Saving Derby’s leg: A diary of a tendon injury, part 1

It was a hot, sunny August afternoon in 2009 and I brought my horse out for a lesson, as I had on many weekends. I’m experienced enough to know that when you tack up any horse you check it over, almost without thinking, for any signs of injury. I’d seen none on Derby but he felt a little odd in walk. This is not unusual for him, he can be a bit idle and he knows that if I think he might be lame, I won’t push him as much and he’ll get away with being lazy. So sometimes he likes to pretend to be a bit lame. Moving him up to trot however everything felt horribly wrong. I called to (let’s call her) Clare, who owns and runs the yard I keep him on and who also teaches me. Clare quickly saw that he had tweaked a tendon and I cursed myself for not noticing the heat in his off fore whilst I was getting him ready.

At this stage there was little we could do. When a horse first injures its tendon you need to wait before you do anything, as the damage is ongoing and needs to settle before you can make any diagnosis or prognosis. We put him on box rest (i.e. kept him in his stable and did not turn him out in the field at all) for a week. Three times a day we hosed the leg with cold water for 20 minutes each time. The vet came and saw him briefly, told us to keep doing what we were doing, and said that he would return in a week to perform an ultrasound scan. At this stage, although Derby was lame, he was not in any particular discomfort when standing still and he seemed to rather enjoy his new routine. No work, and three times a day he had a captive audience as either  myself, Clare, or whoever else we could rope in, sat with him and poured cold water down his leg. Derby loves attention and having some captive pixie perched on a stool within reach of his inquiring nose was wonderful as far as he was concerned. If he ever had to list his hobbies, hair chewing would rank quite high.

For me, it was not a good week. Derby remained completely unperturbed as I tried to work out the implications of what was going on. A horse’s foreleg is a highly specialised structure. The large joint about half way down that we refer to as the knee is the anatomical equivalent of the human wrist. Below this there is no muscle in a horse’s leg—only bone, tendon and ligament lie beneath the skin. The tendon that Derby had injured was the superficial digital flexor, i.e. the tendon nearest the skin’s surface that flexed his foot. This tendon at times carries a horse weighing around 550kg at around 30 mph (greater speeds than that if Derby were a racehorse. Fortunately, although he sometimes disputes this fact, he actually isn’t). It runs down the back of the cannon bone, a bone equivalent to the metacarpals in your hand. But it does a much tougher job as a horse is essentially running around on its finger tips and they are large animals that run at high speeds. And where you have five metacarpal bones to take relatively lesser strain, the horse has one.

Tendon injuries are often very serious. As the vet was later to explain to me, the initial damage to a tendon often causes few problems. However, the body’s response to an injury is for blood to rush to the area to help heal it. The area then swells. This is not a problem if there is room for swelling. If you bash your leg, damage within the muscle will hurt but it will recover in time. However tendons are different. The tendon fibre is encased by a tendon sheath that gives strength and allows ease of movement but when a tendon is injured the sheath prevents swelling. So the injured tissue, unable to swell, breaks down further. It is this that causes the greatest damage. You can minimise this by cold hosing the leg, reducing the heat and swelling and encouraging new tissue growth, but by the time you find the injury the damage may already have been done. Prognosis varies—some horses will go on to race again or compete at the highest levels in other equestrian sports. Some will have their activities curtailed and may only be used for light hacking. Some may never be fit to be ridden again, leaving the owner wondering whether to keep the horse indefinitely in a field or whether to have it put down.

Without an ultrasound scan (USS) you cannot really tell what the situation is but there is no point in scanning until around 7-14 days after the initial injury so that the full extent of the damage can be assessed. So for a week owners must wait, wondering if their horse will be fine or if they must make one of the most heart-rending decisions of their lives. As I said, it was not a good week.

However, when (let’s call him) Oliver, the vet, came out to see Derby to scan him, things seemed to look up. I could not take time off work but Clare was there for the vet. The farrier trotted Derby up whilst the vet watched, and he was sound again. In fact he played with the farrier, speeding up and slowing down his trot as the farrier alternated between jogging and running, because he could, because he had been shut in his stable for a week and because he likes to play. Oliver said we were to ride him in walk only on the roads for four weeks, gradually building up the distance. Then we could introduce trot work and after two weeks of that we could start schooling him again. Whilst he was in walk work we were to keep cold hosing the leg 2-3 times each day. Oliver said there was no real need to scan the leg since all the heat and swelling were gone and since Derby was sound. It was great news, although as I was to realise over the course of the next year, getting a horse over a tendon injury is something of a roller coaster.

