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distinguish between glaucoma and retrobulbar masses.High-frequency linear transducers (7.5to 10 MHz) at a depth of 4 to 5 centimetersusually allow for the best visualization ofocular structures. Ultrasound images maybe obtained either through the eyelids(transpalpebral approach) or directlythrough the cornea (transcorneal). Whilethe transpalpebral approach is more readily tolerated, as the horse does not see theultrasound probe, an increased risk of artifacts is possible with this approach.Auriculopalpebral nerve blocks are mostcommonly used to help facilitate examination. An excellent review for ultrasound examination of the equine eye is %u201cPracticalUltrasonography of the Equine Eye.%u201dJoint Ultrasonography Though ultrasound does not penetratethe surface of cartilage or bone, much useful information may be gleaned by viewing things such as joint contours, thecharacter of the synovial fluid, menisci, orassociated ligaments and tendons. Hereare a few examples of where ultrasoundmay assist in evaluating and treatingjoints.Stifle: While the three joints that makeup the equine stifle are most commonlyevaluated radiographically, X-rays give little information about the soft tissue structures of the stifle, including the medialmeniscus, a common source of stifle problems. The meniscus is evaluated in bothweight-bearing and non-weight-bearingpositions. The shape of the meniscus is concave,following the contour of the femoralcondyle. One retrospective study concluded that ultrasound was superior toarthroscopy in assessing damage to themedial meniscus. Probes used to examinethe stifle include 10 to 12 MHz linear, or 8MHz curvilinear, transducers. While cartilage is invisible on radiographs, some cartilage defects may bereadily seen on ultrasound. However, dueto the complexity of the stifle joint, accurate diagnosis of stifle problems often requires a combination of radiography,ultrasonography and arthroscopy.Tarsus: The collateral ligaments of thetarsus, as well as various tendons, including the superficial digital flexor tendon,long digital extensor tendon, gastrocnemius tendon and peroneus tertius, aremost commonly assessed with ultrasound. But due to the large, superficialtarsal pouches on the dorsal aspect of thejoint, even relatively minor wounds mayinduce septic arthritis, tenosynovitis andbursitis. In such cases, ultrasound can beused to show involvement of synovialstructures.Ultrasound-guided joint injections:Joints such as the shoulder, hip and vertebral facets are complex and not easily accessible. An ultrasound-guided techniquemay make injections of these areas easierand more accurate and help ensure an accurate assessment of diagnostic and therapeutic procedures. Ultrasound for Colic Evaluation In cases of severe colic, ultrasound maybe useful in helping veterinarians distinguish between surgical and nonsurgicalcases. For example, ultrasound may helpidentify increases in peritoneal fluid, decreased or absent small intestinal motility,or small intestinal enlargement that canaccompany conditions such as strangulating obstructions of the small bowel. Theseproblems may avoid detection by rectalpalpation.Other ultrasound findings are almostpathognomonic. For example, large colonenlargement and the inability to image theleft kidney is significantly associated withrenosplenic entrapment. Large colon torsions also may be precisely identified withultrasonography. For these reasons, mostequine referral hospitals will routinely examine the equine abdomen by ultrasoundas part of the colic examination, and itmay be done in the field.While extremely useful, ultrasounddoes not obliviate the need for a rectal examination. Research has shown this is asuperior technique for the diagnosis of intestinal dislocations and fecal impactions.A good clinical examination is still critical in evaluating cases of colic, and the results of the clinical examination andultrasound should be used together inmaking the decision for colic surgery.The applications of diagnostic ultrasonography seem almost limitless as a variety of structures may be imaged.Information obtained by ultrasonographymay be used to follow a case%u2019s progressionand develop a prognosis. If you%u2019re wondering whether ultrasound might provideyou with valuable diagnostic information,it probably can. o44 Arizona Horse Connection June, 2026