MRI T2/STIR epaxial muscle hyperintensity in some dogs with intervertebral disc extrusion corresponds to histologic patterns of muscle degeneration and inflammation.

Magnetic resonance imaging hyperintensity on T2-weighted turbo SE and STIR sequences of the paraspinal musculature in canine patients being imaged for thoracolumbar intervertebral disc extrusion is frequently observed but poorly understood in veterinary medicine. The objective of this prospective analytical study was to describe the histopathology of muscle hyperintensity in dogs with thoracolumbar intervertebral disc extrusions and to determine if a relationship exists between the presence of this hyperintensity and various patient factors. Twenty privately owned dogs who underwent surgical decompression of intervertebral disc extrusions diagnosed on MRI were enrolled (10 normal "control or nonaffected cases" without MRI paraspinal musculature hyperintensity and 10 "affected cases" with hyperintensity). Surgical biopsies of the epaxial musculature at the region of hyperintensity (affecteds) and at the site of the disc herniation (controls) were submitted for histopathology. The degree of myofiber degeneration and necrosis was scored using an ordinal scoring system: absent (0), minimal (10), mild (20), moderate (30), marked/severe (40), and massive (50). Associations between hyperintensity presence and patient age, weight, body condition, neurologic status, acuteness of onset, number of disc herniation sites, degree of spinal cord compression, and volume of herniated material were investigated. Nonaffected patients were significantly older (median age = 9.4 years) than affected patients (median age = 3.5 years), but no other significant associations were found. Acute myofiber degeneration/necrosis and intramuscular inflammation were observed in half of affected patients. Therefore, T2/STIR muscle hyperintensity in some patients with intervertebral disc extrusion may represent muscle degeneration and inflammation.

Resolution of hyperinsulinemic hypoglycemia following partial pancreatectomy in a dog with nesidioblastosis.

CASE DESCRIPTION A 6-year-old castrated male Australian Shepherd was evaluated because of a recent onset of persistent hypoglycemia. CLINICAL FINDINGS Physical examination results were generally unremarkable. No abnormalities were detected on thoracic radiographs, and abdominal ultrasonography revealed no obvious pancreatic lesion. Hematologic analysis revealed hypoglycemia with a high serum insulin-to-glucose concentration ratio. TREATMENT AND OUTCOME Insulinoma was suspected; medical treatment with prednisone was initiated, and exploratory laparotomy was performed. No pancreatic lesions or masses were observed. Partial left pancreatectomy and hepatic and local lymph node biopsies were performed. Histologic examination revealed islet cell hypertrophy and hyperplasia, with no evidence of neoplasia. Results of a PCR assay of the pancreatic tissue for Bartonella infection were negative. Clinical, biochemical, and histopathologic findings were compatible with nesidioblastosis. The clinical signs, including hypoglycemia, resolved after surgery. On follow-up examination 8 months later, the dog was apparently healthy and results of a CBC and serum biochemical analysis, including blood glucose concentration, were within respective reference ranges. CLINICAL RELEVANCE To our knowledge, this is the first report of nesidioblastosis in a dog for which clinical signs and clinicopathologic abnormalities resolved after partial pancreatectomy. Although extremely rare, nesidioblastosis should be considered a differential diagnosis in dogs with signs suggestive of insulinoma.

Long-term outcome following surgical and radiation treatment of vertebral angiomatosis in a cat.

CASE DESCRIPTION A 2-year-old 5.2-kg (11.4-lb) neutered male domestic shorthair cat was referred because of a 6-week history of progressive paraparesis. CLINICAL FINDINGS Neurologic examination revealed moderate ambulatory paraparesis with marked spinal hyperesthesia at the thoracolumbar junction. The lesion was localized to the T3-L3 spinal cord segment. Clinicopathologic testing, thoracic radiography, and abdominal ultrasonography revealed no abnormalities to explain the observed clinical signs. Advanced spinal imaging with MRI revealed an extradural right-lateralized mass originating from the L2 vertebral pedicle and causing severe spinal cord compression. TREATMENT AND OUTCOME Surgical decompression was achieved by performance of a right-sided hemilaminectomy at L2. Histologic examination of biopsy samples obtained from the mass revealed an ill-defined zone of mature vascular proliferation extending through the preexisting vertebral bone, consistent with vertebral angiomatosis. After surgical recovery, adjuvant radiation therapy was initiated with a total dose of 48 Gy administered in 16 fractions of 3 Gy each over a 3-week period. Neurologic function rapidly improved to full ambulation with only minimal monoparesis of the right pelvic limb. Results of neurologic and MRI examination performed 26 months after surgery indicated no change in neurologic status or evidence of recurrence. CLINICAL RELEVANCE To the authors' knowledge, this report was the first to describe the long-term outcome for vertebral angiomatosis in a cat. Surgical decompression and radiation therapy provided an excellent outcome in this case. Vertebral angiomatosis should be considered as a differential diagnosis for any young cat with thoracolumbar myelopathy secondary to a mass associated with the vertebral pedicle.

Blastomycotic osteomyelitis associated with severe lameness in a horse.

A 12-year-old Quarter horse gelding was presented for evaluation of severe right forelimb lameness, 2 draining tracts over the lateral aspect of the right proximal antebrachium, and weight loss. A presumptive diagnosis of blastomycotic osteomyelitis was established based on radiographs and cytology of the exudate. This diagnosis was confirmed at necropsy.