Colic – Part 3: diagnosis and treatment

Welcome back to the third and final instalment in our series of articles on colic!  If you missed the first two parts, you may wish to check these out first, where we discussed clinical signs, initial action to take, the anatomy of the gastrointestinal tract and where it can go wrong.  Here we will look at how your vet may go about making a diagnosis and what treatment is possible.

What will be the most important parts of the veterinary examination?

• Assessment of pain level: vets tend to categorise colic pain as mild, moderate or severe, and recurrent or persistent. Generally, very severe pain, especially where the horse has self-traumatised itself resulting in bruising/swelling around the head and hips, indicates a serious colic which may require quick referral to a hospital, or occasionally, immediate euthanasia on humane grounds.
• Measurement of the heart rate and respiratory rates: these can help to indicate the severity of colic when used in conjunction with other clinical signs. It has been shown that horses which require surgery have the best outcomes when the heart rate is not much higher than normal (i.e. early in the disease process).
• Listening to the gut sounds: remember that the large colon is a series of big sacs which turn over the gut contents almost continuously, so there should always be lots of gurgling coming from the abdomen when listening with a stethoscope – some of this you may hear just with your ear. Quiet guts usually just indicate an impaction, but they also occur in serious colics, so us vets are always relieved when good gut sounds return!
• Temperature: this is normal in most cases of colic. If high, it might indicate peritonitis (infection in the abdomen) or a completely different problem masquerading as colic. If low, it is probably just an inaccurate reading, but it can also be low in very unwell horses in the end stages of a serious colic.
• Mucous membranes: the colour of the gums can be a useful indicator for your vet to assess. They are usually pale pink in horses (much paler than in humans or dogs).

What additional procedures might my vet undertake?

• Rectal examination: your vet will probably be keen to have a feel inside your horse’s abdomen as invaluable information can be obtained. However, this will only be possible if your vet deems it safe for them and the patient.  If the patient is too small or too nervous it may not be realistic.  Usually, an injection is given to relax the rectum and a tail bandage applied, both of which reduce the risk of rectal tears, which can be fatal.  This risk can never be completely removed but the benefit of performing a rectal examination usually outweighs the risk.  Clearly, your vet will be standing in a very vulnerable position so will probably need to take measures to reduce the risk of a dangerous kick, such as sedation, lifting a front leg, a nose twitch or standing behind a low stable door.
• Nasogastric intubation (stomach tubing): your vet may wish to pass a soft rubber tube up the nose and into the oesophagus and then the stomach, to see if there is excessive fluid backing up.
• Abdominocentesis (belly tap): occasionally, it is useful to take a sample of peritoneal fluid from the underside of the belly using a needle. Your vet will assess the colour of this and may submit it to a laboratory to check protein and white blood cell levels.
• Ultrasonography: if an ultrasound scanner is available, your vet may wish to scan the abdomen to assess the position and condition of the gut. It is only possible to see parts which are relatively close to the skin because the abdomen of the horse is so big.
• Blood samples: sometimes a blood sample may be useful to check hydration, electrolyte and blood cell levels.

Although all of the above investigations can be useful, in practice the most important ‘test’ is to observe how well the patient responds to painkillers.  Unrelenting or recurrent pain, despite appropriate medication, is always a worry and should not be ignored.

What treatment might be suggested?

Let’s start with a reassuring message – a significant proportion of colic cases have resolved before the vet even arrives.  Your vet will want to give the horse a check over anyway, as in some conditions, pain can be intermittent.

Injectable medications: in most cases of colic, painkillers such as flunixin or bute will be appropriate.  Anti-spasmodics are also commonly used, including before a rectal examination.  Opiods, such as morphine, can be administered in moderate/severe pain.  Sedation may also be necessary to relieve suffering or to make additional investigations safer for all concerned.  Some of these drugs may be used ‘off- licence’, ie not for their original intended purpose.

Withholding of food: it is usually sensible to give the gastrointestinal system a reduced payload for a few hours, or longer in some conditions.

Exercise: some small intestinal entrapments or large colon displacements will flip back into their normal position with a bit of gentle jiggling around, such as lunging at trot or a trailer ride.  Impactions can sometimes be encouraged to move with gentle walking exercise.

Fluids: pelvic flexure impactions are usually treated with several litres of dilute magnesium sulphate (Epsom salt) solution to draw fluid into the gut and soak the impaction.  Most horses won’t drink this (you know the old adage ‘you can lead a horse to water ….!’) so nasogastric intubation (stomach tubing) is employed.  If your vet agrees, you may wish to offer warm plain water with an additional bucket of a palatable electrolyte solution in an attempt to encourage drinking, which can be useful in numerous types of colic cases.

Surgery: only about 5-10% of colic cases require abdominal surgery, but it is really important for your vet to be given the opportunity to spot these cases at an early stage, because the chances of survival and full recovery are largely dependent on the speed of referral to a clinic or hospital which can carry out this procedure and give the intensive care required.  No hospital will ever complain that they have received a patient who does not require surgery so don’t be shy to discuss referral if your vet thinks this should be considered.  Of course, there will be times where surgery is inappropriate or unavailable.  Factors to consider might include age, general health, temperament of horse, finances available, clinical prognosis and geographical location.  A veterinary bill for colic surgery will be several thousand pounds at least and several months of confinement with a gradual return to turnout and exercise will be essential.

Euthanasia: very sadly, some patients will be found in the end-stages of colic and the only appropriate course of action to relieve suffering is to put the horse to sleep.  If a condition will only resolve with surgery, and this is not possible for any reason, euthanasia will also be necessary.

Take Home Messages:

• Call your vet as soon as you suspect colic and discuss whether a visit would be advisable
• Be prepared to monitor your horse regularly whether a visit is required or not
• Discuss with your vet whether the condition causing the colic is likely to resolve with medical or surgical treatment
• Try to make changes in feeding and management gradually
• Employ a vet or qualified dentist to look after your horse’s teeth annually
• Consider in advance if you would be prepared to consider authorising colic surgery, should this become necessary