EQUINE: WINTER COLIC – SAFEGUARDING DIGESTIVE HEALTH
22 Nov 2018
One of the most common winter time health problems in equines is colic. Colic is basically gut pain, and can be very distressing for both horse and owner. The main problem with colic is that, in the early stages, it is impossible to distinguish a mild attack from a potentially fatal one and therefore all cases of colic should be taken seriously. There are steps that we can all take to try to minimise the risk of colic in the equine population.
The design of the horse’s gut is such that it predisposes the horse to colic. The small intestine (SI) is 22 metres long and 7-10cm in diameter. A curtain-like layer of thin skin (called the mesentery) holds the SI in place along its entire length but is attached to the abdominal wall at only one point in the middle of the abdomen. This lack of rigidity means that the SI is very prone to gut displacements and torsions (twisted gut). In between the SI and Large Intestine (LI) is the caecum; a large, blind-ended pouch where much of the gut fermentation takes place. The LI itself is 3-4 metres long and 20-25cm in diameter and is attached to the body at only two points (the beginning and the end). The LI is arranged in the intestinal cavity in two, big U-shaped loops and within this there are hundreds of flexures (bends). It has been calculated that as food passes down the horses gut it goes around 180 bends. This means that not only is there a risk of the gut twisting but there is also a high likelihood of a blockage occurring because of all these flexures. Add to this the fact that the horse’s digestive process relies on fermentation, which produces gas and it is hardly surprising that the majority of horses experience colic at some point in their lives.
Unfortunately if your horse has had colic before, he is at a high risk of a recurrence. In a study looking at colic cases and their possible causes, 43% of horses with colic had previously experienced a colic attack. It is also thought that 50% of colic cases are related to diet management. They are also at a higher risk if fed a high proportion of concentrate or are on restricted turn-out.
There are a few factors which contribute heavily to the increased incidence of colic during the winter time; 1. Horses drink less water, either because they are not as thirsty or because their water supply has frozen up (in the field or stable). Hay and haylage is only approximately 10-40% moisture compared to the 75% moisture contained in spring and summer grass. With this decrease in moisture intake the processed feed is too dry to move along the digestive tract and problems with impaction can occur. This problem usually builds up over a period of weeks and there may be early warning signs; less or very dry droppings or reduced water intake. 2. When the colder weather comes the inclination may be to increase the hard feed portion of the ration. This is likely to upset the digestive processes. 3. Decreased turn-out time or no turn out reduces activity. Inactivity may slow the movement of food through the digestive tract. 4. Sudden changes to exercise or feeding routines can also cause digestive upset.
All or some of these factors can be the trigger for a colic attack during the winter months, so what can we do to limit the risk?
The causes of colic are multifactorial and there is no single thing that can be done to prevent it, but there are things we can do to limit the risk. 1 WATER – Make sure that water is fresh and not frozen all day, also check that the footing to the water trough is ok. Some horses will not drink really cold water so offer them a bucket of water that has been warmed. This is easily done with a kettle or thermos of boiled water added to a bucket. This trick will also lower the chance of water buckets in stables from freezing. Feed salt to encourage water intake. 2 ROUTINE – make sure that you have a feeding routine and stick to it as much as practically possible. Make any changes gradually. Especially be aware of swapping from hay to haylage (and vice versa) and make sure that this is done very slowly and with great care. As far as the bugs in the horse’s gut are concerned there is a very big difference between hay and haylage and many an upset stomach has been caused by a rapid swap. 3 ROUGHAGE – feed mainly fibre (hay, chaff, sugarbeet etc), only feed cereals if absolutely necessary and try to use high oil products (or oil itself) as an energy source as much as possible. 4 FEED LITTLE AND OFTEN- Try to spread your horse’s daily ration over as many feeds as practically possible. This is particularly important if they need a lot of hard feed. Remember the horse’s stomach is only the size of a rugby ball and no more than 2kg of concentrate should be fed per meal (preferably less). 5 WORMING – make sure you have an effective program in place. Especially make sure that your horse is wormed against small encysted red worms in December/January. Unfortunately these do not show up in worm egg counts so should be part of a strategic/targeted worming schedule. Dung samples can be sent off for worm egg counts to check if your horse’s need a routine wormer. Speak to your vet or local animal health shop SQP (suitably qualified person) about a good worming regime.
There are many other causes of colic that we do not fully understand but if attention is paid to the above areas then the risk of a colic episode should be greatly reduced.
By DR VICKI GLASGOW