How to Manage Severe Colic in the Field

1. Introduction

Criteria for referral to a hospital and for surgical intervention for horses with colic have been well established. However, the focus of this presentation is different and has been imposed on many of us by a harsh economy, specifically management of the colic patient when referral is not an option. Under these conditions, the challenge will be to clearly identify when to forge on and when to euthanize.

Most horses with colic can be treated medically on the farm, but we all can recognize when a horse should be referred to a surgical facility. When that point is reached and the owner declines referral, you must then establish some very clear guidelines for how to proceed. The following questions must be addressed:

Why is referral not an option? Possible answers are:

1. Colic surgery is rarely successful.
2. This is a pregnant mare and it will be impossible to save the mare and foal.
3. This is an old horse and old horses do not handle colic surgery well.
4. This horse is much loved/valued, but we cannot justify spending the money on colic surgery in our present financial circumstances.

Answers 1 to 3 are simply untrue. Answer 4 is a reality and probably one that all owners should consider even before any horse they own develops colic. Even in a good economic climate, one must decide which horses in the barn warrant colic surgery and which ones do not. This is always a tough decision.

Once the owner elects treatment at home over referral, the following questions arise for the owner to answer:

1. How much am I prepared to spend? What is my financial limit on this horse? This is critical because you or your colleagues must be compensated for your services. Cases like this can drag on for days and entail several visits. Farm calls, drugs, and intravenous fluids all add up. Nonsurgical treatment at home could approach the cost of nonsurgical treatment at a referral hospital.
2. How much of my time am I prepared to commit to around-the-clock monitoring and care?
3. Can I handle watching a horse suffer, and what are my limits on that (property damage)?
4. Is my family supportive of this decision?
5. Will I change my mind or stay the course?

Once the owner elects treatment at home over referral, the following questions arise for the veterinarian to answer:

1. Do my colleagues and I have the time to devote to this case?
2. How much time do we have to commit to around-the-clock monitoring and care?
3. Do we have the diagnostic capabilities to handle this case and assess its daily progress (ultrasonography, laboratory access with a rapid turnaround)?
4. Do we have the drugs and equipment needed to handle this case?
5. Can I handle watching a horse suffer, and what are my limits on that?

2. Specific Diseases and Recommended Approaches

Displacements that are occasionally treated by surgery, such as right dorsal displacement and impactions of the ileum, cecum, large colon, and small colon, can respond to medical treatment if managed appropriately and given enough time. Entrapment of the colon over the nephrosplenic ligament is usually treated nonsurgically (rolling or phenylephrine) at referral hospitals and could be managed in the same way at home. In very rare cases, large colon volvulus can spontaneously correct. On the other hand, some horses can start with an impaction that produces sufficient gas buildup to cause displacement or volvulus. Strangulating lesions of the small and large intestines are the challenge if surgery is not an option because these will not resolve medically and should be candidates for euthanasia as soon as the diagnosis is made.

Euthanasia should be considered early in the decision process for horses with evidence that supports a diagnosis of strangulating lipoma. Horses older than 10 years should be considered as having a strangulating lipoma, unless proven otherwise, and the likelihood of this diagnosis increases with increasing age. Supportive findings are small intestinal distention, reflux, congested mucous membranes, and increased heart rate. Pain can be absent or mild in older horses. It is not unusual for horses with this lesion, despite the severity of intestinal ischemia, to survive for 3 days or more with reflux and increased heart rate but little evidence of worsening in disease severity.

A horse that cribs is at risk of colic more than non-cribbers, especially strangulation in the epiploic foramen. Strongly supportive findings for this latter diagnosis are small intestinal distention, male horse <20 years old, and Thoroughbred; however, all other breeds and either sex can be affected. Pain can be highly variable in these horses, from mild to severe. Horses that meet these criteria should be under early consideration for euthanasia if all other findings support a diagnosis of small intestinal strangulation.

A postpartum mare with extreme pain and worsening abdominal distention probably has a large colon volvulus. Such cases respond poorly to analgesics, and euthanasia is warranted early in the disease course.

Male intact Standardbreds, Tennessee Walkers, and Saddlebreds are at risk of inguinal hernia and therefore must be examined for this lesion, as should all intact male horses with colic. Although most affected horses are treated with surgery, this condition can be managed by anesthetizing the horse, placing it in dorsal recumbency, and manually reducing the hernia by external massage along the cord as it is stretched taut. Alternatively, the intestine can be drawn away from the vaginal ring per rectum with the horse anesthetized and in dorsal recumbency, although this carries a high risk of intestinal or rectal injury.

American Miniature Horses are prone to fecaliths in the small colon and typically present with marked abdominal distension. Colic in these horses can be very complicated because food deprivation is recommended as part of treatment but can cause hyperlipidemia, liver disease, and death. Euthanasia is recommended in these horses with colic of any cause once signs of hyperlipidemia develop (icterus, depression, lipids in serum) when referral is not an option.

In general, enteroliths might be indistinguishable from an impaction with digesta, based on clinical signs. Arabian horses in California on alfalfa hay are at risk of developing enteroliths, and this should be high on the list of differential diagnoses for such cases. Radiographs of the abdomen can be helpful, although the absence of supportive radiographic findings are not conclusive.

A foal or weanling that appears parasitized and has a history of recent worming or worming with ivermectin only could be at risk of having an ascarid impaction. All available evidence that supports a diagnosis of small intestinal obstruction should be sought in such cases (reflux, ultrasound examination). Although typically treated by surgery, medical treatment with laxatives should be worth trying.

Foals can have all the same surgical lesions as adults except for strangulating lipoma. Foals are notoriously difficult to assess because they can alternate between periods of violent colic and periods of depression. Inability to perform a rectal palpation in foals complicates their examination, although the ability to perform a more complete ultrasound and abdominal radiographic examination compensates for this.

Horses with proximal enteritis can have a fever and leukocytosis and a greater volume of gastric reflux than horses with other small intestinal diseases. Horses with proximal enteritis may have severe abdominal pain initially, and this progresses to depression and less pain than in horses with strangulation obstruction. After gastric decompression, horses with proximal enteritis usually improve in overall attitude and heart rate decreases, but this is not always reliable. On palpation per rectum, tightly distended loops are suggestive of strangulating lesions, whereas distension is milder in horses with proximal enteritis. [...]