Ultrasound in general is the process of applying sound waves to a tissue and using the reflected energy to create an image. This non-invasive diagnostic is particularly useful in evaluating soft tissue as it is very sensitive to small differences in this medium. These waves cannot penetrate bone or air but are sensitive enough to pick up small changes in fiber pattern in tendons and ligaments.
Information gained from ultrasound can be independent of other diagnostic modalities and can also complement them, since many bony problems also involve soft tissue damage and vice-versa. Ultrasound can yield information in some circumstances where the horse’s body is too thick to radiograph, such as pelvic and thoracic imaging.
By digitizing the image, we can record still frame and dynamic images for later review. This allows us to compare to earlier imaging studies and for greater information sharing between horse owners and other veterinary practitioners. Centennial Equine has an M-Turbo machine by VetImaging with a 6-13mHz linear tendon probe and a 5-10mHz linear probe (15cm depth) for other applications.
Some of the more common applications:
- Musculoskeletal Evaluation: Primarily used for tendon and ligament evaluation in the limb, ultrasound can also identify and evaluate inflammatory conditions of joints, abnormal fluid accumulations, vascular abnormalities, some types of pelvic fracture, etc.
- Reproductive Applications: In an open mare (not pregnant), the entire reproductive tract can be evaluated and insemination timed to coincide with ovulation. Ultrasound is sensitive enough to reliably identify pregnancies as early as 12 days post-ovulation, though we recommend mares be checked at day 14. Fetal heartbeat is visual on ultrasound at day 25, and ultrasound can be utilized throughout the mare’s pregnancy to monitor placental health, etc. Ultrasound makes twin detection and reduction possible as well.
- Thoracic/Abdominal Evaluation: Ultrasound is very useful in evaluating lung tissue damage in horses with pneumonia and identifying pleural lung fluid accumulation in severe cases. It is also useful in evaluating the abdomen of foals and some abdominal organs in adult horses where body mass limits complete evaluation.