Colic, Decision Making

Once the veterinarian has carried out the examination, a decision as to whether the horse is a candidate for medical treatment or referral to a surgical facility for exploration, has to be made. Some cases will be difficult to diagnose and pose a problem to the decision to refer the horse. It is better for the veterinarian to refer the horse if there is any doubt as any further delay can make the difference between a sucessful and fatal outcome. The decision is based on a number of parameters listed below.

Parameters to Assist the Decision to Treat Medically or Surgically

• Pain
• Cardiovascular status
• Response to analgesia
• Response to medical therapy
• Rectal examination findings
• Quantity of garstric reflux
• Abdominal distension
• Abdominal auscultation
• Abdominocentesis results
• Ultrasonogaphic findings

These parameters will need to be reassessed over time to monitor for any change in the horse's condition and response to any therapy. A change in one or more of these parameters may be sufficient for referral to a surgical facility. The clinical signs as a result of pain and the response to analgesia are very important in assessing the need for surgery. Horse's with unrelenting pain that is not responsive to analgesia should be refered immediately. Rectal examinations are very useful in evaluating the colic patient as some surgical abnormalities of the gastrointestinal tract can be palpated.

The difficulty lies in the fact that signs of most medical colics are indistinguishable from the early signs of surgical colic. Almost all colics have a medical aspect at the start of the disease course. An early diagnosis and the appropriate treatment are necessary to cure the condition. It is also important to rule out conditions that mimic colic but do not involve the gasrointestinal tract. These conditions are collectively known as false colic. Other abdominal and major organs can cause pain that mimics intestinal pain. There may also be several sites involved that manifest in a common pathway of abdominal discomfort. The veterinarian must observe the whole horse and take into account any concurrent disease that can affect the clinical examination.

Is it Medical or Surgical?

Parameter	For continuing medical treatment	Immediate surgery/euthanasia
Pain	Mild to moderate pain	Severe unrelenting pain
Response to analgesia	Good response to mild analgesics	No response or short-term response
Cardiovascular Status	Pulse < 60 bpm, Normal CRT and mucous membrane colour, PCV < 40, TPP lowered	Pulse > 60 bpm and rising, CRT prolonded, Mucous membranes injected or cyanotic despite fluid therapy, PCV > 40, TPP rising
Response to medical therapy	Positive response and improvement in cardiovascular status	No response and progressive cardiovascular collapse
Rectal Examination Findings	Negative rectal findings	Positive rectal findings indicative of acute abdominal disease
Abdominal Distension	No abdominal distension or resolving	Increasing distesion
Abdominal Auscultation	Continuous or revived intestinal motility	Progressive reduction in intestinal motiltiy to complete abscence of borborygmi
Quantity of Gastric Reflux	Less than 2 L or none at all	More than 2 L, continued reflux of alkaline, bile stained fluid
Ultrasonographic Findings	Normal examination	Abnormal examination
Abdominocentesis results	Negative results, straw-coloured fluid, TPP < 25 g/l, WBC < 10,000 WBC/ul	Positive results, serosanguinous fluid, TPP > 25 g/l, WBC's increased

References

• Edwards B. (2009), Diagnosis and Pathophysiology of Intestinal Obstruction, in Equine Gastroenterology courtesy of the University of Liverpool, pp 9 - 10
• Knottenbelt D. C. (2009), Diagnosis and Management of Medical Colic, in Equine Gastroenterology courtesy of the University of Liverpool, pp 19 - 20
• Meuller E, Moore J. N. (2008) Classification and Pathophysiology of Colic, Gastrointestinal Emergencies and Other Causes of Colic, in Equine Emergencies- Treatments and Procedures, 3rd Edition, Eds Orsini J. A, Divers T.J, Saunders Elsevier, pp 112