Wounds in the joint space
"Any significant traumatic wound of the distal limb that is in close proximity to a joint should be treated as if the joint
were invaded until proven otherwise," Jann cautions.
It is important to determine if the wound is in a joint space, and there are techniques to do this.
The joint can be palpated, radiographed or saline may be injected into the joint to see if it comes out the wound.
"If we're not sure, I would rather be on the safe side," Jann states. Use antibiotics, clean the wound and use regional perfusion
to make sure the wound is kept free of infection.
If septic arthritis sets in, it is unlikely the horse will be functional again.
"Septic arthritis is a condition that should be avoided at all costs," Jann says.
"The old adage about an ounce of prevention being worth a pound of cure applies to the correlation of wounds of the distal
limb to the potential for septic arthritis in one of the diarthrodial joints, particularly the fetlock, tarsus and carpus,"
The severity of joint contamination and/or infection are highly influenced by rapid and aggressive treatment.
Stepwise treatment for joint-space wounds includes inspection, antimicrobial therapy and lavage.
After wound margins are thoroughly cleansed and prepped to prevent contamination of the deeper aspects, especially if joint
spaces are suspected of being involved, the wound should be inspected digitally.
The easiest way to determine if the synovial space has been compromised, even minimally penetrated, is to assess its permeability.
Sterile saline injected intra-articularly with sufficient pressure to distend the joint fully, with leakage noticed in or
around the wound location, will indicate joint capsule involvement.
If that is the case, the serious nature of the wound (i.e., from a minor laceration to a career- or life-threatening event)
should be conveyed to the client. With the joint space compromised, it is of critical importance to treat the wound within
24 hours to ensure a good outcome — 85 percent survival, 50 percent for return to function.
Suspicion of joint involvement also makes it critical to use a broad-spectrum antibiotic immediately. Based on serial culture
and sensitivity, the proper drug should be selected and then continued for three to six weeks, or for two weeks after clinical
signs have been resolved.
Once joint involvement has been determined, lavage is important. This is best done under general anesthesia, via arthroscopy
in a surgical setting, though it may be done in the sedated standing animal under field conditions.
Use copious fluids (i.e., providone iodine-lactated Ringer's), with the wound carefully debrided.
"Most of the wounds we see in horses' extremities are so infected, quite frankly if a person had a wound like that and went
to a surgeon, he would probably just amputate," Jann says.
But, unlike people and dogs, who can function on less than their full complement of limbs, horses need all four legs to function.
Overall prognosis for flexor-tendon lacerations is favorable. Wounds that involve tendon sheaths can be successfully treated
with a favorable prognosis.
So too is the prognosis for extensor-tendon lacerations in the non-sheathed and sheathed zones.
For joint-space wounds, aggressive therapy, initiated within hours of the injury, is essential for a favorable prognosis.
Kane is a Seattle author, researcher and consultant in animal nutrition, physiology and veterinary medicine, with a background
in horses, pets and livestock.