Vet Vibes: Managing arthritis

VET VIBES

Managing arthritis

Unfortunately, arthritis can affect horses of all ages. RACHEL ROAN spoke to veterinarian Dr Calum Paltridge to learn more.

Arthritis can be a problem for horses at any age, so I asked Dr Calum Paltridge for a rundown on arthritis, what it involves, and the treatments available.

In a horse with arthritis, lameness is often the first noticeable symptom. “We get a lot of horses that just aren’t going right; they’re not travelling properly. They may not even be overtly lame but they’re not comfortable,” Calum explains. However, poor performance and discomfort can be caused by other problems, making it challenging to know if arthritis is the culprit or not. And that, Calum tells me, is why it’s important to investigate the issue thoroughly. In horses that develop arthritis, signs can include lameness, a reduced range of motion, heat in their joints, and swelling.

Arthritis may be the result of an autoimmune disorder, which is rarely reported, or down to osteochondritis dissecans (OCD), a developmental disease affecting the cartilage and bone in the joints causing fragments of bone to become loose. “While a lot of research has been conducted into OCD, vets still don’t really know what causes it or how to best prevent it. It’s likely to have a genetic and nutritional component behind it,” Calum suggests.

The most common type of arthritis is wear and tear osteoarthritis, often seen in performance horses. However, regardless of the cause, the impact is the same: lameness, pain and reduced performance. But can you still ride a horse with arthritis? That depends.

Arthritis can range all the way from very mild changes, which Calum believes will develop in most performance horses to some degree over their lifetime, up to the crippling arthritis most noticeable in aged horses that struggle in the colder months.

Diagnosis begins with a full lameness exam, including a trot up, nerve blocks, and flexion tests. However, X-rays or imaging are required for a definitive diagnosis, as tendon or ligament issues can also present in a way similar to

arthritis. While the use of MRI on horses is still uncommon in Australia, it’s a popular diagnostic tool overseas, with the highquality 3D imaging giving a much more comprehensive view of the problem. “A two-dimensional X-ray of complex structures such as joints will never give you the same quality of images as 3D scans, making diagnosis more difficult,” Calum says, adding that CT scans are a good option for imaging bones and not as expensive as MRI technology.

A common misconception is that arthritis is age related, but that’s not the case.

As a general rule of thumb, horses started younger tend to develop arthritis at a younger age. So does starting a horse before they fully mature have an impact on the development of arthritis, and does the type of work they do also play a role? "It's a really contentious topic," Calum comments. “Some research has shown that controlled exercise in horses, as young as even six months old, doesn't have negative effects, yet other studies have shown that it does. I think to some extent it benefits horses to wait for them to mature skeletally. Having said that, in a large cohort of young horses, some will go on to develop arthritis and some won’t. It’s not black and white.”

Although there’s uncertainty over whether riding a horse before it’s fully matured contributes to the onset of arthritis, Calum is of the opinion that the amount of work a horse has had, not necessarily the age, is a key factor. “A horse that develops arthritis at the age of six years, after two years of work, is no different to a horse that develops it at age 10 if they were started at eight years old.”

While a diagnosis of arthritis can be hard to hear, the outcome isn’t necessarily going to be negative. Depending on the joints affected and the severity of the arthritis when diagnosed, many treatments can lead to a good prognosis. While arthritic changes cannot be reversed, they can definitely be managed. “The prognosis for mild arthritis is usually pretty good, but it takes a fair bit of managing, and it is a degenerative disease,” Calum warns. The prognosis also depends on the horse’s discipline and level of physical stress; a 4* eventer is likely to have a different outcome to a trail riding horse. And while cold weather doesn’t cause actual arthritic changes, the symptoms often become more noticeable with horses taking longer to warm up.

The first line of treatment is an antiinflammatory such as bute. While anti-inflammatories don’t cure, they will alleviate symptoms to make the horse feel better. However, it does rule you out of competing. Compounds such as pentosan are aimed at assisting the health of the joint through improving the quality of joint fluid and the cartilage, thereby reducing arthritic symptoms and slowing down its effects. These compounds, Calum tells me, work systemically on the whole horse and every joint, making the horse more comfortable in their movement. As with any medication, they vary in their efficacy.

Calum notes that one of the biggest factors relating to a successful outcome is at what point owners start their horse’s treatment: “A lot of people don’t

FACING PAGE: The prognosis for arthritis can depend on the horse’s discipline and level of physical stress ABOVE: Arthritis is not restricted to older horses; it can be a problem at any age.

reach for a remedy until the horse is actually lame and having issues. They often expect miracles, but that’s just never going to happen.”

For riders who compete at higher grades, the best option is to start their horse on a joint supplement or treatment designed to help prevent wear and tear. “In my opinion, all horses are going to develop some degree of arthritis,” Calum says, “but by starting a horse on treatments when they begin work, you’ll get much more benefit than if you wait until they go lame. A lot of people don’t do it, but I think it’s a really good idea. It can also aid the recovery process. There’s no way to prevent arthritis but you can definitely slow its progression.” Cortisone is a relatively cheap and effective treatment that has been in use for some time with humans as well as horses, although how well it works depends on a variety of factors. Hyaluronic acid can increase the viscosity, or thickness, of the joint fluid, and it is often injected alongside cortisone.

In the last decade, biological therapy has become more prominent. In this approach, a small quantity of the horse's blood is taken and processed to produce the interleukin receptor antagonist protein, which modulates inflammatory responses. “Horses naturally produce this anti-inflammatory, but by processing it and injecting it back into the joint we’re providing it with a lot more than it would naturally produce,” Calum explains. While this treatment is one of the most effective, at nearly $3,000 per course it is also very expensive and is usually used once the horse has gone lame.

As with every aspect of caring for your equine partner, talking to your vet and equine nutritionist for help in developing a targeted approach to supporting your horse’s joint health will always beat waiting until they trot up lame.

Dr. Calum Paltridge (BVSc (Hons) MANZCVS) is the owner and veterinarian at Thunderbolt Equine Veterinary Services in Armidale, NSW.

ABOVE LEFT: X-ray of a very severely arthritic fetlock (Courtesy of Thunderbolt Equine Veterinary Services). ABOVE RIGHT: The most common type of arthritis is wear and tear osteoarthritis, often seen in performance horses.

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