A Meritable Case
Nov 2, 2011
As She Sees It
Bethany Couture, DVM
At the end of September, our hospital received a case that turned into quite an ordeal. "Merit," as we came to call him, arrived at our clinic with a 3 week history of an infected hock joint. He had been treated aggressively by his primary veterinarian but was not responding well. On evaluation, he was severely lame and had extreme joint effusion. Radiographs showed no significant cartilage or bone abnormalities from the infection. Ultrasound revealed a joint full of inflammatory debris, called fibrin. After speaking with Merit's owners about treatment options, surgery was performed. An arthroscope was used under general anesthesia to view the joint extensively. Fibrin was removed from the joint and a small area of infected bone was debrided. The cartilage surfaces of the joint looked healthy, and a good prognosis was expected as long as no complications arose.
Merit recovered well from surgery and was on the road to recovery. He was maintained on IV antibiotics for several days after surgery and was then switched to oral antibiotics. About 5 days post-op he showed mild signs of colic. General anesthesia causes a decrease in motility of the gastrointestinal tract, which occasionally results in colic. Rectal palpation revealed that Merit had an impaction. Impactions are generally treated medically, with oral fluids, laxatives, and pain medication. After 2 days of medical treatment, the impaction was worsening and Merit was becoming more painful. Another discussion with his owners and we were off to surgery.
Exploratory celiotomy (abdominal exploratory surgery) revealed just what we suspected...an impaction in the pelvic flexure of the large colon. Horses have a GI tract that is riddled with potential anatomical disasters. The pelvic flexure is one of those areas. The large colon is a double horseshoe shaped organ that begins on the right side of the horse, wraps forward toward the diaphragm, then curves backward to the left side. At that point, it narrows and makes a 180 degree turn before wrapping on top of itself back to the right side. The 180 turn on the left side of the horse is called the pelvic flexure. Merit had about 10 inches of very hard ingesta impacted in his pelvic flexure. The only way to resolve the impaction was to open up the colon (enterotomy) and dump it out. Obviously a messy procedure, the colon is incised ahead of the impaction and the material is lavaged out with water. Once the impaction is relieved, the colon is closed and the rest of the abdomen is explored. Merit had no other abnormalities so his abdomen was closed and he recovered uneventfully. He remained on IV fluids for about 24 hours after surgery and was given small amounts of senior feed at about 36 hours post-op. To the dismay of everyone at the hospital, he became colicky about 48 hours after surgery. Rectal exam showed no obvious abnormalities but Merit's pain could not be controlled with medication.
At about the time Merit was colicking again, I was visiting my brother's family for his birthday. Right when we were getting ready to go to the restaurant where we had reserved a room, I get a call from my favorite surgeon saying that our boy Merit needed surgery again. So much for a birthday celebration. I rushed to the clinic and we got him anesthetized and on the table. This time, we found a right dorsal displacement of the large colon. The free end of the colon (pelvic flexure) that I talked about earlier is able to move around at will because it has no connective tissue to hold it in place. When the colon contains no ingesta and becomes gas distended it is very easily displaced because it is not held down by the intestinal contents that it normally contains. We were able to easily put the colon back to its normal position. No other abnormalities were present in the abdomen. Merit again recovered well. We maintained him on IV fluids after surgery and began to feed him back very slowly over 4-5 days, in order to prevent any further GI upset. He became very hungry in record time and resented the small amounts of feed he was receiving, but he recovered superbly.
About a week after the second surgery, Merit's incision became infected. Incisional infections occur in about 25% of horses after one surgery and almost 90% of horses after a second surgery. We began treating him with oral antibiotics but no improvement in the incision was seen after one week of treatment. We submitted a sample from the incision to the laboratory, the sample came back as an extremely antibiotic resistant bacteria. We then put Merit on a very expensive antibiotic for about a week, during which time his incision cleared up well.
Fortunately for those of us at the hospital who were caring for Merit, his infected hock did very well and we never had a complication with it. He was in our care for a total of six weeks, during which time we all became very fond of him. Before all of his medical problems Merit was a very successful racehorse. Merit was discharged from the hospital today. Our hope is that he returns to racing next year in all his former glory. Thanks to his devoted owners for providing him that opportunity.