Infections in synovial structures, such as joints and tendon sheaths, require prompt and aggressive veterinary treatment before they progress to causing more serious chronic lameness issues. Flushing joints to remove debris and administering antibiotics are two viable treatment options. Alternatively, a technique called intravenous regional limb perfusion (IVRLP) can deliver high levels of antibiotics to the affected synovial structure. But in the face of growing antibiotic resistance, selecting an effective antibiotic for this use can be tricky.

At the 2016 American Association of Equine Practitioners Convention, held Dec. 3-7 in Orlando, Florida, Robin Fontenot, DVM, MS, Dipl. ACVS, recapped a study in which she and colleagues determined that a drug called meropenem could fit the bill, providing it’s used appropriately.

Fontenot, an assistant clinical professor at Mississippi State University’s College of Veterinary Medicine, said reported pathogen resistance to meropenem, a broad-spectrum bactericidal, is minimal, making it a good potential choice for IVRLP in synovial infections that aren’t responding to other antibiotics and where resistance is an issue. She and colleagues tested the drug by performing IVRLP on 10 healthy horses.

They placed a catheter in the right forelimb of each horse, just above the carpus (knee) in the cephalic vein. Then, they applied a tourniquet above the catheters and administered 500 mg of meropenem diluted in 20 mL of saline. Finally, the team measured the amount of meropenem in synovial fluid obtained from the radiocarpal joints (the top joint in the knee) at varying timepoints for 18 hours following treatment