Case reveal


  • Within the dorsomedial aspect of the left carpus, at the level of the distal row of carpal bones, a large well-defined, smoothly marginated and broad based soft tissue opaque bulge (arrowheads) is identified within the extracapsular soft tissues.  
  • Mild osteophyte formation is present along the dorsal margin of the antebrachiocarpal joint.
  • 20ml of iodinated positive contrast media was injected into the described swelling. The contrast medium collected within the gravity dependent aspect of an encapsulated lesion extending distally into the proximal metacarpal region. Proximally, a well demarcated meniscus is identified. At maximal distention, no communication with the carpal joints was appreciated and the structure obtained a slightly lobular shape extending over the medial aspect of the carpometacarpal joint. A small amount of contrast material is seen within the soft tissues immediately distal to the swelling. Uptake of contrast of multiple thin, branching and anastomosing vessels are identified extending proximally and distally to the fluid collection (arrowheads).


  • Extracapsular cystic and fibrotic lesion associated with the left carpus, representing a hygroma with regional lymphatic drainage and no apparent joint communication.

A little bit more…

  • Reported to be fairly common in horses (also relatively common in cows).
  • Most often a sequela to acute blunt or low-grade repeated trauma.
  • An acquired bursa may develop from a persisting hematoma/seroma.
  • Usually not painful although original injury can be a source of pain.
  • If large, interference with carpal mobility can occur.
  • Hygromas are aseptic, although can become infected.
  • Standard radiographic view and injection of positive contrast media into the lesion are necessary for a diagnosis.
  • Ultrasonography of the affected region may be considered to assess the integrity of the surrounding soft tissues.
  • Identification of a fluid-filled structure without joint communication supports a diagnosis.


  • In early stages, drainage, steroid injections, and bandaging may be effective.
  • Surgical removal may also be considered, especially if infected.


  • Murray, Rachel C., and Sue J. Dyson. “CHAPTER• 20 The Equine Carpus.” Textbook of Veterinary Diagnostic Radiology-E-Book (2012): 374.
  • Butler, Jan. “Radiography and radiology of the carpus and proximal aspect of the metacarpus of the horse.” In Practice35.2 (2013): 85-90.
  • Dyson, Sue J., and Kees J. Dik. “Miscellaneous conditions of tendons, tendon sheaths, and ligaments.” Veterinary Clinics of North America: Equine Practice 11.2 (1995): 315-337.
  • Van Veenendaal, J. C., V. C. Speirs, and I. Harrison. “Treatment of hygromata in horses.” Australian Veterinary Journal 57.11 (1981): 513-514.