Larry is lame, hopping lame. Well, not hopping lame today, but he was after eventing on Monday. Today he is limpingly lame… He’s got a splint on his nearside fore.
And looking at him, having a splint appears to be pretty painful.
What is a splint?
A splint is an inflamed area on either the inside or the outside of the canon bone. There may be a swelling and heat, and the horse will try to keep weight off the affected leg when trotting.
The front canon bone has on either side a smaller splint bone, and these smaller splint bones fuse into the canon bone as the horse matures, but in a young horse ligaments hold the splint bones to the central canon bone.
The upper two thirds of each splint bone is attached to the canon bone by the interosseous ligament (dense fibrous tissue). The lower section flares away from the canon bone and is connected to the surrounding structures by soft tissue. The lower end of the splint bone has a small pea like button, which can be felt through the horse’s skin.
As the horse matures, the ligaments ossify and all three bones become one. Usually by the age of four the splint and cannon bone will be one bone.
Splints are more likely to occur in young horses, as the ligament is still flexible.
If you feel along the sides of the canon bone outside or inside, you will find a very sore spot that indicates the inflamed area. Heat and swelling may be present and the swelling may start to feel hard as the ligament calcifies. Because of how the leg bones are angled, it is more common for splints to develop on the inside of the leg. It is also possible for a horse to develop multiple splints.
There is also a type of splint that you can’t feel called a blind splint. In a blind splint the bony reaction happens on the inside border between the splint bone and the canon bone, where it cannot be seen and it cannot be felt. With a blind splint, the swelling can impinge on the suspensory ligament.
What causes a splint?
Direct trauma is a common cause of splints. The periosteum is damaged by the trauma and new bone is laid down in the injured area. Splints caused by trauma are often seen lower down the leg than those caused by strain.
Working a horse on hard surfaces increases the concussion received by the interosseous ligament, which causes tearing. Splints caused by concussion are usually found on both front legs, most commonly on the inside of the leg a few inches below the knee.
Overworking young or unfit horses at speed or in tight circles may cause splints. The uneven loading of the limb in tight circles places excessive force on the medial splint, which can cause it to move excessively relative to the canon bone.
Horses with ‘bench kneed’ conformation can suffer from splints due to excess loading of the medial splint bone
What is the usual treatment for a splint?
The usual treatment for a splint is a short time of box rest, turnout on soft ground and reduced workload for 1 – 3 weeks, cold hosing and your vet may prescribe medication to reduce inflammation and prevent excess calcification.
DMSO with other drugs in it may be prescribed. DMSO acts as an anti-inflammatory, but it also has a property, which will enable it to also carry other drugs through the skin to the affected area.
The area where it is to be applied needs to be clean and free from dirt as the DMSO could also carry dirt through the skin of the horse.
DMSO is a solution that you paint on the splint with a brush if you have a patient, ‘good will to all men’ kind of horse.
Larry is not that kind of horse. He is more of the ‘take no prisoners’ kind and if he sees you’ve got the bottle of DMSO or smells it, he runs round his stable and turns his hind quarters on you before you can even get a head collar on him.
To be fair to him, it is lethal stuff and you have to wear gloves to apply it as it is quickly absorbed through your skin; If you do get it on your skin, you will smell like rotting asparagus; worryingly, you mustn’t touch it at all if you’re pregnant – it must be bad; you need to seek medical treatment immediately if you get it in your eyes and it can cause neurotoxicity; I’m not quite sure how come it is used so liberally in horses?
I can only guess how DMSO makes his leg feel – suffice to say, he leaps about after it has been applied!
Applying DMSO in Larry’s case, it’s easier to catch him by surprise, and wearing gloves run a small DMSO soaked ball of cotton wool quickly over the splint, or your chances of getting near him are limited. You mustn’t soak the area of the splint however, just brush it over with the solution, so a quick wipe with cotton wool will do.
Wear rubber gloves rather than vinyl as DMSO is horrible stuff and it permeates vinyl gloves and your skin very quickly. Getting the gloves off without getting it on your skin can also be a challenge, especially as there are only a handful of gloves on the side in the tack room.
DMSO needs to be applied twice a day – a source of great joy to those with the task of applying it!
The morning application is not too bad. I think Larry is still half asleep. It’s the afternoon application, when you are ready to go home, where Larry runs round his box like the clappers.
All I can say is, I hope his splint is soon better!