Not All Lameness Is Osteoarthritis

Veterinarians evaluate each case of lameness for potential signs of osteoarthritis whether in young or old horses

In horses, it’s estimated that up to 60 percent of lameness cases are associated with osteoarthritis. Yet, not every equine lameness case signals the start of this progressive disease that doesn’t (yet) have a cure. Once equine osteoarthritis begins,there’s no cure available. However, owners can work with veterinarians to manage, and even slow, the process.

That’s why veterinarians evaluate each case in detail to determine its cause and outline treatments. Treatment options may be similar to dogs and cats, but the way the disease is expressed – especially in
performance horses that are asked to slide, stop or jump – may be dramatically different than in the family dog.

Osteoarthritis basics

Equine osteoarthritis (OA), also known as degenerative joint disease (DJD), begins as inflammation that may be due to a variety of factors, including joint instability or exposure to concussive forces, says Aimee Colbath, DVM, and post-doctoral fellow at Colorado State University Equine Orthopaedic Research Center.

“The horse’s conformation can dictate predisposition to equine osteoarthritis,” Colbath says. “Although some activities in Western performance horses can affect joints more than others. For instance, the sliding stop or cutting horses crouching down. The horses that do this work are often Quarter horses, but that doesn’t mean the breed itself is predisposed to the disease.”

Whether due to conformation or work, all osteoarthritis begins as inflammation that slowly breaks down cartilage. Cartilage is important to helping bones glide as they move the body. The inflammation breaks down this cartilage, which then leads to erosion of this important buffer. Sometimes, it can even lead to exposed bone.

“The horse’s body tries to stabilize the area, which leads to new bone growth,” Colbath says. “This can actually fuse joints together in some cases.”

This process can be painful for the horse, which often leads to signs of lameness. A veterinarian is required to determine the source of the lameness.

“Lameness can be a result of a soft tissue injury, ligament straining – like we would sprain an ankle or joint,” Colbath says. “OA is common, but it’s not the only cause.”

Lameness may not even be the first sign of the osteoarthritis, says Stacey Buzzell, DVM.

“It can start as something as simple as not being willing to move forward off the leg or not being as playful in the field,” she says. “Owners might notice a change in demeanor or attitude – being less happy or more reluctant to work for you. Then, as things progress, that will lead to signs of lameness.”

Owners and trainers must be in tune with the individual horse to know what their “normal” attitude and function is, Buzzell says.

Treatment

Once equine osteoarthritis begins, there’s no cure available. However, owners can work with veterinarians to manage, and even slow, the process. There are a range of tools veterinarians can choose from depending on the horse’s specific case.

Anti-inflammatory drugs: The best bet veterinarians have at their disposal today is to stop the cycle of inflammation with anti-inflammatory drugs. These drugs can also help manage pain associated with the disease.

Interleukin-1 Receptor Antagonist Protein (IRAP): This helps counteract the cytokines including IL-1 that can lead to further damage due to the cycle of inflammation and joint damage.

Intra-articular medications: Hyaluronic acid or polysulfated glycosaminoglycans can help improve the quality of the joint fluid at the inflamed joint and promote the gliding action that the disease diminishes.

Management: Sometimes, corrective shoeing can help change the horse’s conformation enough to remove stress on the affected joint. Keeping the horse moving also can help support continued joint function and maintain a healthy weight, which helps put less pressure on the joints.

“We recommend a longer period of warming up and cooling down for affected horses,” Colbath says. “Warm up may take a bit longer for these horses than it used to, but continued movement can help support healthy joint function.”

Prevention

There are several supplements that claim to help prevent the development of equine osteoarthritis, but it can be difficult to determine what will work for a specific horse, Colbath says.

On the other hand, there’s no penalty for using a supplement. Colbath recommends looking for products with veterinarian support, which often have better quality control than others.

While there are few studies looking at joint supplements as an OA preventive, the major ingredients include singularly or combinations of glucosamine, chondroitin sulfate or avocado/soybean unsaponifiables (ASU).

“Reducing inflammation can help slow the process that may be occurring,” Buzzell says. “It’s never too early to start a horse on a supplement. It’s a product that can be maintained throughout the horse’s lifetime to help maintain joint health.”

Veterinarians and horse owners are constantly working against osteoarthritis, she says. Anything in the arsenal that can prevent or help slow the disease helps horses have higher quality, longer lives.