A warmblood mare was kept running free in a large pasture area. She was seen by the owner several days ago and she was slightly lame at that time on the left hind limb. The lameness remained unchanged over the next days and she was eventually presented for examination and possible treatment.On palpation, a small, warm soft tissue swelling was noted in the midportion of the metatarsal region dorsomedially. The skin showed signs of an old injury, and there was evidence of a chronic draining tract that was closed. Four radiographic views were made of the affected limb. An oblique and lateral views are show. What is the diagnosis and treatment suggested.Radiographic diagnosis - osteomyelitis with sequestration The sequestrum is seen as a dense, well marginated fragment of cortical bone surrounded by a radiolucent zone. The new bone forming around the lucent zone is called the involucrum and appears as a margin of new bone tissue surrounding the infected area. The involucrum in this patient is protruding only slightly. The opening through the involucrum is referred to as the cloaca and provides a location for a draining tract. Lesions of this type continue to present with a chronic draining tract during long-term healing and therefore are best treated with surgical currettage that achieves a more rapid and complete healing.Comparison of the pre and postoperative radiographs clearly shows the success of the surgery (arrow). Joe P. MorganProfessor EmeritusDepartment of Surgical and Radiological SciencesSchool of Veterinary MedicineUniversity of CaliforniaDavis, CA 95616jpmorgan@ucdavis.edu
