Corticosteroids are a class of medication used to treat inflammation and pain. Corticosteroid joint injections are a common treatment for arthritis in horses.

When injected directly into a joint, corticosteroids produce an anti-inflammatory effect, reducing pain associated with arthritis and slowing damage to joint cartilage. [1] These injections can improve soundness, allowing horses with arthritis to continue performance and prolong their career. [1]

Equine veterinarians can inject corticosteroids into any accessible joint space, such as the hocks, fetlocks, knees, pasterns, hips, and neck.

Corticosteroid injections are safe for horses when performed by a veterinarian using appropriate precautions to prevent joint infections and other side effects.

Corticosteroid Injections in Horses

Corticosteroids are a group of steroid hormones naturally produced by the horse’s adrenal gland. [1] These hormones have a variety of effects within the body, including regulating cellular metabolism and reducing inflammation. [1]

Because corticosteroids have anti-inflammatory effects, they are used to treat inflammatory diseases in horses by injection into specific locations. [1] Administering corticosteroids directly into affected tissue interrupts inflammatory pathways, reducing pain and swelling. [1]

Clinical Use

Corticosteroids are primarily used for treating arthritis in horses. Pain from arthritis is linked to inflammation and degeneration of the joint cartilage, smooth tissue that covers the ends of bones in joints and facilitates movement and shock absorption. [1]

Horses may develop arthritis for several reasons, including infections, previous injuries, overuse of a joint, and normal degeneration of the tissues due to aging. [1] All of these factors can cause irritation and inflammation within the joint, triggering release of enzymes (proteins that break down tissue) that destroy joint cartilage. [1]

As the joint cartilage is depleted, the bones that make up the joint come into contact with each other, causing severe pain and lameness. [1] The inflammatory response within the joint also activates nerve endings surrounding the joint, further intensifying pain in the affected area. [1]

Arthritis is a progressive disease with no cure, as current medical treatments cannot entirely repair cartilage damage. [1] Over time, changes in the bone and thickening of the joint capsule from inflammation result in decreased range of motion and chronic lameness. [1]

Corticosteroids counteract the inflammation present in arthritis, slowing the progression of cartilage damage and reducing pain. [1]

Types of Corticosteroids

Veterinarians may use one of several different corticosteroids for treating joint inflammation, or a combination of steroids. [2]

Although all types of corticosteroids can successfully treat joint inflammation, evidence suggests certain corticosteroids may be more beneficial to specific joints. [4]

Commonly used corticosteroid joint injections for horses include: [1][3]

Type of Corticosteroid Duration of Action Typical Use
Betamethasone acetate Medium to long Both high and low motion joints
Isoflupredone acetate Short to medium Both high and low motion joints
Methylprednisolone acetate Long Low-motion joints
Triamcinolone acetonide Medium High-motion joints

 

The choice of corticosteroid primarily depends on the joint being treated and the prescribing veterinarian’s clinical opinion and experience. [3][4]

High Motion Joints

Certain steroids are more chondroprotective (protective of cartilage tissues), which makes them more suitable for high motion joints. High motion joints, such as the stifle and fetlock, move through a wide range of motion during normal movement of the horse. [4]

Cartilage is particularly important in these joints to as it facilitates smooth movement and reduces bone-on-bone contact. Chondroprotective steroids help maintain cartilage health, supporting comfort and mobility in the horse.

The most commonly chosen steroid is triamcinolone acetate (TA), in part because it does not damage cartilage or joint capsule cells. [1][3] TA may also improve the quality of joint fluid, promoting a healthier joint environment. [1]

Low Motion Joints

Some steroids are preferred for use in low motion joints in the horse, such as the pastern or lower hock joints. [4] While these joints do not move significantly during normal motion, even small movements can cause pain and lameness when the joint is affected by arthritis.

The goal in treating low motion joints affected by arthritis is to achieve ankylosis (joint fusion) and stop all movement within the joint. [5] This prevents painful bone-on-bone grinding when the horse moves, resolving lameness.

