Why Is A Broken Leg So Serious For A Horse?

A broken leg can be disastrous for horses

Around about twenty years ago I had a beautiful chestnut horse that got her foot caught and, in trying to free herself, managed to break her leg in three places. I was devastated when the veterinarian said she needed to be euthanized straightaway and even to this day wonder if there was a chance she could have been saved. With the recent advances in medicine, I wondered if this would have still happened today.

Why Is A Broken Leg So Serious For A Horse? It’s not so much the broken bone that’s the problem, it’s more the horse’s inability to stay still and rest the leg combined with the risk of infection and increasing pain that can be so serious. Together these can affect the horse’s quality of life.

Over the millennia horses have evolved to be fast, nimble creatures that can reach great speeds, and while this can be a good thing it can also have a serious downside and that is the strength of their legs. While the bones in a horse’s legs are strong enough to carry its weight they’re also light enough to allow them to travel at speed. As well as the bones themselves being lightweight the lower legs also have very little in the way of soft tissue to help cushion any knocks or impacts. This means that the leg can not only break pretty easily but also that if it does break there isn’t much in the way of support to help it heal.

Why do horses break their legs so easily?

You might think that breaks and fractures only happen to racehorses or competition horses but, while they’re certainly more common amounts performance horses, they can happen to all horses, in part because of the way their legs are designed. While horses are heavy animals and their legs need to be strong enough to carry their full weight they don’t need to be as strong as you’d expect – after all the weight is distributed evenly so each leg only needs to carry a quarter of the horse’s weight. This means that their legs are much thinner and contain far fewer muscles than you might think, especially their lower legs.

Being built for speed means that their legs are lightweight and, while the upper legs contain plenty of muscle, have little in the way of soft tissue. This lack of ‘padding’ around the lower leg means that there’s little protection against knocks and bangs. In most cases, this will result in nothing more than a nasty cut or bruise it can also result in a broken bone.

Fractures can also occur when a horse’s leg hits the ground at an awkward angle, while this may lead to a sprain for us it can sometimes lead to a broken bone for horses. These sort of breaks often happen when the bone can’t take the horse’s weight so buckles then shatters.

What are the signs a horse has broken its leg?

If a horse has broken his leg they won't want to put any weight on it

It’s not always obvious when a horse has broken its leg, especially if the break is closed and there’s no sign of any loose bone. If you suspect your horse has broken his leg though it’s crucial you don’t move him any more than you need to (ie if he’s in a dangerous place you should only move him out of harm’s way) and seek your veterinarian’s advice immediately.

The most common sign a horse has broken his leg is severe lamenessOpens in a new tab., although this isn’t always the case. Other signs to look out for include:

  • The horse showing obvious signs of distress
  • The horse won’t put any weight on the leg
  • The leg is swollen, especially around the break
  • The leg feels hot, more common if there’s an infection
  • The leg doesn’t hang normally, often at an awkward angle.

Can a horse survive with a broken leg?

Rather than whether or not a horse can survive with a broken leg, the question is more one of whether or not they should. Most horses can survive but this isn’t always in the horse’s best interest, especially if they’re not able to live a normal life, have to take strong painkillers, and are prone to bouts of extreme laminitis.

The main factor in whether or not a horse can (or should) survive with a broken leg is the severity of the break. If the fracture isn’t complicated and hasn’t broken through the skin then not only can a horse survive but they may be able to do so without being hospitalized at all. If, on the other hand, the break isn’t straightforward or has broken through the skin then the likelihood of the horse surviving is low.

The most survivable fractures are ones that are below the point of the elbow, chips (where a small piece of bone has literally chipped off) and simple or incomplete fractures, around 90% of horses with these sort of fractures will not only survive but will also go on to make a full recovery and return to their former level of competition. Whereas breaks to the upper leg, that are around joints or are displaced are far less survivable.

Around 90% of horses will go on to make a full recovery from a simple or incomplete fracture

Different fracture types

With the type of fracture playing such a pivotal role in the horse’s chances of surviving a break I thought that it would be helpful to list the different types of fracture:

Type of fractureDescriptionLikelihood of survival
SimpleOne single crackGood
ComminutedSplintered bone with multiple breaksNot very likely
IncompleteOnly on one side of the boneGood
Complete (or clean)A full break right through the boneGood
DisplacedFragments of bone have moved out of placeNot very likely
Stress (or hairline)Multiple small, incomplete fracturesGood but may not make a full recovery
StarMultiple cracks emanating from a central pointDepends on how bad the cracks are
ArticularA fracture that involves a jointNot very likely
ClosedNo wound and the bone hasn’t broken the skinDepends on how the bone is broken
OpenPart of the bone has broken out through the skinNot very likely

Why are horses with broken legs euthanized?

There’s a long-held belief that horses with broken legs are euthanized because it costs too much to treat them but, while treating them can prove very expensive it’s not the reason why they are often euthanized. If that was the case then many racehorses would be treated, after all, while their racing days may be over their owners could make a vast amount of money by breeding from them. Instead, a veterinarian will take a number of different factors into account when they’re deciding what’s in the horse’s best interest.

Pain

The fracture itself may be treatable but in doing so will require the horse to not put weight on that leg for a period of time (typically six to eight weeks). This means that the horse will have to distribute the weight that that leg would have taken across the other legs, this extra weight on the good legs means that the hooves (and in particular the laminae) are subjected to a lot more pressure which can result in inflammation. This in turn can lead to laminitis which can itself be treated but will increase the pain the horse suffers from.

Open

If the bone breaks the skin then the chances are it’s also cut through the blood vessels, nerves, and even the tendons. While nerve and tendon damage can cause a lot of problems for horses it’s the blood supply that’s the most problematic. When the blood supply to the lower leg is interrupted it causes the tissue to die which prevents the leg from healing. A secondary problem with open fractures is the risk of infection.

Weight bearing

Depending on how the leg breaks it can sometimes bend before it shatters which means that even if the bone could be put back together it will still be bent and therefore won’t be loadbearing. This will ultimately have a negative impact on the horse’s quality of life as well as the amount of pain they’re in.

Treatability

It’s not that fractures can’t be repaired (even severe, articular breaks that have shattered can be fixed) it’s more that horses can’t lie still until the leg has recovered, they’re flight animals and are likely to instinctively run at the first sign of a perceived threat. On top of that horses can suffer mental and emotional stress if they’re confined for too long and not allowed to move. 

Further reading

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