Vet Practice: Managing Horses With Colic in the Field

When horses colic, time is not on your side. Minutes matter, and often both veterinarian and owner must make quick decisions—the veterinarian about treatment and the owner about the financial risk and reward of paying for those treatments. Moving from field management to referral hospital, and potentially surgery, can improve a horse’s chance of surviving but isn’t an option for all owners.

Fortunately, up to 90% of horses respond to on-farm treatment for colic, said Anthony Blikslager, DVM, PhD, Dipl. ACVS, who heads the clinical sciences department and is a professor of equine surgery and gastroenterology at North Carolina State University’s College of Veterinary Medicine. Blikslager shared his decision tree for managing colicking horses in the field during the 2020 American Association of Equine Practitioners’ Convention, held virtually.

“I want you to think about those horses that may need more advanced care and to offer that to owners earlier and, therefore, get those horses to a referral center sooner in case more advanced techniques such as surgery are needed,” Blikslager said.

Help Clients Prepare for a Colic Emergency

Many horses live under the care of trainers or barn managers. For those horses, it’s important for owners to sign consent for care waivers and declare their intentions in case of a veterinary emergency, such as colic, and whether they want their horse referred or would consider surgery if necessary. The horse’s insurance paperwork should also be in order, Blikslager said. This preparation can expedite care.

“It just makes it much simpler in case the owner is not available,” Blikslager said.

Additionally, farms must have pickups and trailers “just flat ready to go,” Blikslager said. “So as soon a decision is made, it’s not in the middle of the night, and they’re looking for a truck separate from a trailer and trying to get that sorted out. Those things are just going to prolong the time it takes to get a horse to a referral center.”

Colic Care Starts With an Efficient Exam

Managing colic in the field centers on early recognition of clinical signs and treatment of pain, Blikslager said. He recommends aiming for a rapid initial colic exam that takes 20-30 minutes or less.

The initial exam includes estimating abdominal distention and evaluating heart rate (an increased pulse is the most important indication of pain severity, he said), gum color (pink is normal, pale or abnormal colored indicates shock), capillary refill time, and listening to the chest and taking the horse’s respiration rate. He then recommends moving quickly to listening for abdominal gut sounds to see if they are active. He also recommended taking the horse’s temperature—a fever might indicate a differential diagnosis, such as infection or enterocolitis. Skin tenting (the amount of time skin on the neck stands after being pinched—normal is 2-3 seconds) can also indicate dehydration. Blikslager mentioned that this can be misleading in older horses with less elastic skin.

The more severe the horse’s pain, the more quickly this exam should go, he said.

Finally, Blikslager passes a nasogastric (NG) tube to check stomach contents and for reflux. “Anything less than 2 liters of fluid (coming up the tube from the stomach) is normal,” he said. He added that the fluid’s pH and the amount of gas coming off the stomach isn’t as important as the amount of fluid expressed.

Additional history, such as diet and deworming, can be taken later after pain management is underway, he said.

Managing the Horse’s Pain Is Key

For severely painful horses requiring care at a referral hospital, making that decision early increases the chance of survival. “Some things make that decision very easy, such as you can’t manage the horse’s pain,” he said. “Sometimes the horse is going to make that quite difficult for you to figure out.”

Recent research resulting in the Equine Grimace Scale has offered a more nuanced understanding of signs horses are in pain. These include, but aren’t limited to, orbital (eye) tightening, tension above the eyes, and stiff, turned back ears.

Veterinarians have a variety of analgesic drugs to choose from in managing colic pain—some, such as flunixin meglumine (Banamine), the farm might have on hand as well. For that reason, Blikslager emphasized, the veterinarian needs to find out if the horse has already received medication and, if so, what, how much, and at what time. For example, the horse presenting as painful after the owner has already given the horse flunixin or firocoxib could indicate the colic is more severe than if no drug had been administered. Additionally, excessive dosing can lead to other problems, such as renal (kidney) failure in the case of flunixin overdose.

“My preference would be to use a short-duration analgesic,” he said, specifying the alpha 2 agonist xylaxine and the opioid butorphanol.

“The nice thing about these analgesics is that they’re only going to last 30 to 40 minutes,” Blikslager said. “One of the key things you’re going to be looking for is how does the horse respond to analgesia, and in the time it takes you to do an exam and get the history, get the treatments administered, and get it all wrapped up, you’re going to know whether that horse has recurring pain or not.”

Recurring pain indicates the need to talk to the owner about referral, and if the pain is severe enough and continues to recur, a discussion about euthanasia if the owner does not want to or cannot refer, he said.

Horses that present as severely painful might need detomidine, a more potent and longer-acting painkiller. “This is the most potent analgesic you’re going to have on the truck,” he said, adding that horses exhibiting this level of pain probably need referral.

Continued Field Treatments and Examinations

Beyond the initial exam and pain management, Blikslager noted treatment and exam options for the field that help the veterinarian resolve the colic or gather information to prompt referral. Those include:

Administering laxatives via NG tube. The most commonly used laxatives are mineral oil, dioctyl sodium sulfosuccinate (potentially fatal at a threefold overdose), or Epsom salts mixed with water (higher doses can cause hypermagnesemia, or excess magnesium in the bloodstream). Beyond potentially moving material through the gastrointestinal tract, the expelling of mineral oil on the anus or tail can give the veterinarian an idea of GI transit time (which should take about 18 hours). Blikslager noted that the gastrocolic reflex (a physiological response to stomach filling that stimulates intestinal motility) might be the most important effect of administrating any of these laxatives.

Rectal palpation. This is the most useful diagnostic for localizing lesions, Blikslager said. Veterinarians should know landmarks so they can identify any abnormalities or impactions.

Ultrasound. “I would encourage you to use it in the field for those cases where we are on the fence about what to do or the owner is indecisive and you feel like you need more evidence as to what’s going on (to convince the owner for referral),” Blikslager said.

Abdominocentesis. This puncture of the abdomen by a needle allows the vet to withdraw fluid and evaluate its color (yellow is normal), total protein, and lactate amount.

Fluid therapy. Administering intravenous fluids is possible in the field, Blikslager said. However, most veterinarians will refer the animal to a clinic for this treatment.

Decisions Continue for Referred Cases

For those horses that do get referred to a clinic or hospital, care decisions continue for the veterinarian. For example, some might require medical care, such as hydration or continued pain management. Others might need surgery. “At our University, for example, only about 50% of the horses that come in need surgery,” Blikslager said “but we are always happy to take all referrals, realizing that the more horses that are referred, the less we will miss horses that are in need of advanced medical or surgical care.”

Take-Home Message

For veterinarians, communicating with owners before and during a colic is important to providing prompt and often life-saving care. Vets should develop an efficient field colic exam they are comfortable performing, which enables them to move to indicated treatment quickly. Pain management is key to resolving colic cases on the farm, and owners are urged to involved their veterinarians as soon as possible in treatment and decision-making for horses with colic. When necessary, making referral decisions quickly increases horse survival rates. Time to referral is the one factor that has been the hardest to manage over the years, Blikslager said.