Stanozolol, a synthetic anabolic steroid, is one of many therapies veterinarians have at their disposal for managing joint disease in horses. While used infrequently in the United States and banned in many equestrian sports, it can have its place in certain cases. Scott McClure, DVM, PhD, Dipl. ACVS, ACVSMR, of Midwest Equine Surgery and Sports Medicine, in Boone, Iowa, reviewed stanozolol and its indications during a presentation at the 2022 American Association of Equine Practitioners (AAEP) Convention, held Nov. 19-22, in San Antonio, Texas.

When administered intra-articularly (into the joint), stanozolol can “reduce inflammatory processes and act on synoviocytes (cells in the joint lining) and chondrocytes (cartilage-producing cells) promoting anabolic processes,” explained McClure.

The steroid is not FDA-approved, however, and is banned by the United States Equestrian Federation, Fédération Equestre Internationale, and most racing jurisdictions. For these reasons stanozolol is underused, said McClure, though veterinarians can acquire it from some compounding pharmacies. Certain populations of horses might benefit from this joint therapy, he said, including:

• Young horses with osteochondrosis lesions or subchondral cysts.
• Horses with meniscal injuries to the stifle.
• Racehorses with palmar/plantar (in the fore- or hind-limb) osteochondral disease—a degenerative condition affecting the lower ends of the cannon bones.

For treatment to be successful, said McClure, horses treated with stanozolol must be rested and rehabilitated. The therapy involves a series of weekly injections, often followed by a controlled exercise program.

“Stanozolol should not be considered a quick fix, as the overall goal is for it to allow healing of the joint, including cartilage, synovium, subchondral bone (which is found beneath the cartilage and supports the cartilage of the joint surface), and associated ligaments and menisci,” he added.

Potential side effects include increased joint effusion (fluid swelling) post-injection that can be managed with ice and the non-steroidal anti-inflammatory drug phenylbutazone. While veterinarians can administer stanozolol concurrently with intra-articular hyaluronic acid or antibiotics, they should not co-administer corticosteroids, which can inhibit the therapy’s desired anabolic effects.

“Stanozolol can be a useful component for managing joint disease,” said McClure. “It is an affordable disease-modifying drug, but the veterinarian must be aware of forbidden substance regulations when using it.”