The lameness exam can vary in length and complexity depending on each individual presentation. Lameness can present as a single limb or multi-limb lameness. Lameness issues can also have a more subtle presentation with a complaint of poor performance or change of attitude, can be seen undersaddle but not on the lunge line or vice versa, or even intermittently present from day to day. To begin to sort out each case the exam typically includes observing the horse at the walk, lunging on hard and soft ground and evaluation of the horse undersaddle or being driven. Limb palpation, back and neck flexibility and limb flexions are also part of the exam. The musculoskeletal system is checked for any asymmetry or unusual stance position.
Once the gait deficiency has been identified and described by the limb (or limbs) affected, whether it is a weight bearing or swing phase lameness, what type of surface and at which gait the lameness is most prominent then nerve and joint blocks can be done. The horse is re-evaluated after each block to localize or eliminate a specific area as a possible source of the lameness. Once the source of the pain is localized, or in some cases if blocks are not possible or recommended, imaging is the next step in the lameness work up.
Limb, neck and back radiograph and ultrasound images can be done in the field to determine the soft tissue or musculoskeletal abnormality that may be the cause of the discomfort. Frequently bone and soft tissue changes are seen together and occasionally both imaging modalities are needed to fully understand the extent of changes responsible for the gait deficients. In some cases radiographs and ultrasound do not adequately image an area and a MRI exam can be done to provide further information. Nuclear scintigraphy is another modality that can provide information to determine the source of the pain, but as with all imaging the findings must be interpreted carefully.
Once the diagnosis is determined various treatment options are discussed and decisions can be made based on each individual case.