In today’s VETgirl online veterinary continuing education blog, we welcome our first large animal veterinary blogger, Kathryn M. Slaughter-Mehfoud, DVM, MPH. She is currently an equine surgical resident at University of Illinois.

Equine Colic – When To Refer
By Kathryn M. Slaughter-Mehfoud, DVM, MPH

Equine ambulatory veterinarians frequently encounter colic with their equine patients. The overwhelming majority of colic patients can be treated medically in the field. However, the horses which require intense medical therapy or exploratory celiotomy must be promptly referred. It is crucial to the colicing horse’s prognosis and survivability to know when to refer the patient to a surgical hospital. Patient signalment, history, physical examination findings, nasogastric intubation, and abdominal palpation via rectum are all important diagnostic aids for effectively and efficiently collecting adequate information for the decision to refer.

Patient Signalment
The decision to refer starts with the phone call. Knowing the age, breed, reproductive status, and athletic use of the horse can form differential diagnoses before the practitioner’s arrival at the barn. For example, senior horses over the age of 15 years old are more prone to strangulating lipomas causing small intestinal obstruction of the gastrointestinal tract and post-parturient mares are predisposed to large colon torsions. These two signalments reflect patients which require immediate referral. However, an athletic horse with an abrupt halt in exercise, whether caused by the end of the show season or an injury, are prone to large colon impactions. This signalment may be manageable in the field depending on the degree of severity. The signalment is the first integral piece of knowledge influencing the decision to refer.

In this VETgirl online veterinary large animal blog, we review all things equine medicine and surgery!

Patient History
Not only is the current history of the colicing horse important, but also the previous medical and surgical history of the patient must be considered when forming the decision to refer. For example, a horse which has episodic colic a few times a year with gas colic or an impaction may be managed on the farm. However, if the horse has had a previous exploratory celiotomy, adhesions may be the cause of colic, which would necessitate referral. Awareness of all short- and long-term medications the horse has received is helpful in forming differentials. For instance, long term use of phenylbutazone can lead to right dorsal colitis. In addition, knowing all medications the horse has received prior to the practitioner’s arrival is essential for adequate pain assessment. If the owner or a different veterinarian has administered multiple doses of a sedative and the horse continues to be painful, referral should be prompt.

Physical Examination
Uncontrollable pain is one of the most crucial factors to evaluate when considering referral. Clinical signs of pain include flank watching, incessant pawing, recumbency, and rolling. The degree of pain is commonly associated with the degree of gastrointestinal compromise. Horses with a non-strangulating lesion of the gastrointestinal tract typically respond well to sedatives and anti-inflammatory/analgesic medications on the farm. On the contrary, horses with a strangulating lesion of the gastrointestinal tract are often refractory to sedation and pain management, which is certainly cause for referral. If pain cannot be reasonably managed, the patient should be immediately referred to a surgical hospital. Even in the absence of other diagnostic abnormalities, intractable abdominal pain is commonly the most significant factor influencing the equine surgeon’s decision for recommending an exploratory celiotomy. Heart rate is an exceptionally reliable measure of pain assessment. An elevated heart rate of 60+ beats/minute warrants referral. Temperature is also a useful physical examination parameter of the colicing horse. An elevated temperature of 101.5+℉ can be caused by colitis, pleuropneumonia, or proximal enteritis. These pathologies do require intense medical therapy, but often do not necessitate surgery. Another essential physical examination parameter is evaluation of the mucous membranes. An increased capillary refill time of 2+ seconds is indicative of dehydration, which depending on other diagnostics, mild dehydration can be corrected in the field. However, a dark line along the gums, known as the “toxic line,” can be present in horses with endotoxemia, which is an urgent sign for referral. Abdominal auscultation for borborygmi is also part of the colic examination. Decreased gut sounds are common with colicing horses, but absent gut sounds can be a sign of a gastrointestinal obstruction, prompting referral.

Nasogastric Intubation
Nasogastric intubation of the colicing horse is not only an essential diagnostic, but also an essential treatment, whether for administration of oral fluids or for relieving pressure within the stomach. Net nasogastric reflux of less than 3 L of fluid is normal and does not suggest imminent referral. Net nasogastric reflux of 3+ L is indicative of a gastrointestinal obstruction, commonly of small intestinal origin. Large amounts of malodorous fluid produced from nasogastric intubation should lead the practitioner to referral.

Abdominal Palpation via Rectum
Abdominal palpation via rectum is a great diagnostic aid to help narrow differential diagnoses for the colicing horse. Palpation of a firm mass to the left of midline is typically indicative of a pelvic flexure impaction, which can often be resolved with appropriate medical therapy in the field. Palpation of the large colon within the nephrosplenic space indicates a left dorsal displacement of the large colon. Left dorsal displacements can be managed medically with phenylephrine administration, but in some instances may require surgery if phenylephrine does not correct the abnormality. Palpation which reveals a significant amount of large colon gas distension can indicate a large colon displacement, which often requires exploratory celiotomy. The small colon is normally palpable with nondistended fecal balls. If a hard, distended tubular structure is palpated with an antimesenteric band, a small colon impaction is likely, which usually requires exploratory celiotomy. In all circumstances, palpation of distended small intestine is abnormal and necessitates immediate referral for suspected small intestinal obstruction.

Colic Referral Decision
Once the practitioner has made the decision the patient needs referred, the practitioner must communicate these findings to the owner. In my experience, one factor which often gets overlooked when referring the equine colic patient is finances. It is common for a painful horse to have a 2+ hour trailer ride to the hospital, the referring hospital details the costs for intense medical therapy or exploratory celiotomy, and then the owner elects to euthanize the horse due to financial constraints. Meanwhile, the quality of life of the horse has been poor for the 2+ hour trailer ride. If a referring veterinarian is ever unsure about estimated costs for referral, they should call the hospital to collect information about finances prior to referral.

Ultimately, the most significant factor influencing the decision to refer is intractable pain. Postponed referral in a painful horse can lead to gastrointestinal rupture, further systemic compromise, and death. Immediate exploratory celiotomy is the priority treatment for an uncontrollably painful horse.

Only VETgirl members can leave comments. Sign In or Join VETgirl now!