Colic Inside and Out

Kerry Comb BVMS CertEP MRCVS
Julia Shrubb MA VetMB MRCVS
Ashbrook Equine Hospital, Cheshire

WHAT IS COLIC?

Colic is a broad term used to describe the symptoms of abdominal pain. It covers a wide range of conditions that cause ‘belly ache’, ranging from very mild to acutely life-threatening. In horses, colic most commonly involves the intestines. This article concentrates on this type of colic, but horses with many other problems such as liver or urinary problems can show colic signs.

The signs of colic are very variable. These include the obvious signs such as rolling, pawing, kicking at the belly and sweating. Other signs include looking at the flanks, lying down, dullness and standing as if to urinate. The horse may be reluctant to eat and may have passed fewer or no droppings.

HOW WE APPROACH THE COLIC CASE

Most colics require immediate veterinary attention. If your horse is showing very mild signs with a normal amount of droppings and you are not sure if a vet is required, we recommend removing all feed, walking the horse and reassessing after 20 minutes.

Whilst waiting for the vet to arrive you should remove all food. If there are mild signs, walking the horse can be beneficial. If the horse is very painful and is trying to roll, do not get hurt by trying to keep it up. Rolling does NOT cause the gut to twist.

Once the vet arrives, he or she will assess the severity of the condition to determine the best treatment plan. This will involve getting some background information about your horse, its usual management and further details about this and any previous colic episodes. An examination will then reveal important parameters including heart rate, breathing rate, mucous membrane colour, gut sounds, temperature and rectal examination. If the horse is very painful, a quick examination may be performed before giving painkillers and possibly sedation, so that a more thorough examination can be performed safely.

Heart rate is a very useful indicator in colic. A normal heart rate is between 30 and 40 beats per minute. This will go up with severe pain and serious colics often have significantly raised heart rates. The colour of the gums will be assessed and are normally pale pink and moist. Dryness indicates dehydration and dark colouring indicates toxins are being released from damaged intestine.

A stethoscope will be placed on the flanks in order to listen to the gut sounds. Often colicking horses have reduced, or even absent, gut sounds as the intestinal movement slows down. However, in spasmodic colic the gut sounds are usually increased.

A rectal examination is performed only when necessary as there is a small risk to both vet and horse. Rectal examination gives vital information about the location and size of intestines in the back 40% of the abdomen. Abnormal findings that may be detected include large colon that has moved into the wrong position (displaced), impactions (especially at the pelvic flexure) and abnormally distended small intestine.

In some cases, further diagnostic aids are very useful. A ‘belly tap’ may be performed, which is when a small amount of peritoneal fluid, that bathes the abdominal organs, is collected through a needle. This can be analysed and may indicate if there is any damaged gut. Bloods are also useful, particularly to assess hydration status. If the vet suspects a small intestinal problem, a stomach tube may be passed via the nose into the stomach. Horses cannot vomit, so if there is a small intestine problem, food and fluid builds up, filling the stomach. This only occurs if there is a serious problem with the small intestines. This fluid may need siphoning off to empty the stomach, temporarily making the horse more comfortable and reducing the risk of the stomach rupturing.

Abdominal ultrasound through the body wall can also be useful to visualise the intestines near to the body wall. This may give additional information about abnormal intestinal location, intestinal movement and any gut distension.

CAUSES AND TREATMENTS

Colic can be medical or surgical, medical is by far the most common. Colics can be very varied but the most commonly encountered are discussed further.

Medical – Spasmodic
– Impactions

Surgical – Small intestinal
– Large intestinal

Treatments range from spasmolytic and pain relieving injections to fluids, orally or intravenously, to surgery. Surgery is rarely necessary but decisions often need to be made quickly and under difficult circumstances.

Spasmodic or mild medical colic

Signs are usually of mild pain that can wax and wane. The causes are varied but often a change in management is implicated. An important point to note is that tapeworm infestation has been linked to spasmodic colic. These horses are usually treated with spasmolytic and pain relieving injections. Food is withheld for a couple of hours before gradual re-introduction of a normal diet. Walking the horse can help with return of normal intestinal function. Most horses make a rapid and full recovery after treatment. Occasional horses have a propensity to this type of colic and in these cases can sometimes be managed by the owner after discussion with the vet.

Impactions

These are usually due to build up of food material and therefore are often associated with diet changes or sudden enforced box rest. Dehydration can also play a part in initiating impactions. These can occur in the small or large intestine, the latter being much more common due to the anatomy of the pelvic flexure. At this point in the intestine, it turns 180°, narrows 50% and goes uphill – a design fault! These horses usually have mild-moderate but unrelenting pain and often decreased faecal output. Treatment involves pain relief and fluids. Large volumes of fluid are given by stomach tube, often in combination with liquid paraffin, to move the mass. On occasions intravenous fluids may be required. In the worst cases it can take up to seven days for the impaction to pass.

Surgical colic – small intestine

Small intestinal problems usually result in signs of extreme pain and toxicity. When examined per rectum the small intestine will be distended. The most common cause of small intestinal surgical problems are lipomas – small, fatty lumps often found on stalks in the abdomen. Lipomas are very common in ponies more than 12 years old and most never cause a problem. On occasion these lumps wrap themselves around the small intestine, trapping food material and preventing adequate blood supply to the intestine. If detected early, the lipoma is removed and the intestine remains healthy but often by the time the pony reaches a surgical facility the area of intestine is beyond salvage. The good news is that there is a lot more small intestine than is needed, so removing some of it has no long term implication for the pony.

Healthy small intestine on right, damaged on left after lipoma removal

Surgical colic – large intestine

The large intestine takes up most of the space in the abdomen and it is only fixed in one place so can become displaced or twisted. Providing there is no affect to the blood supply these horses often only show moderate signs of pain. Abnormal positioning can often be felt during a rectal examination. Some of these can be treated medically and some require surgery. If the malpositioning is so severe that the blood supply is disrupted, the horse becomes very painful. Due to the size of the large intestine a huge quantity of toxins are produced. Speed of diagnosis and effective treatment are essential in this instance as it does not take long for the affected gut to become damaged beyond repair. Removal of large intestine is much more complicated than of the small intestine and some areas cannot be removed.

PREVENTION

Many colics occur for no apparent reason. However there are certain common-sense measures that should be followed to minimise the risk of colic.

Ensure there is a regular feeding regime
Make management and feeding changes gradually
Switch between hay or haylage and poor or lush grazing gradually
Feed should be of good quality, with an adequate supply of forage
Remember horses are grazers; they should eat little and often
Straw can predispose to impaction colics, so if a horse gorges on its straw bed, consider using non-edible bedding such as shavings
Ensure there is always a supply of clean, fresh water
Daily turn out or exercise is beneficial, although it may not always be practical or possible
Regular dental care
Appropriate worm control (see below)

Worming is very important in preventing colic. Small redworm and tapeworm infection has been statistically proven to cause increased cases of colic. Worming protocols can be very confusing. It is important to worm for tapeworm at least once a year. A blood test is available which can be used to check the efficacy of your worming program or to see if worming for tapeworm is actually necessary. There are two approaches to controlling redworms; traditional or strategic worming. The traditional approach is to worm regularly with an appropriate wormer at the interval specified for that drug. Alternatively a faecal egg count can be performed to see if worming for redworms is actually necessary with the benefit that you only worm if necessary. This reduces the chance of resistance and saves money.

SUMMARY

Colic should not cause people to panic. The majority of colics resolve very quickly with medical treatment and do not recur.