The above horse presented with a left fore limb lameness. After a thorough lameness workup at our clinic, radiographs (X rays) were taken of the affected limb. What can you see on the X-ray and could it be causing the lameness?
The most common site of lameness in the forelimb is in the foot. A foot lameness is usually associated with an increase in the strength of pulse around the pastern and fetlock and often sensitivity when hoof testers are used to increase the pressure on the sole of the foot.
An increased digital pulse or sensitivity to solar pressure with hoof testers was not observed in this case.
Flexion of a lame limb can sometimes make the lameness worse if a joint or ligament is the source of the lameness.
Flexion did not make the lameness worse in this case.
Observing the horse move on a circle on both a soft and hard surface usually increases the level of lameness when the lame limb is on the inside of the circle. However in some circumstances (often when the lameness originates higher up the leg) the level of lameness is worse when the affected leg is on the outside of the circle.
This horse was lamer when the affected leg was on the inside of a circle. It was also worse when the horse was lunged on a hard surface. This indicated that the lameness was likely to be lower down the leg.
In the absence of heat or swelling we use local nerve blocks to segmentally block out parts of the leg. If the horse goes sound or improves 10-20 minutes after blocking out a particular area we have an indication whereabouts in the leg the lameness is coming from. We start with blocking out the foot, then the pastern, then the fetlock and so on. Once the horse ‘blocks out’ to a particular region we can use a combination of radiography and ultrasound to look for abnormalities of the skeleton and soft tissues respectively. In most instances we are then able to reach a diagnosis. However in a small number of cases MRI and more recently CT may be necessary to reach a more definitive diagnosis.
The lameness in this horse did not improve when the foot, pastern or fetlock were blocked out. It did improve though when the area between the knee and fetlock was blocked. Radiographs (X rays) were therefore taken of the cannon bone and associated structures.
Radiographs show a fracture involving the lower third of the splint bone sitting on the outside of the leg.
Splint bone fractures can heal over a 3-6 month period if a multi-layered bandage is used to support the limb and the horse is subject to box rest. However fractures of the lower third of the splint bone often fail to heal or heal with a large callus (bony lump) that can interfere with surrounding soft tissues resulting in an ongoing lameness. Better results are usually obtained when the lower part of the splint bone is surgically removed.
The owner decided to have the fractured piece of bone removed. This was successfully performed under a general anaesthetic at our clinic and the horse is currently recovering well.
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