Corticosteroid injections that can damage cartilage cells may increase the rate of ankylosis while also promoting reduced inflammation and pain relief. [5]

The most common steroid used in low motion joints is methylprednisolone acetate (MPA). [3] MPA decreases production of proteoglycan, a major component of joint cartilage. [1] MPA may also destroy cartilage cells and cells in the joint capsule, furthering joint damage and promoting ankylosis. [1]

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Effects on Tissues

Corticosteroids exert an anti-inflammatory effect by interrupting the pathway that triggers inflammation in response to cell damage. [1] As a result, corticosteroids decrease pain signaling, leading to increased comfort for the horse. [1]

Injecting corticosteroids directly into a joint allows for administration of a higher concentration of medication to the desired area compared to systemic (whole body) administration, as with oral formulations. [1] For this reason, corticosteroids are most effective at targeting individual diseased joints, rather than the horse as a whole. [1]

Corticosteroids also slow the breakdown of cartilage tissues in a diseased joint. [1] Inflammation can activate enzymes within a joint space. [1] By interrupting the inflammatory pathway with corticosteroids, these enzymes do not get activated and the cartilage tissue is preserved. [1]

Clinical Use in Horses

Corticosteroids are used by veterinarians for treating arthritis in any joint of the horse’s body, as long as the joint is accessible for injection. There are reports of using corticosteroids to treat arthritis in the hocks, fetlocks, pasterns, knees, hip joints, and neck. [6][7][8]

Although corticosteroids are common in equine medicine, there are limited randomized clinical trials examining the efficacy and ideal treatment protocols for corticosteroid joint injections in horses.

Overall Efficacy

One large study examining corticosteroid use in 80 lame horses showed that use of TA reduced lameness in 88% of horses by three weeks after treatment. [6]

By three months after treatment, approximately half of the horses returned to their previous level of performance. [6] This suggests TA is an effective treatment for lameness associated with arthritis in horses. [6]

Efficacy in Hock Joints

Most of the corticosteroid studies in horses focus on treatment of the hock joints, as lameness due to hock arthritis is common in horses. [9] Overall, evidence shows that corticosteroid injections are effective in treating lameness associated with arthritis in the hock.

One study examined the efficacy of MPA in treating lameness associated with the lower hock joints. [10] 46% of the horses receiving MPA injections returned to their previous performance level and remained sound for one year. [10] These results suggest MPA is an effective treatment for conditions of the lower hock joint, including arthritis. [10]

Another study followed up on the results of corticosteroid injection in 51 horses with arthritis in a lower hock joint. [11] Lameness improved after treatment in 58% of the horses, however 90% of the horses were still lame at a follow-up appointment. [11]

From these findings, the researchers speculate that while corticosteroids can improve lameness, surgical intervention to treat arthritis may be more effective in some cases. [11]

Finally, a study examining the efficacy of corticosteroids in treating the upper hock joint showed that one out of the three treated horses returned to their previous level of performance for a period of four years. [9] The two other horses were retired due to ongoing lameness issues. [9]

It is important to note horses with arthritis of the upper hock joint have a poor prognosis for soundness overall. Corticosteroids may still be an effective treatment option in spite of these results. [9]

Efficacy in Other Joints

One study examined corticosteroids as a treatment for Equine Wobbler Syndrome (CVSM), a condition that involves narrowing of the spinal canal in the neck. 32% of horses that received corticosteroid injections returned to normal function after treatment, and 39% had improved performance. [7]

In some cases, normal function or improved performance lasted for up to five years following treatment. [7] This suggests corticosteroid injections may improve symptoms in horses affected by CVSM. [7]

A case series examining the outcome of horses with hip joint arthritis showed that treatment with corticosteroids did not significantly improve lameness in affected horses. All horses remained unsound at the walk for the remainder of their lives. [8]

Since hip joint arthritis has a poor prognosis already, researchers hypothesize that corticosteroid injections may be effective in mild cases. [8]

Side Effects

All joint injections penetrate the joint capsule from the outside, they carry a risk of introducing bacteria into the injection site. Other side effects of corticosteroid injections are related to the formulation of the medication and predisposing factors of the individual horse.

