Injecting Horse Joints with Antibiotics: Pros and Cons

Because of the finesse with which equine veterinarians inject medications into joints, the procedure can appear uncomplicated. While injecting joints with antibiotics can help clear infections, the procedure is not without risks. Veterinarians must therefore consider a number of important factors before moving forward with intra-articular antibiotic therapies.

Managing Osteoarthritis

Medicating joints with corticosteroids, polysulfated glycosaminoglycans, or hyaluronic acid is commonplace in equine sports medicine. Intra-articular injection is often used in conjunction with other modalities, including oral joint health supplements. Oral products decrease inflammation and improve mobility, boosting the overall health of joints. Examples of appropriate products include high-quality supplements that contain proprietary combinations of glucosamine hydrochloride, chondroitin sulfate, MSM, and hyaluronic acid.

According to a recent review of intra-articular antibiotic use, 78% of veterinarians use intra-articular antibiotics in combination with other medications.^* By adding an antibiotic, often amikacin, to corticosteroid or polysulfated glycosaminoglycan, veterinarians hope to sidestep the development of a septic joint.

Considering the low risk of infection following joint injections, the question then becomes whether or not veterinarians should use prophylactic antibiotics. Moreover, because intra-articular antibiotics are used “off-label,” no researched guidelines for appropriate intra-articular use exist.

Prophylactic intra-articular antibiotic use therefore has two major ramifications:

1. Veterinarians may administer an excessively high dose. “According to some evidence, antibiotics like amikacin have toxic effects on cartilage cells and other joint tissues,” said Peter Huntington, B.V.Sc., M.A.C.V.Sc., director of nutrition at Kentucky Equine Research.
2. Unnecessary use of antibiotics contributes to antibiotic resistance. “With few new antibiotics in development and growing multidrug resistance to currently available medication, revisiting the practice of prophylactic antibiotic use in horses may be warranted,” Huntington added.

These concerns associated with intra-articular antibiotic administration supports alternative strategies for maintaining joint health.

Managing Septic Joints

Intra-articular antibiotics are indispensable in the face of a septic joint because direct administration into the joint can achieve high local drug concentrations. If, on the other hand, antibiotics are offered orally, high dosages would be needed for longer durations to achieve the same result as an intra-articular injection.

“Systemic antibiotics, however, may be associated with important and potentially life-threatening side effects such as gastrointestinal disturbances that disrupt the microbiome. In the face of microbiome disarray, pathogenic bacteria may proliferate, altering immunity and increasing the risk of diarrhea or laminitis,” Huntington explained.  When systemic antibiotics must be administered, gastrointestinal support in the form of research-proven supplements should be considered.

Local antibiotic delivery directly into a joint may also:

• Improve owner compliance as injections do not rely on the owner administering the entire course of oral antibiotics;
• Make treatment more affordable, as a systemic antibiotic maybe be cost prohibitive for an owner;
• Shorten the course of treatment and improve outcomes; and
• Result in high concentrations at the site of infection that may be particularly useful for fighting “floating biofilm,” which is an accumulation of microbes embedded within a self-produced extracellular matrix that helps protect the bacteria from antibiotics.

^*Pezzanite, L.M., D.A. Hendrickson, S. Dow, L. Chow, D. Krause, and L. Goodrich. 2021. Intra-articular administration of antibiotics in horses: Justifications, risks, reconsideration of use and outcomes. Equine Veterinary Journal:13502.