On Christmas Eve 1995 I wasn’t thinking about cookies or presents, and my only prayer at midnight Mass was “Please let my horse live.” Over and over. Shortly before we left for church, I had given the okay to the equine surgery resident at UC Davis to take my mare to take my mare in for colic surgery. I was a senior veterinary student; I knew the risks associated with pursuing and declining surgery. But, that night, I was just another scared owner saying, “Please let my horse live.”
The GI tract of the horse, housed in that huge abdomen, sometimes seems like a giant black box where any number of things can go suddenly and mysteriously wrong. Many of those things get lumped under the label of colic, but not all of them are equal as far as outcome and expense go. The ability to peek inside that black box and to sort out the risks of each specific disease and the rewards or risks of treatment helps owners and veterinarians to make intelligent decisions regarding care.
This afternoon’s session on critical care of conditions of the gastrointestinal tract helped shed some light into that box, beginning, appropriately enough with a presentation on transabdominal ultrasound to evaluate colic cases. I wish that I had known the information presented by Dr. Michelle Henry Barton 10 years ago. Abdominal ultrasound in the horse has always felt a bit like a specialist’s game to me, but Dr. Barton presented videos in information in a way that made me say, “Hey, I see those distended loops and hairpin turns! I could do that!” She gave concrete examples of four key factors that can help distinguish between surgical and nonsurgical lesions of the small intestine: motility, distension, wall thickness, and intestinal contents. I will also now never forget that the mucosa of a horse with enteritis can look like a lasagna noodle on ultrasound. I also won’t look at my next plate of lasagna in quite the same way!
Dr. Ceri Sherlock discussed impaction of the cupula of the cecum, beginning with a pertinent reminder that cecal rupture can occur with very few preceding signs. After that scary note, however, her presentation was much more encouraging since the post-surgical prognosis for horses with cecal cupular impaction is excellent.
The outlook for neonatal foals requiring colic surgery is also sunnier than one might expect. Dr. Michelle Harris presented a retrospective study of foals hospitalized for colic, and while both the short and long-term survival for foals were not quite as good as for adult horses, the survival rates were still quite respectable, and Dr. Harris said that “owners should not be discouraged from exploratory celiotomy in neonates when indicated.”
Stent bandages, a sort of pressure bandage sutured over the incision site after a colic surgery, decrease the rate of incisional infection from about 28% to 2.7% according to a study presented by Dr. Aziz Tnibar. Dr. Tnibar hypothesized that not only does the stent decrease contamination but it may also reduce the forces of tension on the incision, optimizing the healing environment.
A big question for owners considering colic surgery is “Is it worth it?” Worth might be measured in the likelihood of the horse's survival or it might be measured by the horse’s ability to return to past performance. Two speakers addressed these considerations. Dr. Joy Tomlinson presented a paper on the return to performance and post-surgical earnings of racehorses that underwent colic surgery, and Dr. David Freeman addressed the factors that are clinically relevant to long-term survival of colic surgery.
Both of these presentations should go a long way toward helping owners make informed decisions and toward debunking some of the mythology surrounding colic surgery. Perhaps surprisingly, it turned out that the racehorses that had undergone colic surgery had neither statistically significant shortening of their racing careers when compared to the horses that had placed on either side of them in their last pre-surgery races, nor did they show a significant decrease in post-recovery racing earnings compared to the nonsurgical horses. Of course, these horses did suffer earnings loss during the layup period following surgery.
Many people shy away from colic surgery on older horses, assuming that those horses are less likely to survive the surgery. I struggled with the same dilemma in my mare who was nearly 28 years old that fateful Christmas. However, according to Dr. Freeman’s presentation, old horses do as well after colic surgery as other horses. “They didn't get to be old by not being tough!” My own experience backs that up. Goldie lived another eight years after her surgery, and her eventual euthanasia at age 36 had nothing to do with colic or her surgery. Dr. Freeman did indicate that survival rates do vary with some breeds. Drafts and Minis handle surgery the worst, while Appaloosas fare best. (My personal theory is that Appys are just hard to kill.)
To my knowledge, we don’t see a lot of equine proliferative enteropathy (EPE) due to Lawsonia intracellularis in California, or at least we didn’t in our practice, so I found the last two presentations of the session incredibly informative. Dr. Connie Gebhart presented a comparison of several serologic assays for EPE, and Dr. Allen Page presented a look at variation between years in seroconversion of horses to Lawsonia.
Several of the serology tests look very promising, although they did all seem to be more accurate in weanlings than adults. Total protein also looks quite good as a screening test, which is nice to know since it’s a quick and easy test. Pretty cheap, too.
Dr. Page’s study confirmed the seasonal spikes known for Lawsonia in Kentucky, with peaks in October-November and again in January-February. While there wasn’t any variation from year to year in samples taken from across Kentucky, decreases in the numbers of seroconversions were seen from 2010 to 2011 and from 2011 to 2012 on three farms where the disease is endemic.
And now, with the equine gastrointestinal tract in mind, it is time to go meet my family at Disneyland for dinner and some fun. I’ll be back tomorrow for the last day of AAEP 2012 with information on infectious diseases, neurology, and other fun stuff. Have a good night; I’ll say “hi” to Mickey for you!