Merck Manual

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Imaging Techniques for Evaluation of Lameness

Imaging Techniques for Evaluation of Lameness

  • X-rays: X-rays allow evaluation of bony tissues and reveal longterm changes. Contrast x-rays (x-rays taken after a dye has been administered to the horse intravenously) provide information about joint cartilage and other structures and are of particular value in determining whether cysts below the cartilage interfere with the joint.

  • Ultrasonography: Ultrasonographic examination can be used to evaluate most soft tissues. It is most useful in the evaluation of tendons and ligaments but can also be used to evaluate muscle and cartilage. Used together, x-rays and ultrasonography provide a complete picture of bony tissues and the soft tissues that connect and support them.

  • Magnetic resonance imaging (MRI): An MRI can provide more details of bone, soft tissues, and body fluids. Although one type of MRI is only performed on anesthetized horses, another type can evaluate the lower limb in sedated, standing horses.

  • Computed tomography (CT scan): CT scans require anesthesia but provide the clearest possible image of the limbs, joints, and neck.

  • Thermography: This noninvasive technique creates a picture of the surface temperature of an object. It measures emitted heat and is useful for detecting inflammation that may contribute to lameness. Disease and injury nearly always affect blood circulation, which in turn affects the temperature of an injured area. Due to the increased blood flow to an affected area, thermography can identify “hot spots” of local inflammation. If a disease reduces blood supply to a particular area, that area of decreased heat is usually surrounded by a warmer rim, which thermography can also identify.

  • Scintigraphy: During scintigraphy, a small amount of a radioactive substance is injected intravenously. Because inflammation causes a local increase in blood flow, the radioactive substance will accumulate in the inflamed area. It also accumulates more in injured bone. A special camera that is sensitive to the injected radioactive substance is then used to locate the affected area.