Horses have evolved over millions of years to run away from danger. They are herbivores and are preyed upon. Their teeth are adapted to eat grass. Their eyes are on the side of their skulls so that they have almost wrap around vision. The eyes are relatively high on the skull so that the horse can see more even whilst its head is down grazing. They have long legs to run faster, meaning they also have long necks to reach down to graze. They have large torsos to hold the large digestive systems needed to break down grass. At the first sign of danger, they run. All their senses are attuned to sense danger and they can go from a standstill to 40mph quicker than a racing car. True, over 40mph and the car has a bit of an advantage but this does not detract from the fact that all their instincts tell them to gallop off at the first sign of a problem. Now vets know this and yet they will persist in telling you that a horse that has been shut in a stable for a week, that has this itching, burning, unarguable desire to gallop, buck and play, must walk quietly for 60 minutes. It was an interesting few weeks persuading Derby that it was for his own good. He felt fine, the leg no longer hurt and he wanted to run and play.

It was worse when we started trotting. If he was allowed to trot, he seemed to reason, then he could canter for goodness sake. But walk and trot he must, and on hard level surfaces. Uneven ground can twist the leg, causing it more damage. Soft ground will pull and suck at the tendon, straining it rather than strengthening it. Only a few years ago the usual cure for a tendon injury was to turn a horse away in a field for 12 months, leaving nature to heal it. More drastically people would ‘fire’ the leg, using hot metal to scar and damage the leg reasoning that as the leg healed this extra damage so it would heal the tendon. The most recent thinking, Oliver explained to me, is that tendons need careful, controlled exercise on roads. All well and good, but Oliver didn’t have to translate this into language that Derby could understand, or sit the rather over-excited bucks and leaps of protest as I evidently didn’t explain it very well.

Nonetheless Derby seemed to progress. We kept cold hosing the leg and it remained cool to the touch. There was no heat or swelling as I increased the trot work, and Derby developed a new and exciting pace that I was to refer to as ‘leapy bucky things’. It was amazing how many of these he could string together although I tried my best to remain calm and keep him calm, for the sake of his leg. We started to take him back in the school, changing from the hard surface of the road to a softer, sand surface as the leg got stronger. At first all seemed well but one day in late September, around seven weeks after Derby had first gone lame, the leg started to swell again. It was not as bad as the first time and Clare and I hoped that it was just a tweak. Nonetheless we decided that he must have a USS to see what was going on.

That scan was not good. The tendon should consist of tightly bundled fibres lying smoothly next to each other. Instead the top 25% of Derby’s  tendon looked as if someone had taken a meat tenderiser to it. As I was to realise over the coming months, what is happening on the outside of a horse’s leg, the clinical signs, do not match up with what a scan will tell you. The instrument-based laboratory signs of an injury can give a very different picture. However, Oliver was relatively sanguine. He gave us a 6-month exercise plan, said that under no circumstances were we to turn Derby out but also said that there was a 70% chance that Derby would return to full work. At 16, middle-aged for a horse, his years told against him, but he had good short cannon bones meaning the tendons would be less weak. Whilst the injury was quite severe, the prognosis at that stage was good. I knew we had a long road ahead of us, but I had no inkling of quite how tough the winter of 2009/10 was going to be for me and my horse.

To be continued…


2 thoughts on “Saving Derby’s leg: A diary of a tendon injury, part 1

  1. Hi Helen – thank you for sharing your experiences with us and its good to hear other people’s thoughts. I was wondering whether during the heat, swelling and lameness stage if Derby was weight bearing on it? My horse is week 7-8 following an injury where he has done huge amounts of damage to his superficial flexor tendon – the swelling was so much that you could see no leg definition whatsoever, however this has now halved in size and bowing. Just wondering whether you had any experience you could share on weight bearing as my horse is still not standing square and fully weight bearing all the time – he’s nearly 21 so age is not on his side.

    1. Hi Rachael. Derby was weight bearing during the initial injury. He was more or less sound in walk and about 4/10 lame in trot. You could see swelling if you looked for it but at a distance you’d have to be experienced to see anything wrong. When he injured it the last time he wasn’t truly weight bearing but I’m not sure how weight bearing during the initial injury affects outcome.
      Don’t know if that’s much help. My fear was that one day Derby would lie down and not be able to get himself back up. I’ve seen that happen with other horses and it was something I was desperate to avoid with him.

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