Extramedullary haematopoiesis causing spinal cord compression in two dogs: Clinical and imaging findings, surgical treatment and histopathological features

Abstract Extramedullary haematopoiesis (EMH) causing spinal cord compression (SCC) is an uncommon condition both in animals and people. A 9‐year‐old German shepherd dog and an 11‐year‐old dobermann were referred due to progressive non‐ambulatory paraparesis and T3–L3 myelopathy neurolocalisation. Magnetic resonance imaging showed five extradural lesions causing severe dorsal SCC throughout T12–L1 in the first case, and a dorsal extradural lesion generating severe SCC at T12–T13 in the second case. Lesions were hypointense on T2‐weighted images, with signal void on T2*, and without contrast enhancement on T1‐weighted sequences. In the first case, a postmortem study was performed. Surgical treatment through dorsal laminectomy was performed in the second case. The dog recovered uneventfully. Nine months postoperatively, the dog was neurologically normal. In both cases, histopathological analysis was consistent with EMH. While uncommon, EMH should be considered in the differential diagnosis of lesions with these imaging features. Surgical treatment was associated with a favourable long‐term outcome in one case.