The Importance of Palpation and Surface Anatomy

Horses are a large mammal with a complicated skeletal system. The horse’s back, hindquarters, and fetlocks are prone to injury and ill health due to their specialized anatomy. It is important for veterinarians to recognize these skeletal landmarks in order to palpate the horses and detect pain and lameness.

Although radiography, ultrasonography and computed tomography are valuable diagnostic tools, they do not replace detailed visual inspection and palpation of the weightbearing and nonweightbearing limbs. A thorough examination should include a comparison of the limbs with the contralateral limb. In addition, a comparison of the feet should be performed by applying compression to the soles with hoof testers.

The presence of heat, swelling and joint effusion should also be assessed. The horse should be palpated for asymmetry, muscle loss, abnormal stance and injury. The limbs should be examined for extension and flexion range of motion as well as for the presence of a medial femorotibial (kneecap) joint depression. This depression is located caudal to the medial collateral ligament and proximal to the greater trochanter. It is important to note that the equine fetlock does not contain the gastrocnemius or popliteal sesamoid bones found in dogs and cats. Instead, a bony structure known as the femoral trochlea contains two large ridges separated by a deep groove. The medial trochlea is larger than the lateral and extends farther forward in the horse.

Observation of the horse walking in a straight line and lunging on a firm surface is important as it allows the examiner to listen for the sound of each foot hitting the ground. However, it is important to realize that impact sounds are affected by a variety of factors including the shoeing system and the terrain. Therefore, they may not be as useful as they might seem to be for detecting an abnormal gait.

In a recent study, body painting was used as a non-invasive technique to help students learn surface anatomy by observing, identifying, palpating and drawing [1, 2, 3]. This approach is highly captivating and engaging for students and has been successfully used in human anatomical education involving both first year and senior undergraduate students. However, to date no research has been published on the use of body painting in veterinary student education.

The committee viewed 61 videos of inspections done by DQPs at TWH shows and found that these DQPs did not adequately observe the movement of the horse’s back during its gait. This may result in missed findings of abnormal gait movement or an inadequate assessment of the horse’s response to palpation. Additionally, the DQPs did not assess whether the horse was on medications that might hinder its ability to respond to palpation. Blood testing for NSAIDs, opioids and local anesthetics would allow the DQPs to determine whether drugs are being administered that could interfere with the horse’s ability to be detected as sore by palpation. This information could then be compared with the horse’s response to palpation during the HPA screening inspection in order to improve future inspections.