge vet for a halter horse barn. These horses ate MASSIVE amounts of grain, were exercised very little (i.e. No wear and tear, trauma or overuse) and had severe arthritis developing along with laminitis. Controlling body inflammation by managing the diet may be the most important thing a horse owner or trainer can do to mitigate or minimize arthritis.”

The bad news about arthritis is that it’s irreversible. In other words, it cannot be cured. However, the good news is that there are ways to reduce the inflammation and manage pain and further damage with specific practices promoting joint care for horses. This will be discussed more in an upcoming article on various horse arthritis treatments.

Symptoms of equine arthritis

The most common signs of arthritis in horses include:

  • Heat
  • Swelling (due to excess joint fluid)
  • Lameness
  • Stiffness
  • Deformation of joints, and 
  • Crepitus (popping or crackling sounds produced by a joint). 

Other symptoms of arthritis may be more subtle. For example, your horse may experience a gradual decrease in performance or show a reluctance to turn in one direction. His gaits may also feel off or “choppy”. He may be stiff when first warming up and then gradually loosen up. For older horses where multiple joints may be affected, arthritis may also show as a difficulty getting up after a period of laying down.

It’s also important to note that an acute form of arthritis known as septic arthritis involves severe inflammation, pain, and lameness. This is caused by an infection and if it is not quickly treated, septic arthritis can lead to severe destruction of joint surfaces which may end a horse’s career or even necessitate euthanasia if the horse is in too much pain. Septic arthritis is usually caused by an injury such as a puncture wound near a joint. However, it can also be carried by the bloodstream if there is an infection elsewhere in the body, though this occurs primarily in patients with heart valve infections or neonatal foals. 

Which horses are most at risk for developing arthritis? 

As stated before, any horse can develop arthritis and nearly all horses do if they live to a certain age, but horses regularly participating in some of the more strenuous disciplines are automatically at higher risk. 

The following factors also put a horse at higher than normal risk for developing early onset arthritis:

  • Obesity, as extra weight puts added stress on the joints and creates inflammation throughout the body;
  • Overfeeding grain and other poor nutritional practices, such as not controlling proper Omega-3 fatty acid ratios;
  • Sustaining a bone or soft tissue injury, as any sudden, massive incidence of inflammation can damage cartilage and set the stage for the development of arthritis;
  • High intensity training before physical maturity, as a young horse’s cartilage cannot withstand hard or repetitive work and can be damaged, leading to early development of arthritis;
  • Poor or inconsistent hoof care that allows for overgrown or improperly trimmed/shod hooves and puts added stress on nearly all of the joints of the horse’s body; and
  • Overuse: if horses are worked hard with little to no layoff time, this increases stress on the joints and doesn’t allow time for the body to deal with existing inflammation.

Dr. Franklin reminds us that “Obesity more often results in inflammation in the body and therefore the joints versus simply overloading the joints. In my opinion, keeping your horse at a healthy weight with a focus on an anti-inflammatory diet is the most important management factor in arthritis. ”

Diagnosing equine osteoarthritis

If you suspect that your horse might have arthritis, the first thing to do is have a full veterinary exam. Your veterinarian will palpate the limbs, looking for evidence of swelling, and will likely do flexion tests, testing for range of motion in the leg joints. They will likely want to see the horse move as you walk or trot him in hand or they may ask to see the horse ridden or lunged. 

However, because some signs of arthritis are subtle, your veterinarian may not be able to make the diagnosis by clinical examination alone. A nerve block exam may be necessary as well, in which your vet will inject a local anesthetic around specific nerves in order to confirm the site of pain. Radiographs (x-rays) are used to rule out fractures and to also examine bone surfaces of the affected joint for signs of damage or arthritis. If there is evidence of injury, degeneration, or abnormality, it could be a telltale sign of arthritis. 

Magnetic Resonance Imaging (MRI) and Computed Tomography (CT or CAT Scan) can also be used to diagnose cartilage or other soft tissue injuries including tendon, ligament problems and arthritis. In complex cases, nuclear bone scans can be used to image specific areas of increased bone metabolism. This is a more detailed procedure, requiring injection of a radioactive bone tracer and specialized imaging equipment. 

However, once a diagnosis of arthritis has been made, your veterinarian can suggest possible treatment options, including dietary changes, horse arthritis supplements and pharmaceutical agents to control pain, inflammation and joint mobility. We will discuss many of these options in a follow-up article. 

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