In my last piece, I looked at how the vet will examine a horse with colic. Following this, and using all the information from the history and workup, he or she has to decide if the colic is Medical or Surgical. The terms are more or less self-explanatory: a medical colic can be managed with drugs, while a surgical colic needs emergency surgery.
As a rule of thumb, 9/10 colics are medical, and can almost always be managed on the yard.
So, here are the common causes of colic that we see in the UK1 :
1) Spasmodic Colic. This is probably the commonest, and perhaps the least understood; I estimate about 80% of Medical colics are Spasmodic. Spasmodic colic can be caused by a stressful event, mild dehydration, or be genuinely idiopathic (i.e. we don’t know what causes it!). It can also be caused by severe tapeworm burdens. In a Spasmodic Colic, a section of the gut goes into a spasm, preventing anything from moving past it. It can be acutely painful, but usually responds really well to management with drugs. For any horse that has two or more bouts of spasmodic colic, I’d always recommend a tapeworm blood test to make sure it isn’t part of the problem!
2) Impaction Colic. This is more common in some management systems – it is pretty rare, for example, in horses who live on grass. In these cases, the food in the large intestine dries out a bit too much, and turns into a putty-like material. It then gets stuck, typically at one of the 180- degree turns in the Large Colon. It’s also strongly associated with moderate dehydration – as a horse gets dehydrated, he will move water out of the gut in order to keep up his circulating blood volume. This is a clever trick, meaning a horse can survive levels of dehydration that would kill a human. However, if the water isn’t replaced, and he’s been eating dry hay, his gut contents can become so dry they cause an impaction. This is why, many years ago, bran mash and Epsom salts were fed after hard work – both are good ways of rehydrating the colon and Caecum contents.
3) Gut displacements and entraptions. These are a bit of a mixture – some are medical, some are surgical, some look surgical but aren’t, and some can be fixed medically but keep coming back so surgery is eventually needed. What many people don’t realise is that the guts are in constant motion. Occasionally, a loop of intestine goes “wandering around” inside the abdomen, and gets stuck behind something else (for example, into a little gap between the spleen and the kidney). These can often only be diagnosed by rectal exam, and can feel really confusing, where nothing seems to be exactly where it should be! Each case has to be treated on its merits, and many can be resolved by lunging – presumably because jiggling everything around helps the intestines to fall back into their proper places! Personally, however, my inclination is generally to refer the horse as a possible surgical case, because it’s amazing how often a trip in the box fixes a displacement or entraption. Of course, if they can’t be rapidly resolved, they need to have surgery to put everything back, before any permanent damage is done.
4) Sand colic – I’ve only rarely seen these; they’re normally caused by the horse drinking from sandy water. Over time, sand builds up in the intestines, causing irritation and sometimes an impaction. Management usually revolves around maintaining gut motion with laxatives and pain relief; however, surgery is sometimes needed to evacuate the sand and debris from the gut.
5) Inflammatory diseases, e.g. peritonitis or anterior enteritis. I’m including these here because they’re not strictly surgical. However, they can be really hard to differentiate from surgical cases, and they’re usually only diagnosed after referral, with the advanced techniques available at a referral hospital.
6) Other medical causes, e.g. diarrhoea, or stomach ulcers, can also cause a “Medical” colic; however, these cases require the underlying disease to be treated, at which point the colic symptoms will resolve themselves.
Treatment for medical colics is focused around pain relief and maintaining hydration. Spasmodic colics especially respond very well to a mixture of hyoscine and a pain-killer, which relaxes the spasming gut segment, allowing normal gut movement to be re-established.
Using a painkiller (e.g. injectable bute) can also be a really useful diagnostic test for whether a horse needs surgery – one of the standard guidelines is that a horse with a heart rate over 60 beats per minutes, 30 minutes after intravenous bute, is usually a surgical case. The other painkiller (flunixin meglumine) is almost never used, unless surgery is definitely not an option. This is because it is too powerful! Even horses with dead bowel can look bright, healthy and well, until the flunixin wears off. At that point, they crash, and are often too far gone to be saved.
