Page 64 - May 2018 Speedhorse

is worked in circles, strain is increased on the lateral side of the inside leg and the medial side of the outside leg. In some horses, lameness is not exacerbated by circling, or not present on baseline evaluation, and the horse will need to be ridden under saddle or evaluated while it is performing in its respective discipline.
Once a baseline lameness evaluation is complete, and the limb(s) of interest has been identified, flexions of upper and lower limbs are typically performed. Flexion tests are used to exacerbate baseline lameness or to exacerbate a painful issue that was not visible on baseline evaluation. This is a subjective evaluation and horses of different ages can respond differently. Veterinarians use these tests to add addi-
tional information to their baseline lameness evaluation. Following the baseline lameness evaluation and flexions tests, nerve and/or
joint blocks are often used to help localize the lameness to the part of the limb that is painful. Nerve and joint blocks involve injecting local anesthetic solution around nerves or into a joint to numb the pain if it is coming from that area. The location of the pain is identified based on the location of the nerve or joint block that improves the lameness. It is always preferred
to have an accurate diagnosis so that treatment recommendations are focused on the specific cause of lameness in each individual horse.
For example, if a horse does not block to a foot nerve block, but blocks to a fetlock nerve or joint block, radiographs of the horse’s fetlock would be performed to determine if there was any bone abnormality visible on the radio- graphs. If radiographs were normal, an ultra- sound evaluation of the fetlock region could be done to look at soft tissue structures around the fetlock. Furthermore, if no cause of the lame- ness was found with radiograph and ultrasound evaluation of the fetlock, magnetic resonance imaging may be recommended to perform a more in-depth evaluation of the bone and soft tissue structures in the horse’s fetlock.
Case example
A 10-year-old Quarter Horse gelding used for barrel racing presented for a hindlimb lameness that was recently identified. The horse had a consistent right hind lameness in a straight line and circling both directions, but the cause of the lameness was unknown. There was no obvious
swelling of the limb. The horse was more posi- tive to upper limb flexions tests than he was to lower limb flexion tests. A decision was made to block the horse’s two lower hock joints because hock pain can be a common cause of lameness in western performance horses. After the joint block was performed, the horse was significantly less lame in the right hind limb. The joint block had taken away at least 70% of the pain in the limb and, therefore, the area that was causing the lameness was identified. However, we still did not know the cause of the pain. Radiographs were then taken of the right hock, but there was no injury visible to any bones of the hock. The next diagnostic step to more completely evaluate the bones and soft tissue structures of the hock was magnetic resonance imaging (MRI). This horse then had an MRI evaluation done on
the right hock and a non-displaced, complete fracture of the central tarsal bone was identi- fied. Now that we had a definitive diagnosis of the cause of the horse’s pain, treatment could be instituted to give this horse the best chance to return to performance. The horse was then taken to surgery to put two lag screws through the tarsal bone fracture. The horse was rested for 3 months and then was able to return to a conditioning program to prepare the horse to return to competition.
Once a baseline lameness evaluation is complete and the limb(s) of interest have been identified, flexions of upper and lower limbs can be performed. Flexion tests are used to exacerbate baseline lameness or to exacerbate a painful issue that was not visible on baseline evaluation.
Magnetic resonance imaging (MRI) is a diagnostic tool used to more completely evaluate bone and soft tissue structures.
examination of the horse for lameness begins with a thorough and accurate history. The history can be as important as the clinical signs in leading one to a diagnosis, and this is especially true for difficult or obscure lameness problems.
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