Clinical Activities and Procedures

Photo: Metacarpal (Fore) & Metatarsal (Hind) Ultrasound

Metacarpal (Fore) & Metatarsal (Hind) Ultrasound Evaluation of the metacarpus or metatarsus is indicated in horses whose lameness has been localized to either region through the use of diagnostic nerve blocks or in horses with regional swelling. Structures evaluated include the superficial digital flexor tendon, deep digital flexor tendon, inferior check ligament and suspensory ligament. Normal tendons and ligaments show an evenly white or echogenic appearance on transverse (cross-section) views and a linear fiber pattern on longitudinal views. Injuries typically cause enlargement (as measured by cross-sectional area) and create hypoechoic (dark) areas within the injured structure as shown in the center image. Ultrasound was used to determine that an inferior check ligament (ICL) injury was the cause of swelling and lameness in this Dutch Warmblood show jumper. The top right image shows severe enlargement of the ICL with a hypoechoic (dark) area and irregular fiber pattern. This can be compared to the normal appearance of the ICL (arrows) shown at bottom right.

The Large Animal Ultrasound Service offers a complete range of ultrasound imaging procedures. Many studies are performed to examine tendons, ligaments and joints as part of the comprehensive evaluation of horses with lameness or performance problems. Other horses present for thoracic or abdominal ultrasound to evaluate for problems associated with the lungs, heart, abdominal organs or gastrointestinal tract.

Musculoskeletal Examinations include:

  • Metacarpal and metatarsal
  • Pastern
  • Joints
  • Neck/Back
  • Abdominal
  • Cardiac and Thoracic
  • Pelvic
  • Head
  • Ultrasound guided procedures

Metacarpal and metatarsal ultrasound is often performed to diagnose superficial digital flexor tendon or suspensory ligament injuries. Injuries to the deep digital flexor tendon and inferior check ligament do occur but are less commonly identified.

Pastern ultrasound is indicated in horses with lameness localized to the pastern or foot, pastern swelling or digital sheath effusion. Ultrasound can diagnose injuries to the deep digital flexor tendon, distal sesamoidean ligaments, branches of the superficial digital flexor tendon and other small ligaments of the pastern region.

Joint ultrasound examinations of the coffin joint, fetlock, carpus, elbow, shoulder, stifle and tarsus (hock) can be used to diagnose injuries of the collateral ligaments or other regional tendons or ligaments. In horses with wounds, ultrasound can help to determine if the joint or other synovial structure (such as a tendon sheath) has become infected. This information helps to determine the need for additional diagnostic procedures or surgical intervention. 

Neck and back ultrasound, such as cervical & lumbosacral ultrasonography can be used in conjunction with radiography to diagnose various conditions such as arthritis of facet joints (cervical & lumbar), sacroiliac ligament injuries and lumbosacral/sacral abnormalities. Transrectal examination of the lumbosacral region is used to detect abnormalities of the lumbar and lumbosacral disc spaces, sacroiliac joint, sacrum and sacral nerve roots.

Abdominal ultrasound is often performed by our service in horses with chronic or recurrent colic, fevers, weight loss, diarrhea, urinary problems or suspect masses. These exams can be very rewarding, often leading to a diagnosis of internal abscessation, liver disease, renal disease, colitis, inflammatory bowel disease, peritonitis and even neoplasia (cancer). In horses with acute colic, abdominal ultrasound is routinely performed by our Equine Emergency Service to help determine the need for surgical intervention.  

Cardiac and thoracic ultrasound is also performed by our service, although many horses with pulmonary or pleural disease are imaged by our Equine Medicine Service. Thoracic ultrasound is primarily indicated in horses with fevers, nasal discharge, abnormal lung sounds or coughing. Although not cardiologists, our ultrasound faculty do have specialized training in large animal cardiology, and also work closely with the hospital’s board-certified cardiologists to properly evaluate any cardiac concerns in horses. Echocardiography is indicated in horses with murmurs, reduced exercise tolerance and other signs of cardiac disease.

Pelvic ultrasound is used for the diagnosis and localization of pelvic fractures is an area of particular interest to the Large Animal Ultrasound Service. Over the past 10 years, the Service has diagnosed nearly 100 affected horses. Depending on the fracture location and severity, many horses can have a successful outcome after a period of confinement. Although radiography or nuclear scintigraphy (bone scan) can detect pelvic fractures, ultrasound is quick, less expensive and does not require general anesthesia.

Head ultrasound is usually performed in horses with regional swelling to determine its cause. Potential abnormalities include abscessation due to tongue foreign bodies, temporomandibular joint infection, salivary abnormalities (abscessation or sialoliths), osteomyelitis (bone infection) or fracture of the mandible or skull.

Ultrasound guided procedures are performed on a daily basis by the Service. Ultrasound guidance ensures that an intralesional product (such as stem cells, platelet rich plasma, etc.) is placed precisely within the injured portion of a tendon or ligament. It also ensures accurate placement of therapeutic agents into joints, tendon sheaths or bursae, including the cervical facets, sacroiliac joint, hip joint, shoulder joint and bicipital bursa. Ultrasound guidance is also routinely used to obtain samples from abdominal organs (liver, spleen, kidneys), masses or abscesses in horses and other large animal species.