A nail, a wire, anything sharp. The sort of thing that doesn’t belong anywhere near a horse’s foot. Unfortunately, things like this do sometimes end up puncturing right through the frog or heel and up into the navicular area. When that happens, infection could set in, and the results can be devastating.
While surgery alone can improve the outcome of septic navicular bursitis, recent study results suggest outcomes are even better if surgery is combined with antimicrobial therapies, said David G. Suarez-Fuentes, DVM, who previously worked and conducted the study at Iowa State University (ISU) College of Veterinary Medicine, in Ames. When surgeons combine those therapies with the use of a special lifting bar shoe, success appears even more likely.
“We report the approach to the surgical procedure (navicular bursotomy) with the addition of the use of antimicrobial regional limb perfusions (not previously reported in combination with the bursotomy) in combination with systemic antibiotics to treat the contaminated and/or infected bursa,” Suarez-Fuentes said.
Specifically, he and colleagues at ISU performed navicular bursotomies on 19 horses under general anesthesia. The procedure mainly involves removing part of the frog and digital cushion and cutting through the deep digital flexor tendon to access the navicular bursa, which they debride (remove infected and/or decaying tissue), clean, and rinse. During the surgery, they infused either gentamicin sulfate or amikacin sulfate—both antimicrobials—directly into a digital vein. The scientists continued these infusions every 24 to 48 hours for two to three more treatments after surgery.
They also gave the horses intravenous and/or oral broad-spectrum antimicrobials (penicillin, gentamicin, trimethoprim, and/or sulfadiazine) systemically, before and after surgery, Suarez-Fuentes said. They prescribed postsurgical antimicrobials for up to 21 days.
Once the surgeons completed the operation, they applied a therapeutic patten bar shoe (which features a raised bar that extends between the heels and increases the angle between the hoof and the ground) with a treatment plate (to cover the wound while allowing easy access for medication) on most of the horses, he said. Beyond acting as a fancy bandage, the shoe’s unique design decreases strain on the digital flexor tendon, which is particularly helpful given that a part of that tendon must be cut for the surgeons to reach the navicular bursa.
“(We suggest that) raising the heel increases comfort and increases the horse’s ability to walk with a more correct gait, which can potentially decrease the incidence of scarring and encourage the foot to grow in a more normal fashion,” Suarez-Fuentes said.
Most of the horses—16 out of 19—returned to their previous level of exercise, said Suarez-Fentes. The remaining three became pasture sound or performed at a reduced athletic level. That’s encouraging considering there’s a relatively high risk of ongoing lameness after standard navicular bursotomy surgery alone, and some horses don’t even survive, he said.
“The treated horses in this study responded favorably to the surgery and treatment, and even the majority of the horses were able to return to their intended use (even athletic use),” he said. “We only report 19 cases, which is always a limiting factor of the study, but overall we feel that it’s a procedure to consider when horses are diagnosed with the condition.”
The navicular bursa becomes infected when a foreign body like a nail or wire penetrates through the frog or heel up into the navicular bursa or other nearby structures within the synovial (joint) area, such as the coffin joint or the digital tendon sheath, he said.
But trauma isn’t the only source of infection, he added. It can result from chronic foot abscesses or, rarely, from repeated navicular bursa injections.
“The condition can be seen commonly in horses,” Suarez-Fuentes said. “If it’s not identified and treated early, it can have devastating results for the affected horses.”
Sometimes difficult to diagnose, the condition might require advanced imaging such as MRI to achieve a diagnosis and begin proper treatment, he said. Owners should have a veterinarian examine their horses immediately if there’s any risk of a foreign object puncturing into the foot.
“Penetration of the navicular bursa and/or synovial structures is a major concern,” Suarez-Fuentes said. “The horse must be seen by a veterinarian quickly and treated aggressively.”
The study, “Outcome of horses undergoing navicular bursotomy for the treatment of contaminated or septic navicular bursitis: 19 cases (2002–2016),” was published in the Equine Veterinary Journal.