How to control pain in horses [H&H VIP]

  • Keeping a horse comfortable through illness or injury means judging just how much pain he is in. Karen Coumbe MRCVS discusses how to assess this and the challenges of selecting the right painkillers

    Equine pain control has improved during the many years I have been a vet, but there is always room for further improvement.

    It is generally now understood that struggling with a patient who is in pain or relying on a twitch is unlikely to be successful and that better methods of care are usually available.

    Readers of the Veterinary Record recently voted anaesthesia and analgesia (pain control) as the biggest developments in veterinary medicine during the 125 years since the journal was launched.

    Certainly, the ability to provide more effective anaesthesia and pain relief has made a big difference to equine health and welfare. There are now better medications available and more understanding of pain, which means vets can perform far more complex surgical procedures than was previously possible.

    Successful colic surgery, for example, has become an increasingly routine procedure for most major equine hospitals.

    Complex orthopaedic techniques, as well as airway surgery, are now possible. There has been massive progress in the past 25 years — probably nearly as much as in the 100 years before that.

    Handle with care

    Effective sedation has made a considerable impact on the efficient management of horses in discomfort or difficulty.

    Modern sedatives usually include a painkiller in the medication that is injected by the vet into a vein. This then allows a variety of procedures to be carried out calmly, ensuring the safety of all concerned. The horse can remain standing calmly during lengthy MRI exams, for example, or laparoscopy (using a small telescope to look inside the abdomen).

    Similar approaches are being used for standing surgery on teeth, sinuses and kissing spines. Some fractures can even be repaired using local anaesthetic, appropriate strong sedation and plenty of painkillers.

    Dr Polly Taylor MRCVS, the anaesthesia specialist who reviewed the innovations for the Veterinary Record, described an important mood change among vets. Once thought “only for sissies”, sedation is now widely regarded as an essential.

    Still, these medicines should never be misused and horses must always be handled with care. If a sedative is given without pain relief, the horse could still be in pain but may be too drowsy to object. The reality is that most will remain sufficiently aware to react — as those who have been kicked by an apparently sedated horse can testify.

    We must remember that horses do not have the brainpower for reasoning. They will react to pain by instinct, responding by “fight or flight”. This can result in injury to either the horse or handlers.

    Behavioural clues

    Being aware of a horse’s normal behaviour patterns makes it easier to identify changes. This means observing and understanding his actions without attributing any human feelings.

    Could he have a headache, or something else that you cannot see? Watch out for any variation from normal. This may include signs such as a horse taking no interest in his surroundings, or standing quietly at the back of his stable or away from the rest of the herd.

    Horses do not show pain in the same way as people. They can be very stoical, with some breeds and types, such as cobs, being particularly tough. Foals are often sensitive souls who let you know when something is wrong, but older horses can give very few clues that they are uncomfortable.

    As they are prey animals, horses are programmed not to display behaviour that will make them vulnerable to attack by predators. Subtle signs of discomfort or distress can easily be overlooked.

    Nursing the patient

    It is usually clear when a horse has severe colic pain or is hopping lame, but discomfort is not always taken as seriously as it should be.

    According to a study published in 2005, only 37% of vets gave painkillers following colt castration. We have moved on and equine patients these days are better protected from the pain of surgery, but the subject still needs proper consideration. Always ask yourself what is reasonable treatment for your horse.

    There is an enormous amount that can be done to control pain, ranging from basic bute to potent painkillers such as morphine and newer morphine-like drugs now licensed for the horse in the UK.

    Side effects and the risk of masking clinical signs are often used as excuses to avoid the use of painkillers, but pain itself produces problems. Both equine and human patients heal quicker when feeling comfortable.

    Painkillers can be administered in different ways. Some sophisticated mixtures are available as a drip, while high-tech epidurals are particularly good for chronic debilitating lameness.

    The correct timing of administration is crucial. Pre-emptive analgesia is effective, where painkillers are administered before a pain-producing event — such as a “pre-med” prior to surgery.

    Side effects can be minimised by multimodal treatment, where the combined administration of different painkilling techniques reduces the overall concentration of drugs given.

    There are many occasions when pain-killing medication is not the only answer. A comfortable bed, a warm rug and a decent support bandage can help, as can appropriate complementary therapies such as physio, chiropractic and acupuncture.

    Never underestimate the importance of good nursing and nutrition. Offering your horse tempting feeds, keeping his haynet full and treating him with kindness will all aid a good outcome.

    The horse grimace scale

    Doctors and nurses use pain scales to assess their human patients, often just asking how sore a person feels on a scale of one to 10. But it is not so simple with horses.

    One team of European researchers has just reported on a study where they watched videos of 46 stallions before and after surgical castration. Some of the horses had been given painkillers and some had not.

    In nearly 75% of cases, the effect of pain could be determined by looking at the animal’s facial expressions. The researchers have called this the horse grimace scale (HGS) and hope it will help handlers to discern pain.

    The facial actions chosen to identify pain included visible tension around the eyes, chewing muscles and mouth, ears held stiffly backwards and strained, flared nostrils.

    These sound obvious when listed or observed at length by video, but may not be so noticeable during a quick look over the stable door or field gate.

    It is not always easy to recognise these indications of pain when you glance at a horse for just a short time.

    Causes of pain in horses

    Only when the problem has been identified can a proper pain relief protocol be put in place. If your horse:

    ➤ Has a kick wound over a long limb bone…

    … there may be an underlying hairline fracture. Any such injury or suspicious lameness should be examined by a vet, who may need to take radiographs to make a definite diagnosis.

    In such cases don’t be tempted to give the horse painkillers, such as bute, without knowing what is going on. Such treatment without a diagnosis can be dangerous, since it has the potential to make a horse feel more comfortable. If he then starts moving around, he is at increased risk of breaking the leg completely — especially if he is turned out or transported.

    ➤ Is reluctant to move…

    … be suspicious. If a pony is usually hard to catch, ask yourself if there is a problem such as laminitis. In the very early stages, laminitis pain can be helped by ice treatment to the feet as well as painkillers and other medication. If in doubt, consult your vet.

    ➤ Is reluctant to eat…

    … it is more likely that he has a health problem than is simply being fussy. A show pony I visited recently had a fractured cheek tooth and was not eating because he could not chew. While this was obvious upon examination, it could easily have been dismissed as the fact he didn’t like his new feed.

    This veterinary feature was first published in Horse & Hound magazine (5 June, 2014)