Intra-articular administration of antibiotics in horses: Justifications, risks, reconsideration of use and outcomes

Antibiotics have been injected intra-articularly by equine veterinarians for decades, either prophylactically when other drugs are administered for osteoarthritis or therapeutically to treat septic arthritis. This route of administration has also more recently gained attention in human orthopaedic clinical practice, particularly as an alternative to systemic antibiotic administration to treat infections following prosthetic arthroplasty. While the rationale for injecting antibiotics intra-articularly has been largely focused on achieving high local drug concentrations, there has been relatively little focus on pharmacokinetic parameters of antibiotics administered by this route, or on the potential for local toxicity. The increasing incidence of antibiotic resistance in veterinary and human medicine prompts reconsideration of off-label antibiotic usage and evaluation of evidence-based dosing strategies. The purpose of this review was to summarise the current literature describing intra-articular antibiotic usage, including specific studies where pharmacokinetics, potential safety and toxicity have been evaluated. This review will advance practitioners' understanding of the use of intra-articularly administered antibiotics, including the overall pros and cons of the approach.

Clinical management of septic arthritis in cattle

Synovial fluid, ultrasound, and radiographic imaging are common diagnostic tools for septic arthritis. Mycoplasma septic arthritis is suspected in calves with clinical signs of otitis and pneumonia. Commonly affected joints are carpus, stifle, and tarsus. Treatment strategy must include long-term antibiotics, anti-inflammatories, and joint lavage. Knowledge of communication and boundaries for commonly affected joints is essential to perform joint lavage and arthrotomy.

Corticosteroids as an adjunct to antibiotics and surgical drainage for the treatment of pyogenic flexor tenosynovitis

BACKGROUND

Many similarities exist between pyogenic flexor tenosynovitis and other closed-space infections such as septic arthritis. Previous studies have demonstrated that corticosteroids in conjunction with antibiotics considerably improve treatment outcomes in patients with septic arthritis. Using a chicken model, we investigated whether or not corticosteroids in combination with antibiotics and/or surgical drainage could minimize the loss of range of motion typically associated with pyogenic flexor tenosynovitis.

METHODS

We inoculated the flexor tendon sheath of the right long toe of broiler chickens with Staphylococcus aureus (American Type Culture Collection 29523 NA) (6 × 10(9) colony-forming units/mL) and twenty-four hours later administered one of six treatments to groups of fourteen or fifteen chickens. Treatment combinations included systemic or intrasynovial antibiotics, surgical drainage with catheter irrigation or no surgical drainage, and local corticosteroid injections or no corticosteroid injections. Measurements of active digital flexion at the proximal and middle interphalangeal joints were performed before inoculation and treatment and at seven, fourteen, and twenty-eight days after treatment. Flexion measurements were compared between groups as well as with similar measurements in the contralateral, uninfected, control long toe.

RESULTS

At twenty-eight days, two of three groups treated with locally administered corticosteroids and the group treated with intrasynovial antibiotics alone (without surgery) regained significantly more active flexion in comparison with chickens treated with systemic antibiotics and surgical drainage (the current standard of care). Pooled data revealed that the corticosteroid-treated groups regained significantly more active flexion at all post-treatment time points.

CONCLUSIONS

Our data support the hypothesis that adding locally administered corticosteroids to the treatment regimen for pyogenic flexor tenosynovitis in a chicken model can significantly decrease loss of motion resulting from the infection. Furthermore, locally administered antibiotics may be effective for the treatment of pyogenic flexor tenosynovitis.