Colic, Medical Treatment

Colic should always be viewed as an emergency as almost every colic case starts with a medical aspect. Over 90% of colics are medical and of these, the majority are associated with spasmodic intestinal colic. It can be difficult for veterianarians to distinguish between medical colic and an early surgical colic because the clinical signs are often very similar. It is often a lack of response to medical therapy that makes the decision. If referral is necessary then it should be done as soon as possible as a slow approach by the veterinarian will result in time delay and incorrect therapy and a poor outcome.

Medical colic is defined as colic that will respond to drug therapy and management alone. Once treated, cases of medical colic should not have any further complications that could have been avoided hd surgery been undertaken. Medical colic is a common condition in equine practice. It can be potentially life threatening so referral centres still play a role in the mnagement of medical coic. Some cases may also be contagious and/or zoonotic. The differentiation between medical and surgical colics is critical and can be acheived by a thorough clinical examination. There are important considerations to keep in mind when interpreting colic clinical signs. Some horses and especially donkeys and zebras, are very stoical in their nature and show only mild clinical signs, despite having a serious surgical condtion. Some horses have a low pain threshold and so may show severe, unrelenting signs of colic that are features of surgical colic cases. Medical causes of colic are often less painful than surgical causes. However, anterior enteritis can cause extreme pain, but can be managed medically with Metronidazole, penicillin, analgesia and repeated gastric decompression. Few medical cases have a complete abscence of borboygmi. The faecal output can also provide valuable information. Cases with diarhoea are often medical in nature and require medical management. Cases with a reduced faecal output for a couple of days usually have an impaction of the large colon. Very hard, mucous covered faeces indicate a reduced transit time through the small colon. This could be due to Grass Sickness.

Pain management is an important aspect of treating any colic patient, whether it be surgical or medical. There are two major types of pain; visceral pain and parietal pain. Visceral pain is associated with inflammation or distention of a viscus, tension on the mesentery or a reduction in the blood supply. It is an obvious pain and the horse will exhibit signs of abdominal discomfort. The pain is oftern persistent and the horse maybehave violently if the pain is severe. Severe, unrelenting pain despite the administration of analgesia is an indication for surgery. Spasmodic colic that responds to analgesia is most likely to me medical. Parietal pain is associated with inflammation of the serosal surfaces of the organs of the peritoneum and parietal peritoneum. This pain is less obvious and the horse may be immobile guard the abdomen. This type of pain features in cases with a ruptured viscus and secondary peritonitis.

The response to mild analgesia is ofteen used to determine the level of pain and decide whether the case is medical or surgical. Mild analgesics include phenylbutazone or hyoscine-n-butyl bromide (Buscopan). Cases that do not respond within 2 hours require reassessment and potentially referral. Stong analgesics such as flunixin should not be used until the diagnosis has been made as many early surgical cases can be misdiagnosed as medical colics.

Treatment for the colicking horse should include all of the following:

• Pain relief
• Stabilization of the cardiovascular and metabolic status
• Minimizing the effects of endotoxaemia
• Establishing a functional intestine

Therapies should include the following, where clinically indicated:

• Analgesia
• Fluid therapy
• Cardiovascular support
• Laxatives and cathartics
• Antiendotoxin therapy
• Treatment for ischaemia-reperfusion injury
• Antimicrobial therapy
• Nutritional support
• Surgical intervention

Analgesia

Analgesia can be accomplished by the use gastric dcompression and the administration of analgesics.

Nasogastric decompression

Some patients require an indwelling nasogastric tube and repeated refluxing every 2 hours to prevent gastric distension and possibly gastric rupture. Patients referred to a surgical facility will require an indwelling nasogastric tube whilst being transported.

Antiendotoxin Therapy

Polymyxin B

Nutrition

Management of medical colic should also inlude diet management. All food including hay and straw bedding should be withheld until the resolution of the condition. The normal diet can then be re-introduced slowly over 1-2 days beginning with a moist bran and alfalfa pellet mash, then grazing grass, followed by moist hay and finally grain. If the patient does not have continuous gastric reflux then ad lib water and a trace mineral salt lick should be provided. If there is any doubt regarding the diagnosis and exploratory surgery is a possibility then all food should be withheld during transport to the referral facility.

Surgical Intervention

The decision to treat the patient surgically or medically depends on a number of criteria. Most colic cases seen in first opinion practice are mild and respond well to medical management. A small proportion of cases will require surgery and a lack of response to medical therapy is often the deciding factor. Candidates who are dificult to categorise should be referred early as procrastination and time delay during transportation could worsen the prognosis of the patient. A ventral midline celiotomy is the surgical approach for most cases but specific treatments for specific disorders also apply.

Large colon impactions can be difficult to manage.Most cases will respond to aggressive medical treatment with analgesics, laxatives, oral and intravenous fluid therapy. Some may not respond to medical therapy and are secondary to another lesion, such as a concurrent large colon displacement or impaction of the right dorsal colon, which may only be resolved with surgery.