Veterinary column
Coping with Colic
1st October 2009
Veterinary Column by David Bardell MRCVS
Colic is a common problem in horses. Although it is difficult to be precise about how common, every year between 3 and 10 horses out of every 100 will suffer an episode of colic. Approximately 8% of these (between 2 and 8 horses per thousand) require surgery to try and resolve the problem. There are many factors which contribute to the risk and incidence varies between countries, regions within a country, type of horse, level of work the horse is required to do, as well as feeding and management regimes.
Colic means abdominal pain, usually originating from the digestive system. This simple term encompasses a wide range of gastrointestinal problems including simple gas distension, mild impactions of food material, displacements of parts of the gut into abnormal positions, inflammatory conditions, generalised motility dysfunction and strangulating lesions where the gut becomes twisted or trapped, so cutting off its blood supply. At best, colic is uncomfortable for the horse and worrying for the owner; at worst, it can cause the horse extreme pain and ultimately be fatal.
Early recognition of signs indicating colic and prompt veterinary involvement is critical. The earlier the horse can be treated and appropriate decisions made about how to manage it, the better. Prompt identification and referral of those needing surgery will generally improve the chance of a successful outcome. Whilst success rates for colic surgeries have improved dramatically over the past 20 years, surgery still carries considerable risk to the horse, is expensive and requires a prolonged period of convalescence. A lot of research is focussed on identifying risk factors which predispose to colic, as well as developing more successful treatment methods and monitoring outcomes. One of the frustrating aspects is that in the majority of cases a definitive diagnosis is never reached.
Signs of colic may be subtle such as the horse being off its food, mild pawing at its bedding, turning its head towards its flanks or just lying down more than is normal. Food, but not water should be removed if you suspect your horse is suffering from colic. It is not unusual for pain to be intermittent and in the periods when the horse feels more comfortable it may want to eat which can possibly make the problem worse. The greater the degree of discomfort the more marked the signs will become and individuals may sweat, box walk, repeatedly lie down and stand up, roll and look markedly agitated. Some may show violent signs and kick, bite or throw themselves around inflicting cuts and bruises on themselves and becoming dangerous to handle.
Your vet may need to administer pain killing or sedative drugs in order to be able to examine the horse properly and will conduct as thorough examination as possible. It is usual to take heart and respiratory rates, look at colour of the gums, feel the pulse and listen for gut noises. More invasive examinations may be required such as taking blood samples, passing a tube into the stomach to see if there is a build up of fluid and gas, performing a rectal examination to detect distended or displaced sections of gut or taking a sample of fluid from the abdomen by placing a needle through the body wall under the belly of the horse.
These tests will allow your vet to determine how severe the problem is, what the most appropriate treatment will be, monitor response to treatment or note any deterioration. A decision can then be made whether the horse can be managed at home or requires referral for more specialist treatment. In considering referring the horse an important factor is whether it is safe or humane for the horse to be transported and unfortunately there are a small number of horses which will require immediate euthanasia as it is impossible to control their pain. It is inhumane to transport a very painful animal and if it becomes violently painful during transport an extremely dangerous situation can rapidly arise. If your vet has concerns, he may well advise transporting the horse whilst it is safe to do so. Although this may ultimately prove to have been unnecessary it is far preferable to waiting and then being unable to take the horse somewhere it can receive the treatment that it needs.
Approximately 75% of all colics are mild and will resolve rapidly after administration of drugs which relieve discomfort and reduce gut spasm. Making the horse comfortable allows or encourages normal gut motility to return which promotes gas expulsion or breakdown of mild impactions. Gentle exercise such as walking the horse or lunging can sometimes help. More extensive or solid impactions may require fluids to be administered (either by stomach tube or intravenously) to soften the mass so it can start to move. Some displacements may resolve spontaneously if normal motility patterns return. There are certain types of colic which are associated more with different ages and types of horse. Older animals frequently develop fatty lumps within their abdomen which can wrap around a section of intestine and cause a strangulating problem, recently foaled mares may develop displacements and twists of their large colon, whilst foals may be more likely to suffer from intussusceptions (a condition where part of the gut telescopes inside itself and becomes stuck).