Equipment for the medical treatment of colic
For impactions, rehydrating the gut contents is vital, but pain relief is also really important. In these cases, Epsom salts and water by stomach tube are really useful. There is some controversy over the use of liquid paraffin in impaction colics. If the horse later has to go to surgery, the presence of liquid paraffin in the gut can cause major headaches for the surgeons; on the other hand, it can be a marvellous lubricant to help move things along. Personally, I tend to give any impaction colic a bucket by stomach tube containing a mixture of water, electrolytes and Epsom salts; and if I’m sure it’s not surgical, I’ll add in a litre or two of liquid paraffin as well. Liquid paraffin is horrible stuff to work with, and if all you’ve got to give it with is cold water, it’s not easy to mix in; I like to mix the water and electrolyte tablets or sachets together first in a bucket, then add the paraffin.
The tube is passed down the nose and (hopefully first time!) into the gullet (if it goes into the wind pipe, start again…), and down all the way into the stomach. To check it’s in the right place, I always feel for it passing down the throat, listen for air moving as the horse breathes, and then suck on it to see if I get lots of air back (means I’m in the airways) or nothing (means I’m in the gullet) or, worst of all, a mouthful of stomach contents. This means the tube is in the stomach, which is great, but it tastes truly vile! Once I’ve carried out all those tests, I’ll pour in a tiny amount of clean water, just to be sure – if the horse coughs, it means the tube is in the windpipe despite all my tests, but it’s not the disaster it would be if I’d poured in a couple of gallons of liquid…
To get this lot into a horse, some people use stirrup pumps – they’re a bit like bicycle pumps, and attach to the end of the stomach tube. This is used to pump fluid from the bucket down the tube – they’re great if you’ve got them, although you have to be careful not to overfill the stomach. However, most of us still use syphons and funnels. The tallest person present (usually me…) attaches a funnel to the top of the tube, then fills the funnel from the bucket. They then hold the funnel as high as they can, so the liquid runs down the tube into the horse’s stomach. You then repeat this until either the bucket is empty or the funnel stops running, which normally means the stomach is full. It’s messy, and can be physically pretty hard work, but it’s a vital part of treating an impaction colic. Personally, I quite often use it to rehydrate the gut of any severe medical colic, because anything that causes gut stasis can lead to a secondary impaction if you’re not careful.
I’d normally treat a definitely diagnosed impaction with injectable bute for pain relief. There is some evidence to suggest that the use of anti-spasm drugs like Buscopan can help to encourage normal gut action, even though they are designed to work as gut relaxants, but I think that particular debate is still open.
To maintain hydration, some vets also like to start a drip line for intravenous fluids. This won’t help the gut (any excess fluid will be excreted by the kidneys before it gets there), but it can help to support the circulation of the horse. Personally, my thinking is that most colics that are so severely dehydrated that they need a drip are either surgical or have another, underlying disease; however, there are always exceptions!
Chronic, ongoing colics can be a nightmare to manage – they’re typically low grade, spasmodic colics, or mild impactions. In these cases, a more thorough examination (including blood tests) is indicated, to try and rule out any underlying disease. Chronic impaction problems tend to be management related, and can usually be resolved with minor tweaks to management. However, your vet will often want to check your horse’s teeth – this is because dental problems can result in poorly chewed food, which can make impactions more likely.
My experience with the chronic spasmodic colics is that if there’s no other underlying cause found, they can occasionally respond nicely to a course of probiotics. I had an incredibly frustrating case once of a horse that had repeated bouts of colic, that we never got to the bottom of. I was being called out every few weeks (and the yard was nearly thirty miles from the practice, which made each visit something of a nightmare!). Eventually I suggested we try a month’s course of probiotics… and the next time I saw the horse was nine months later for annual vaccination. Any further colic episodes, I asked? No, they replied – nothing since we started the probiotics. Although it isn’t a cure-all, it can apparently help in some cases!
Of course, not all colics are medical – about 10% require surgical management. In the third and final piece of this series, I will look at the indications for surgery, the types of colic needing surgery, and then I’ll go through what happens when your horse is referred to an equine hospital for emergency surgery.
1 This is based on my clinical experience in the Midlands, Wales and the South West of England. In some parts of the country, other causes will be more common – for example, on the South Coast, Sand Colic is more common. However, it seems to be fairly rare in most areas, so I’m not going to cover it in great detail.
If you are worried your horse or pony may be suffering from colic, talk to your vet, or check the symptoms using our Interactive Equine Symptom Guide to help assess how urgent the problem may be.