Cover Story

Time is Not Your Friend When Treating Colic

By Marie Rosenthal

Whether a colicky horse is treated on the farm or in a hospital, time is not your friend.

Although an estimated 90% of horses with simple colic treated in the field recover, many quick decisions must be made to increase the horse’s chances, including deciding whether that horse should be referred, according to Anthony Blikslager, DVM, PhD, a surgeon at North Carolina State University College of Veterinary Medicine.

Heart rate, for instance, is a primary indicator whether a horse needs to be referred, so an assessment of the cardiovascular system is a priority.

“Time is of the essence when making these decisions as I think everyone knows,” Dr. Blikslager said. “What you are doing is trying to reduce the time it takes to get a horse to a referral center if it needs more advanced care. The ultimate goal is to increase survival.”

To speed the initial examination, taking an abbreviated history is appropriate, he explained. Obtain the signalment, severity of pain, how long the signs have been occurring, and any treatments that were already given. The physical examination should include an estimate of distension, as well as an assessment of the cardiovascular system.

More detailed history, such as diet, deworming, etc. can be taken later, according to Dr. Blikslager.

Before arrival, it helps to have some initial information, such as signalment, severity of pain and duration. “Are there signs of mild colic or moderate—the horse is starting to go down and get backs up—or is it severe—the horse is staying down and thrashing?”

Assessing the heart rate either by a pulse on the facial artery or with a stethoscope, observing mucus membrane color, and capillary refill time are important initial parameters.

“The reason for trying to get those important cardiovascular parameters initially is that you can change those with analgesics,” he explained. “The heart rate is the most predictive ultimately of the need for referral.”

Find out if the owner has already given the animal something for pain because that will affect the heart rate, he said.

Dr. Blikslager likes to start with a short-term analgesic, such as a combination of xylazine and butorphanol. This enables the animal to be more comfortable during the initial examination, which also includes auscultation of the chest and abdomen, and nasogastric intubation.

During this time, Dr. Blikslager can get a sense of how the animal is responding to the analgesia. If needed, he will consider a longer-term analgesia like flunixin meglumine if the animal is still uncomfortable.

If there is no response to analgesia—and the pain is severe—he would consider detomidine and referring that animal.

The remainder of the physical examination should include taking a temperature, which is useful for differentiating enteritis or colitis from a simple colic, he said. Rectal palpation also is useful for localizing lesions.

Abdominocentesis can be useful. “Although typically, I am going to reserve abdominocentesis for a patient where I’m pretty sure it’s not a large colon problem. If it’s a small intestinal problem, it’s far more useful.”

Abdominocentesis results can provide “more additional convincing evidence,” if the owner is trying to make the decision to refer, he explained.

Look at the color of the fluid, he said. A light yellow is normal, if there is frank blood, it’s a clear-cut sign that the horse needs to be referred.

Ultrasonography is used heavily in referral centers, he said, but it can also be useful in the field in assessing both large and small intestinal issues.

Another useful tool is measuring lactate. A significantly elevated lactate level can be a marker of an intestinal strangulating obstruction and ischemia, according to Dr. Blikslager.

Treatment for a field colic is typically pain management, laxatives, such as mineral oil, dioctyl sodium sulfosuccinate or Epsom salts, and a fluid therapy plan to manage dehydration.

Although many animals do respond, if the animal does not—the pain is unrelenting, there are signs of endotoxemia, more serious disease or the veterinarian is called for a second colic—the animal should be referred.

“I’d like to break down the reasons for referral a little bit more simply,” he said. “It doesn’t matter what the other findings are showing you, if you cannot control the pain, it’s the horse making the decision for you.

“And in case you are wondering, we do the same thing [in the hospital]. If the horse arrives upside down on the trailer in unrelenting pain, we go right to the induction stall for anesthesia,” he said.

The best success will come from having a rapid, set system for evaluating the horse and deciding if a referral is warranted, he said, but it is essential to let owners know their options and help them understand why that referral might be needed.