Septic Arthritis

Septic arthritis refers to a bacterial infection within a joint, causing inflammation and destruction of the joint cartilage. [1] Septic arthritis is a known side effect of joint injections, as the needle may drag bacteria from the skin surface into the joint. [1]

Symptoms of septic arthritis in horses include: [1]

  • Sudden severe lameness
  • Heat or swelling around the affected joint
  • Pain when touching the affected area

Septic arthritis is diagnosed using bacterial culture of the joint fluid which detects the presence and type of bacteria within the joint space. [1]

Treatment

Treatment is typically intensive and may require hospitalization. Treatments may include: [1]

  • Surgical removal of infected tissue within the joint
  • Repeated lavage of the joint to flush out bacteria
  • Antibiotic injection into the joint space or surrounding tissues
  • Antibiotics given orally, intravenously, or intramuscularly

Around 85-90% of horses survive septic arthritis, however they may develop long-term lameness issues due to joint damage. [12]

Precautions

Although septic arthritis can have serious consequences, this side effect is uncommon due to preventative measures taken by veterinarians prior to performing joint injections. [1]

Preventative measures to reduce the risk of joint infections include: [1][12]

  • Surgical preparation of the injection site
  • Using sterilized equipment, including sterile gloves
  • Administration of antibiotics along with corticosteroids
  • Using small needles that are less likely to carry bacteria through the skin
  • Using new needles for every injection
  • Using single-dose vials to prevent cross-contamination

When performed by a veterinarian using appropriate preventative measures, joint injections pose a low risk of causing infections.

Studies show that septic arthritis occurs in only 0.02%-0.08% of injections in horses. [12] Additionally, the risk of septic arthritis does not increase when injections are performed on the farm rather than in a hospital or veterinary clinic setting. [12]

Joint Flare

A joint flare is an inflammatory response to a joint injection that is not associated with bacterial infection. [1] Estimates suggest that around 2% of joint injections result in a joint flare. [1]

The exact cause of joint flares in horses is unknown, however they may be related to the suspension fluid used in many joint injection medications. [1]

Symptoms of joint flares include: [1]

  • Moderate to severe lameness
  • Pain when touching the affected area
  • Swelling and heat around the affected joint

Joint flares typically resolve on their own, however it can be difficult to distinguish a joint flare from septic arthritis. [1] Most veterinarians treat joint flares similarly to septic arthritis, since septic arthritis can have serious long-term consequences. [1]

Laminitis

There is some concern in the veterinary community that corticosteroid joint injections may trigger laminitis episodes in predisposed horses. [1]

Research shows that injections of systemic corticosteroids, which affect the whole body, can trigger laminitis. Corticosteroids increase levels of the hormone insulin in the blood, which can trigger laminar elongation and weakening within the hoof capsule. [1]

There is an absence of well-designed, controlled studies to assess the risk of laminitis induction by corticosteroid injections into joints and how pre-existing conditions could influence this risk. [1]

However, with the understanding of insulin resistance as a risk factor, and how corticosteroids can worsen insulin resistance, it is believed that preexisting metabolic syndrome can be a contraindication to joint injections.

Corticosteroids can be cleared from the joint and taken up by the blood vessels or capillaries in as little as 12 hours. [13] Therefore, corticosteroids injected into the joint could have effects elsewhere in the body.

