How Veterinarians Assess Horses With Acute Colic

How Veterinarians Assess Horses With Acute Colic

A complete, thorough, and timely workup has the greatest effect on successfully treating colic.

Photo: Kevin Thompson/The Horse

Just a few decades ago, it was a coin toss whether a horse suffering from acute colic would survive. Today, that figure is closer to 80%, thanks to factors such as faster intervention, earlier referrals, and improved surgical techniques and experience.

At the 2016 American Association of Equine Practitioners Convention, held Dec. 3-7 in Orlando, Florida, Barbara Dallap Schaer, VMD, Dipl. ACVS, ACVECC, described how to assess horses with acute colic. Dallap Schaer is an associate professor and the medical director of the University of Pennsylvania School of Veterinary Medicine’s New Bolton Center, where she said survival to discharge from colic surgery is approximately 90.8%.

“A complete, thorough, and timely workup of the horse with acute abdominal discomfort has the greatest effect on successfully treating colic,” she said.

That initial workup, which the veterinarian can perform in the field or the clinic, includes a physical exam, abdominal palpation per rectum, an ultrasound exam, and nasogastric intubation to check for reflux.

During the rapid physical assessment, the veterinarian should note the “severity and nature of pain, mucous membrane color, pulse quality, jugular refill time, degree of abdominal distension, heart rate, respiratory rate, and rectal temperature,” said Dallap Schaer.

Then he or she proceeds to abdominal palpation per rectum, which can help identify whether the colic is large or small bowel-related, can be categorized as an impaction or distension, or requires surgery, among other findings. Horses that don’t improve or have a change in clinical signs or discomfort might require repeat palpations and are more likely to need surgery.

“Despite advances in ultrasonography, abdominal palpation per rectum remains a mainstay of the colic workup,” said Dallap Schaer, adding that each practitioner will have his or her systematic approach to palpation.

Beware of Colic “Imitators”

During routine colic workups, Barbara Dallap Schaer, VMD, Dipl. ACVS, ACVECC, an associate professor and the medical director of the University of Pennsylvania School of Veterinary Medicine’s New Bolton Center, and her colleagues sometimes come across horses displaying colic-like behavior that’s not gastrointestinal in nature.

It’s important to be aware of these conditions, as “misdiagnosis or delay in treatment could negatively affect outcome,” she said.

Common causes of noncolic-related colic behavior include:

  • Rabies;
  • Tetanus;
  • Exertional rhabdomyolysis, or tying-up;
  • Botulism;
  • Uterine artery rupture;
  • Hyperammonemia;
  • Pheochromocytoma;
  • Red maple or jimsom weed ingestion;
  • Cantharadin toxicity from blister beetles; and
  • Adverse reactions to drugs such as the long-term tranquilizer fluphenazine.

“It is safe to say that few of these patients would benefit from inadvertent exploratory celiotomy (abdominal surgery), and a delay in treatment could certainly decrease chances of survival,” said Dallap Schaer.

Alexandra Beckstett

Another critical component of the colic workup is passing a nasogastric tube through the nostrils into the stomach to relieve pressure and pain due to reflux buildup. The veterinarian will also administer an analgesic, such as flunixin meglumine (Banamine) or phenylbutazone (Bute), an anti-spasmodic, or a sedative to help control and stabilize the horse’s pain.

Further diagnostics include ultrasonography to quickly identify colic-causing lesions, and abdominocentesis, to sample peritoneal fluid in the abdominal cavity for abnormal color or protein content.

Dallap Schaer said findings that would indicate the need for referral to a clinic include:

  • Unrelenting or unmanageable pain;
  • Hypovolemia (dehydration);
  • Tachypnea (increased respiratory rate);
  • The hyperemic (red) mucous membranes or the presence of a toxic line (a bright red or purple line on the gums indicative of endotoxemia);
  • A large volume of gastric reflux; and 
  • Clearly abnormal findings on palpation.

The referring veterinarian’s as well as attending emergency clinician’s findings might indicate the horse needs surgery, and the plan should be a collaborative effort between the owner, referring vet, and surgeon, said Dallap Schaer. Clues that a horse needs surgical intervention include a thickened small intestine, palpable intussusception (when an intestine "telescopes" inside a portion of itself), abnormal peritoneal fluid on abdominocentesis, failure to respond to aggressive medical treatment, and possibly cecal impaction.

“It is important to remember that timely referral, thorough evaluation, and appropriately timed surgical intervention have likely been the greatest contributors to the improved prognosis for colic in the last 10 years,” said Dallap Schaer.

About the Author

Alexandra Beckstett, The Horse Managing Editor

Alexandra Beckstett, Managing Editor of The Horse and a native of Houston, Texas, is a lifelong horse owner who has shown successfully on the national hunter/jumper circuit and dabbled in hunter breeding. After graduating from Duke University, she joined Blood-Horse Publications as Assistant Editor of its book division, Eclipse Press, before joining The Horse.

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