Evaluation

In general, horses are evaluated for orthopedic abnormalities and lameness while standing quietly and when moving. The moving examination may include examination at the walk or trot or under saddle. Horses may be evaluated on the straight line, on a lunge circle or under saddle, on an asphalt surface, or on a sand riding surface. Hoof-tester examination and a variety of flexion tests may be performed. This initial examination determines how many limbs the horse is lame on-- it is not uncommon for a horse to be lame in all four of its legs at the same time! In addition, some horses are lame at more than one site in a single leg. All these lamenesses must be considered in order for the veterinarian to give you the best recommendations. Sometimes if multiple limb lamenesses are identified at this time, or if the horse is intractable, a bone scan is recommended, to try and localize the lameness as much as possible with a minimal number of nerve or joint blocks.

Lameness Isolation

The next step after an initial examination is to isolate the lameness to a particular area. This is accomplished by 'nerve blocks' (injecting a local anesthetic solution around the nerve supply to desensitize a specific region of the limb), or 'joint blocks' (injecting a local anesthetic solution directly into a joint). These blocks generally take 5-20 minutes after injection to achieve maximum effect, and the patient will be re-evaluated during this time. Depending on the response to the block, further nerve or joint blocks may be performed. Occasionally, it is necessary for a nerve block to wear off before a more specific joint block can be performed. This may take several hours.

Treatment Options

When the lameness can be isolated to a specific region of the limb or a joint, imaging of that region is recommended to identify abnormalities in structures that may be causing the lameness. Typically radiographs or an ultrasound examination may be the first step and in some cases, MRI examination, or bone scan may be recommended after this. The imaging modality that is recommended is chosen to maximize the chances of identifying the abnormality, and a number of factors must be taken into account during this decision making process.

Surgical exploration of a joint by arthroscopy, with the patient under general anesthesia is sometimes recommended to both diagnose and treat a specific abnormality. Visualization of the inside of the joint using the arthroscope (a small camera) can also be used to give a prognosis of how well the horse is expected to recover from the lameness.