Symptoms of laminitis include: [1]

  • “Leaning back” posture to relieve pressure on the front limbs
  • Strong pulses in the digital artery (near the fetlock)
  • Unwillingness to move

Management of acute laminitis involves:

  • Diet of hay with known hydrolyzable carbohydrate (ESC + starch) below 10% or soaked in cold water for one hour
  • Adequate minerals and vitamins to balance the hay
  • Hoof radiographs and trim adjustments as needed
  • Test to rule out concurrent PPID (Cushing’s)
  • Medication as deemed necessary

Competition Use

Many competition organizations have regulations regarding use of corticosteroids in performance horses. [1]

Corticosteroid joint injections may reduce lameness in the short term, allowing an unsound horse to compete when it otherwise could not. [1] Additionally, there is evidence that joint injection of corticosteroids can improve lung function as these drugs can enter the bloodstream and produce an anti-inflammatory effect in other tissues. [1]

Competition organizations with regulations on corticosteroids include: [1]

  • Racing Medication and Testing Consortium (RMTC)
  • Fédération Equestre Internationale (FEI)
  • Equestrian Canada (EC)
  • United States Equestrian Federation (USEF)

Each corticosteroid comes with a specified withdrawal time, which is the mandatory time period that must pass between administration and competition. [1] Horse owners should check specific withdrawal times with their competition organization prior to treatment. [1] Withdrawal times can be up to 28 days in some cases.

Summary

Corticosteroid joint injections are a popular choice among veterinarians to deliver localized anti-inflammatory and pain management effects in horses.

  • Corticosteroid joint injections are a common treatment for arthritis in horses, especially in the hock joint.
  • The anti-inflammatory effect of corticosteroids can reduce pain and lameness in the horse, allowing for a continued performance career.
  • Corticosteroid joint injections are safe for horses when performed by a veterinarian.
  • Corticosteroid joint injections should be used with caution, if at all, in horses with known or suspected metabolic syndrome or PPID

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References

  1. Boorman, S. et al. Review of Glucocorticoid Therapy in Horses: Intra-Articular Corticosteroids. Equine Veterinary Education. 2023.
  2. Caron, J. P. Intra-Articular Injections for Joint Disease in Horses. Veterinary Clinics of North America: Equine Practice. 2005.
  3. Zanotto, G. M. and Frisbie, D. D. Current Joint Therapy Usage in Equine Practice: Changes in the Last 10 Years. Equine Veterinary Journal. 2022.
  4. Ferris, D. J. et al. Current Joint Therapy Usage in Equine Practice: A Survey of Veterinarians 2009. Equine Veterinary Journal. 2011.
  5. Baxter, G. M., Ed. Adams and Stashak’s Lameness in Horses, Seventh Edition. Hoboken, NJ: Wiley-Blackwell, 2020.
  6. De Grauw, J. C. et al. Intra‐articular Treatment with Triamcinolone Compared with Triamcinolone with Hyaluronate: A Randomised Open‐label Multicentre Clinical Trial in 80 Lame Horses. Equine Veterinary Journal. 2016.
  7. Birmingham, S. S. W. et al. Qualitative Assessment of Corticosteroid Cervical Articular Facet Injection in Symptomatic Horses. Equine Veterinary Education. 2010.
  8. Sauer, F. J. et al. Osteoarthritis of the Coxofemoral Joint in 24 Horses: Evaluation of Radiography, Ultrasonography, Intra‐articular Anaesthesia, Treatment and Outcome. Equine Veterinary Journal. 2024.
  9. Fleck, S. K. V. and Dyson, S. J. Lameness Associated with Tarsocrural Joint Pathology in 17 Mature Horses (1997–2010). Equine Veterinary Education. 2012.
  10. Kristiansen, K. K. and Kold, S. E. Multivariable Analysis of Factors Influencing Outcome of 2 Treatment Protocols in 128 Cases of Horses Responding Positively to Intra-Articular Analgesia of the Distal Interphalangeal Joint. Equine Veterinary Journal. 2007.
  11. Labens, R. et al. Retrospective Study of the Effect of Intra-Articular Treatment of Osteoarthritis of the Distal Tarsal Joints in 51 Horses. Veterinary Record. 2007.
  12. Krause, D. M. et al. Comparison of Equine Synovial Sepsis Rate Following Intrasynovial Injection in Ambulatory versus Hospital Settings. Equine Veterinary Journal. 2022.
  13. Evans, C.H. et al. Progress in intra-articular therapy. Nat Rev Rheumatol. 2014.