The digestive system of the horse is classified as a hind gut fermentation system. This relies on a population of micro-organisms within the large intestine to ferment and break down dietary fibre into products which can then be absorbed and utilised. This system is functionally similar to that of elephants, rabbits and guinea pigs and very different to our gut as well as that of other familiar grazing species such as cattle, sheep and deer. In evolutionary terms this design has developed in response to extended periods spent grazing poor quality, fibrous grasses.
This is obviously very different from the way that horses and ponies are generally managed and fed today. The more work and athletic activity that is required of a horse, the more the dietary balance swings from forage and grazing to compounded feedstuffs containing not only higher levels of energy, but energy provided in a different form. Diets which contain a lot of rapidly fermented carbohydrates (simple sugars and starches) such as those found in cereals require more digestion to occur in the small intestine. This causes the fermentation process and microbial balance in the large intestine to change, a more acidic environment is created and damage to the gut wall can occur, increasing the likelihood of absorbing toxins. Normal propulsive gut motility may then be affected, as may the ability to adequately digest fibre, allowing gas or food material to build up. The gut has some ability to adapt to dietary changes, so addition of new feeding stuffs, or increasing amounts of concentrate feeds should be done slowly to allow this to occur.
It is important that adequate amounts of fibre are provided as this is the most natural substrate for the equine gut to process. This can either be by access to grazing which has been shown to reduce the risks of several types of colic occurring, or providing conserved forage (hay or haylage) if grazing is limited. Feeding guidelines for conserved forage tend to recommend that a minimum of 1-1.5% of a horse’s bodyweight should be provided per day. It is important to be aware that starch content of grass can change rapidly (depending on temperature and amount of sunlight). The composition of grasses in different paddocks may be very different and quality and composition of different batches of hay and haylage can vary considerably. Changes in forage and grazing have been shown to increase the risk of colic developing for up to two weeks after the change has occurred. This effect can be as significant as sudden changes in compound feeds although may take longer to become apparent. Changes should again be made slowly, and extended access, allowing horses to ‘trickle feed’ is better than intermittent access to large quantities.
Colic generally shows a seasonal variation with more cases reported in the spring and autumn months. Alterations in housing and turn-out periods, changes in feeding and in grass quality may contribute to this. Increased periods of stabling may predispose to the development of stereotypic behaviours such as crib biting and windsucking, both of which have been associated with an increased risk of developing certain types of colic. Whilst increased periods at pasture has generally been shown to reduce the risk of colic, care should be taken in spring as lush grass can contribute not only to colic, but to development of laminitis.
Regular dental care to enable the horse to chew its food properly is also important as dental disease has been linked with colic, particularly in donkeys. The risk of dental problems increases with the age of the animal. Fortunately many horse owners are aware of the benefits of regular dental care and this is one area which has seen a big improvement in recent years.
Another area which has seen considerable improvement is parasite related colic. Heavy infestations of large roundworms (ascarids) can physically obstruct the gut, small redworm (cyathostome) and tapeworm infestations have also been linked to increased risk of colic. With the increased awareness of good worming programs, these are fortunately rarely seen now.
It can be appreciated that colic is a term encompassing a wide range and severity of problems. Whilst it is not possible to completely remove the risk of a horse developing colic, there are a number of ways in which the risk can be reduced.
Keeping feeding and management practices as natural as possible combined with regular worming and dental care are reasonable rules to keep in mind. Make any changes gradually if introducing new feeds, increasing amounts, buying different forages or changing grazing and keep feeding routines as regular as possible. Frequent, small feeds are better than fewer, larger feeds. If in any doubt always consult your vet.
The photos below illustrate points from this article:
1. Very large, infrequent feeds can contribute to the risk of colic. The digestive system of the horse is better able to copy with small, frequent meals and any changes should be done gradually.
2. Unusual disruption to the bedding in your`s horse`s stable may indicate that there has been an episode of colic. This horse was displaying signs of mild colic by pawing at the bedding. There is also an absence of droppings in the stable which may be another indicator that all is not well.
3. Colic surgery is a complex and difficult procedure that requires specialist knowledge and facilities, and involves a large number of people. The earlier the need for surgery is recognised, generally the more likely it is to have a successful outcome, although it will always present a risk to the horse.
