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]</