Septic arthritis in foals - DVM
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Septic arthritis in foals
Consider septic joint, epiphysis or physis for all lame neonate foals


DVM360 MAGAZINE


Treatment of a septic joint is directed at providing immunologic support, anti-microbial coverage and specific joint health maintenance. Immunologic support is accomplished with the use of intravenous plasma to increase immunoglobulin levels. Antimicrobial coverage is directed at the selection and administration of the most effective antibiotic both systemically and locally. Specific joint health maintenance is aimed at removing the proteolytic enzymes that are present in the diseased joint and restoring the viscosity of the joint fluid.

Systemic antibiotics are not effective in eliminating the deep-seated synovitis or osteomyelitis in most cases. Intra-articular antimicrobial injection achieves very high local concentration of the drug, much greater than that which can be achieved by systemic antibiotics alone. Lloyd et al. found that synovial gentamicin concentration in E. coli experimentally infected joints was 1,000 times greater in joints that had received intra-articular gentamicin than in joints of those animals that had received only systemic gentamicin. In addition, the levels remained above MIC of most pathogenic organisms for at least 24 hours.

Regional limb perfusion (RLP) of antibiotics is also a useful technique in achieving high local concentration of antibiotic to the infected synovial lining or bone. RLP is best performed in the anesthetized foal.

Joint lavage has been a technique to relieve the tension on a joint and diluting the inflammatory products. Joint lavage is also best performed in the heavily sedated or anesthetized foal. A through and through lavage with sterile saline may be adequate in joints that don't have much fibrin and don't have bone involvement (Photo 2). For difficult joints, such as the shoulder and hip, a single needle can be used to distend and aspirate the joint.

In joints where there is a large amount of fibrin as evidenced by ultrasound or poor flushing or there are epiphyseal lesions that connect to the joint, arthroscopic evaluation, and large volume flushing is helpful. Subchondral lesions can be curetted and fibrin removed. In chronic nonresponsive joints, arthrotomy with open or closed drainage may be indicated.

Other adjunctive therapies that may be helpful for the foal with septic arthritis include the use of chondroprotective agents. The oral administration of chondroitin sulfate and glucosamine can be administered easily to effected foals. The use of hyaluronate sodium also has been advocated in effected foals.

Septic arthritis/osteomyelitis is an emergency situation. Delayed treatment can result is permanent orthopedic damage. Septic arthritis or "joint ill" was a death sentence to foals in the past. Short-term survival of effected foals has improved greatly during the last 20 years. The keys to success with effected foals are early recognition and aggressive therapy.

It is also important to look at the future productivity of effected foals when discussing prognosis with owners. Therapy is expensive. In general, foals with septic arthritis/osteomyelitis have long hospitalization times, multiple anesthesias for joint lavage and RLP, long-term antibiotics and possible arthroscopic surgery. Sometimes, financial constraints from the owner limit the aggressiveness of the treatment, and they can lead to euthanasia.

Studies looking at the racing performance of horses that had septic arthritis as foals suggest that this disease does decrease, but doesn't eliminate, the chance of the horse making it to the races. No studies have looked at the athletic careers of formerly effected foals that were not destined to be racehorses. It is possible that formerly effected animals can have a good prognosis for less-demanding activities.

Dr. Mary Rose Paradis has been on the faculty of Tufts University School of Veterinary Medicine since 1983. Currently, she is an associate professor in the Department of Clinical Sciences and the director of the Marilyn Simpson Equine Neonatal Intensive Care Unit at Tufts. She earned her DVM from University of Georgia in 1978 and her MS from Washington State University in 1980. She completed residency training at Washington State University (1978-1980) and Michigan State University (1980-1981). She was in an equine private practice on Long Island, N.Y. for 2 years before coming to Tufts.

Dr. Paradis is a diplomate of the American College of Veterinary Internal Medicine (ACVIM) in the Specialty of Large Animal Internal Medicine and currently is ACVIM's president. Her clinical and research interests lie in the diseases of the equine neonate and geriatric individual, two ends of the age spectrum. She currently is editing a new, case-based equine neonatal medicine book.


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