Equine Lameness Series: All About Joint Injections

Intra-articular injections, more commonly referred to as joint injections, are one of the most commonly performed procedures on equine athletes. In years past, joint injections received a bad reputation. This was largely a result of misuse and using lower quality medications in the injections, which gave subpar results. Research has proven that joint injections, if done appropriately, are a benefit to the equine athlete and can actually help to heal the joint rather than tear down the cartilage.

Joints are most commonly injected with a combination of hyaluronic acid (HA), a corticosteroid, and a small amount of antibiotic. However, there are different levels of injections that are available to tailor to each horse’s discipline and each owner’s budget.

• Corticosteroid: Using steroid alone is the simplest level of joint injection offered. This helps to quiet down inflammation within the joint and increase comfort for the horse. Peak effect is typically achieved around 10 days post-injection.

• Hyaluronic acid: Adding HA to a steroid injection is the next step up. In healthy joints, HA acts as lubricating molecules that promote smooth, frictionless motion. It also helps mitigate the action of inflammatory mediators within the joint and protects joint cartilage from degeneration. There are also different classes of HA, and at SPVS we use the highest quality with the highest molecular weight. This is important as the higher molecular weight products don’t diffuse across the joint capsule as easily as lower molecular weight products. This means the HA molecules keep the steroid centralized within the joint longer, which in turn enhances the healing process.

• Antibiotic: All our joint injections include a small amount of an antibiotic to help minimize any joint infection.

• Biologics: These are the current “gold standard” of joint injections. For biologics, we extract living organisms from the horse’s own blood and inject them directly back into the joint. By putting the horse’s own healing factors back into the joint, we are achieving an amplified healing effect. There are many biologic products on the market, including Prostride, IRAP, PRP, RenoVo, and more. At SPVS we are now offering Prostride!

Before we are able to inject joints, we need to determine which joints require treatment. This starts with our comprehensive lameness exam, as we discussed in our previous blog post. If more localization of the lameness is needed after the exam, we can narrow it down further with nerve blocks. With nerve blocks we can numb areas of the limb in a stepwise fashion to see if the horse becomes sound again. We can also try to localize the source of the lameness with diagnostics such as radiographs or ultrasound. Once we have identified the source and determined whether the issue would benefit from injections we can proceed with treatment.

Because we are entering into a joint when performing injections, a sterile prep of the site is absolutely necessary to minimize risk of infection. We also use a small amount of antibiotic in our joint injections to help minimize infection. Using antibiotic in joint injections has been a debated topic among equine veterinarians in the past, as it has been shown to have some negative effect on cartilage. However, many veterinarians believe that the benefit of protecting against joint infection outweighs the risk, especially if using very small amounts like we do.

After joint injections, we prefer the patient to rest for at least 3 days, but 5-7 days is most ideal. Then they may return to work. We recommend doing a follow-up lameness exam 4-6 weeks after injections to monitor response to treatment and make sure the patient is 100% sound. Occasionally we find that the injections treated a large source of discomfort and once that is treated there is another issue that was being masked by the joint pain. At SPVS, we offer our follow-up lameness exams for free after performing joint injections.

Interested in learning more? Follow along in future newsletters for our continuing series on equine lameness!

The article “Equine Lameness Series: All About Joint Injections” first appeared in our Summer 2023 Newsletter.