Joint Infections in Horses

Joint infections can be categorized in two ways:

Acute joint infections: acute infections arise suddenly in a short period of time, usually due to a wound, puncture, or joint injection

Chronic joint infections: chronic infections have been present for a longer period of time, and usually develop from untreated acute infections. Long-standing infections are more difficult to treat, and are more likely to develop secondary complications.

Joint infections are always an emergency and require immediate attention. Infected joints left untreated are likely to develop severe complications that often result in euthanasia. Horses unable to bear weight on a limb always require medical attention.

Joint infections are most commonly caused by a puncture or cut around the joint that enters the joint space and allows bacterial entry. Joint fluid is a highly nutritious medium for bacterial growth, rapidly resulting in severe bacterial infections.

Joint infections are a rare complication from routine joint injections. Veterinarians mitigate this risk by thorough scrubbing and cleansing of the injection area; however, any object entering the joint space can potentially introduce bacteria into the joint.

Bacteria can also enter the joint space through a blood infection. This type of joint infection is most common in foals. In foals, an infection can begin in the womb after bacterial transfer from the mother, or through contamination of the umbilical stump after birth. In some cases, foals can inhale or ingest bacteria, causing a blood infection, leading to joint infections.

If an infection is suspected, it is crucial to begin treatment as soon as possible. Diagnostics include:

• Physical examination
• Synovial fluid analysis
• Imaging (x-ray, ultrasound, MRI, CT scan)
• Culturing of bacteria from in or around the wound

If the infection is acute, primary treatment involves antibiotics and flushing the joint with sterile saline to remove contamination. Standard wound care such as stitches, routine cleaning, topical medications, bandaging, and stall rest are often components of treatment.

Chronic infection requires more aggressive treatment, including open joint drainage, surgery, prolonged antibiotic treatment, and arthroscopy.

Treatment depends on severity and the level of progression, but includes:

• Antimicrobial drugs
• Intra-articular antibiotic injections
• Regional limb perfusion: localized treatment where the site of infection is isolated and concentrated antimicrobials are injected directly into the veins
• Arthroscopy
• Supportive care

Treatment can be intensive and requires repeated monitoring and time. In more extreme cases, long-term effects of treatment can lead to osteoarthritis, bone infections, and an inability to return to previous performance level. Foals, regardless of whether the infection is acute or chronic, often require intensive treatment protocols.

If the condition is rapidly recognized and treatment begins immediately, prognosis is good for recovery and return to previous athletic performance. The longer the infection is left untreated, the poorer the prognosis. Complications include osteomyelitis (bone infection) and opposing limb laminitis. Severe joint infections can also result in osteoarthritis that may prevent return to athletic careers. In some extreme cases, euthanasia is the only humane option.

The best way to prevent a joint infection is to check for wounds around the joint routinely and seek medical care immediately when any injuries are noticed. Infections that are caught and treated early have the best prognosis. Joint infections in horses are not contagious.

Joint infections are common in horses.

• Antibiotics
• Flush with saline
• Open joint drainage
• Surgery
• Arthroscopy
• Stall rest