Standing up to colic
Nantucket had been with his new owners for only one month when the colic struck. The 5-year-old Thoroughbred-cross gelding was purchased as a potential show hunter, but he hadn’t yet made it to his first competition when his new family found him one morning pawing, restless and uninterested in his feed.
The local veterinarian came out right away, and he agreed with the family’s assessment that the colic was still mild: The gelding was far from the frantic, sweaty state that means acute gut pain. Nevertheless, the veterinarian began a full diagnostic workup.
A check of vital signs revealed only a slightly elevated heart rate. Next, the veterinarian passed a nasogastric tube to check for a buildup of fluid in the gelding’s stomach, but only a small amount flowed from the tube into the waiting bucket, which was an encouraging sign. The rectal palpation, however, yielded some troublesome findings. Nantucket’s large colon felt like an inflated beach ball---a sign of gas buildup.
The veterinarian gave the gelding a dose of Banamine. Often, mild colics will subside after the painkiller is administered because the horse is able to relax, which allows gas to move and normal gut activity to resume. Hoping for an easy resolution, the veterinarian told Nantucket’s owners to keep a close eye on the situation and to call immediately if the gelding took a turn for the worse.
Nantucket didn’t get any worse over the course of the day, but he didn’t get any better, either. That evening the
Nephrosplenic entrapment occurs when the large colon slips upward over the spleen and gets caught on the nephrosplenic ligament, which connects the spleen to the left kidney. The ligament is located near the abdominal wall of the left flank, toward the top of the body. When the colon gets trapped against this ligament, gas and feed cannot move easily through it, causing a backup that leads to colic pain.
Why this condition occurs is not known. “There are a few theories,” says Clarisa Krueger, DVM, of Elgin Veterinary Hospital in Elgin, Texas. “There are nerve plexus in the colon, responsible for normal motility, and if those plexus fire wrong you can get some abnormal motility of the large colon, which allows more gas to build up and the colon to shift in position. There’s also a notion out there among horsepeople that it’s caused by rolling, which cannot be ruled out as having a role in colic, but I’m pretty sure that’s not true. We’d have horses trapping their colons on a daily basis if rolling caused it.”
Nevertheless, Nantucket showed the two classic signs that point to this diagnosis: an “inflated” colon caused by the backed up gases and food matter, combined with the shift in the position of the large colon and spleen.
The local veterinarian went over treatment options with the gelding’s owners. If Nantucket had been showing signs of severe pain---such as thrashing, sweating or a highly elevated heart rate---the first recommendation would have been immediate transport to a clinic for emergency surgery.
However, because Nantucket’s pain was still fairly mild, the veterinarian suggested trying a more conservative treatment first: The gelding would be injected with the drug phenylephrine,