What is colic and how does it affect horses?

Colic is a general term for abdominal pain in horses. There are many different causes of colic, most of them related to the gastrointestinal (GI) tract, although there are non-GI causes of colic.

Colic is the most common emergency in adult horses and is the leading cause of death in adult (non-geriatric) horses. Therefore, it is typically treated as an emergency by both owners and veterinarians. You should consult your primary care veterinarian for any horse suspected to be experiencing colic. About 1 in 10 horses may require emergent surgical intervention to resolve the cause of the colic.

Why do horses get colic?

Horses are at a high risk of colic due to their specialized gastrointestinal tract. The equine GI tract undergoes several regions of narrowing and dilation. This means that there are areas where feed can cause an impaction or obstruction. They digest the hay and grass they eat in the large intestine of their lower GI tract (or hind gut). Horses are dependent on normal gut bacteria for fermentation and digestion, which makes their GI tract sensitive to changes in diet or administration of drugs (such as antibiotics). Finally, there are few primary attachments of the intestine to the body and these are in same place where the blood vessels supply blood to the intestines.  This means that several parts of the equine GI tract are highly mobile since there aren’t a lot of attachments, resulting in an increased risk for displaced or twisted intestine. Twists (volvulus) can lead to a loss of blood flow to the affected segment of intestine.

Different types of colic

 Different types of colic can be more or less common based on your horse's age, breed, and diet, as well as geographic location. Colic due to problems in the GI tract can be divided into two major categories:

1. Upper GI (including stomach and small intestine).
2. Lower GI (cecum, large colon, and small colon).
   

Common diseases affecting the upper GI tract include:

• Gastric ulcers (stomach ulcers).
• Ileal impaction (small intestinal impaction) – This occurs more often with coastal hay.
• Small intestinal strangulation – This is often due to a lipoma (a kind of benign fatty tumor) which grows on a long mobile stalk. The stalk then can wrap around part of the small intestine, cutting off the blood supply.
• Enteritis (inflammation of the small intestine).
  

Common diseases affecting the lower GI tract include:

• Gas or spasmodic colic – Buildup of intestinal gas, cramps or spasms.
• Large colon impaction – This occurs when the feed gets too dry in the colon and is sometimes due to not drinking enough water.
• Sand colic – This occurs when the horse ingests a large volume of sand or gravel which can irritate the lining of the colon or cause an impaction.
• Enterolith (stone) – This is an accumulation of minerals into a stone-like substance and is more common in some regions of the US and in horses on alfalfa hay.
• Large colon displacement – This occurs when the large colon moves out of its normal position.
• Large colon volvulus – This occurs when the large colon twists, resulting in a loss of blood supply to the large colon.
• Colitis (inflammation of the large colon).
  

What are the signs of colic?

Horses may display a wide variety of clinical signs that indicate colic. Common signs include:

• Laying down more often or getting up and down frequently
• Pawing
• Rolling
• Sweating
• Flank watching (looking at the abdomen)
• Flehmen response (curling the upper lip)
• Standing stretched out as if to urinate
• Lethargy- tiredness
• Decreased interest in eating or drinking

What to do if you notice that your horse is colicking?

If you are concerned that your horse is colicking, this warrants a prompt call to your primary care veterinarian. A physical examination will help determine if your horse is sick, dehydrated, or has a high heart rate – all of which are concerning findings that may warrant additional treatment or referral to a Large Animal Internal Medicine Specialist. Veterinarians will often then perform the following diagnostics listed below, which may be followed by additional tests as recommended by your veterinarian.

• Passage of a nasogastric tube (tube inserted through the nose down to the stomach): Horses are unable to vomit. Therefore, if there is excess fluid in the stomach (also known as reflux), it must be removed by nasogastric intubation, or a tube inserted through the nose. The presence or absence of reflux can help your veterinarian figure out the kind of colic your horse may have. If there is no excess fluid in the stomach, then your veterinarian may put water and/or other therapies into the stomach using the tube.  
• Rectal palpation of the abdomen (insertion of a gloved hand and arm into the rectum): Rectal palpation can be helpful in identifying common problems such as small intestinal distension, large colon impactions, or large colon displacements/torsion (twisting). Due to the size of the horse's abdomen, a substantial amount of intestine is not palpable, or out of reach to the hand.
• Additional tests that may be recommended: Further diagnostic tests that may be used include bloodwork, abdominal ultrasound, and sampling abdominal fluid ("belly tap" or abdominocentesis).

After assessment of your horse, your veterinarian will have recommendations for you. If the colic is severe, your horse is systemically ill, or the veterinarian suspects a surgical lesion is the cause, your veterinarian may recommend referral to an equine medical and surgical center with specialists.

How is colic treated?

Most cases of colic can be treated simply, with nasogastric intubation to deliver water to the GI tract, and a single dose of a Non-Steroidal Anti-Inflammatory Drug (NSAID), such as flunixin meglumine (Banamine), to relieve pain. Please consult with your veterinarian BEFORE giving any medication to your horse. Never give flunixin meglumine (Banamine) in the muscle.

Your veterinarian may also likely recommend restricting your horse's access to feed until the colic has fully resolved, then gradually refeeding with increasing amounts of food over the next 1-2 days.  During this time, monitor your horse closely for passage of normal manure, and any return of colic signs. It is important to always allow free access to fresh water unless otherwise directed by your veterinarian.

Some colic types require prompt medical or surgical intervention provided by veterinary specialists. Ideally, you should have a pre-determined plan for transportation of your horse should it be necessary prior to any episode of colic. Your primary care veterinarian can help you develop this plan.  

What is the prognosis for a horse with colic?

The prognosis for a horse with colic heavily depends on the cause of the colic. Many colic episodes are due to gas/spasmodic colic or a mild impaction of the large colon – both of these types of colic typically respond readily to medical management. Other causes of colic which cause the horse to be systemically ill or result in loss of blood flow to the intestines have a poorer prognosis, although the ability to pursue intensive care or colic surgery can significantly improve the outcome.

The prognosis with those interventions depends on the specific type of colic treated and how sick your horse is. Many horses can return to athletic function after colic surgery. Your veterinarian and/or Large Animal Internal Medicine specialist can give you further information on complications and prognosis for your horse