Joint injections for your horse

As horses age, initiate training programs, and go about their lives and jobs, their joints experience wear-and-tear. Joint disease is a common problem that may result in general discomfort, or even performance-limiting lameness in equine athletes. Osteoarthritis in horses is characterized by chronic inflammation, which results in progressive, non-reversible deterioration of the cartilage that lines joints, and remodeling of the bone underlying the cartilage. This can lead to narrowing of the joint space, and formation of “bone spurs” which can result in reduced joint function. Diagnosis of osteoarthritis is routinely based on lameness examination and diagnostic imaging (ultrasound, x-rays, etc.). There are many commercially available medications that can provide osteoarthritis relief by way of their symptom-modifying, or disease-modifying effects. Some of these medications are administered systemically (Zycosan, Adequan, Legend, Equioxx, Phenylbutazone, etc.). Intra-articular therapies (i.e. joint injections) are those that are administered directly into the affected joint(s) for targeted treatment, and reduction of systemic side-effects.

 

Options for intra-articular injections (medications that go into the joint):

  • Corticosteroids

    • Corticosteroids are an effective first line approach at combating joint disease, They are effective and generally more inexpensive than other options. There is some evidence to show that repeated use can have adverse effects on cartilage. Corticosteroid administration is a possible risk factor for laminitis, so should be avoided in horses with metabolic disorders including Equine Metabolic Syndrome (EMS), and Pituitary Pars Intermedia Dysfunction (PPID, formerly equine Cushing’s).

  • +/- Hyaluronic Acid (HA)

    • Hyaluronic acid is a substance naturally occurring in synovial fluid and cartilage lining joints. The concentration of hyaluronic acid decreases with joint inflammation which makes the joint fluid less viscous. Injections including hyaluronic acid can help increase the viscosity of synovial fluid. Hyaluronic acid may be combined with corticosteroids for increased efficacy.

  • Orthobiologics 

    • IRAP
      • Interleuken-1 receptor antagonist protein (IRAP) is a product derived from the horse’s own blood, drawn on site and incubated for 22-24 hours. IRAP is an anti-inflammatory product that blocks the action of interleukin-1, a major driver of joint degradation and pain. Intraarticular treatment with IRAP is generally administered as a loading series of three injections, one week apart. After the loading series is complete, a single injection may be performed on an as-needed basis. Additional doses of IRAP can be frozen and stored for later use.
    • Pro-Stride/APS
      • Autologous protein solution (commonly known as Pro-Stride) concentrates anti-inflammatory proteins as well as growth factors, derived from the horse’s own blood. It is a next-generation joint therapy that essentially combines the healing properties of PRP with the powerful anti-inflammatory proteins like IRAP. Pro-Stride can be drawn on site and processed in approximately 20 minutes for immediate use. Pro-Stride requires a single injection that delivers both regenerative and anti-inflammatory benefits. Similar to the other orthobiologics, Pro-Stride is safe for geriatric or metabolic horses.
    • PRP
      • Platelet Rich Plasma (PRP) concentrates platelets from the blood that produce growth factors. It is the original biologic product, and still occasionally used for intraarticular injection, though it is now more frequently used for tendon and ligament injuries to “fill in” defects and allow the body a scaffold over which to heal.
    • Alpha-2 Macroglobulin (A2M/Alpha-2 EQ)
      • A2M is one of the newest orthobiologic therapies for joint disease. The processing concentrates a large protein that counteracts destructive enzymes that cause cartilage degradation, in addition to reducing inflammatory cytokines. A2M can be processed stall-side for immediate use, and also has the benefit of being able to be frozen for future use as well.
    • Mesenchymal Stem Cells (MSC)
      • Stem cell therapy involves collecting stem cells from a horse’s own body, usually from fat or bone marrow, and processing the cells in a specialized lab. Once prepared, the cells are injected directly into the injured area (into joints, or soft tissue), where they can stimulate tissue repair and reduce inflammation.

  • Polyacrylamide Gels

    • Arthramid (2.5% polyacrylamide hydrogel)
      • The polyacrylamide gels act as synthetic joint lubricants. They provide a similar benefit to hyaluronic acid, but persist in the joint for a longer period of time. Arthramid incorporates into the joint capsule itself, and promotes elasticity and strength of the synovial lining. Over a two-week period, the gel becomes integrated into the synovial lining and surrounding tissue of the inner joint capsule to form a thick, cushion-like membrane.
    • Noltrex (4% polyacrylamide hydrogel)
      • While Noltrex and Arthamid are similar, Noltrex has a propensity for aggregation on the cartilage in joints. Noltrex substitutes for the lack of lubricating properties of joint fluid in compromised joints to reduce friction and provide physical protection to the cartilage.

Aftercare

After joint injections, some period of rest is indicated. Generally, stall rest is recommended the remainder of the day of injection, followed by a period of no forced exercise, then gradual return to athletic performance. Joint injections are frequently repeated every 6-18 months, depending on severity of the disease in the affected joint(s). While the risks of complications from joint injections are low, a local inflammatory response called a “flare” can result in the acute post-injection period. Joint infections are the most serious consequence to injection, and require prompt and aggressive treatment. Aseptic technique is paramount when performing joint injections, so these should only be performed by a licensed veterinarian.

It is always best to consult with your veterinarian when developing a treatment plan for your horse and unique situation. Oftentimes, a multifaceted approach to treating lameness is best, and promotes long-term joint health. A lameness evaluation with a veterinarian is the first step in devising a comprehensive treatment plan.