Degenerative myelopathy in 18 Pembroke Welsh Corgi dogs

Postmortem examination was performed on 18 Pembroke Welsh Corgi dogs (mean age 12.7 years) with clinical signs and antemortem diagnostic tests compatible with a diagnosis of degenerative myelopathy. Tissue sections from specific spinal cord and brain regions were systematically evaluated in all dogs. Axonal degeneration and loss were graded according to severity and subsequently compared across different spinal cord segments and funiculi. White matter lesions were identified in defined regions of the dorsal, lateral, and ventral funiculi. The dorsolateral portion of the lateral funiculus was the most severely affected region in all cord segments. Spinal cord segment T12 exhibited the most severe axonal loss. Spinal nerve roots, peripheral nerves, and brain sections were within normal limits, with the exception of areas of mild astrogliosis in gray matter of the caudal medulla. Dogs with more severe lesions showed significant progression of axonal degeneration and loss at T12 and at cord segments cranial and caudal to T12. Severity of axonal loss in individual dogs positively correlated with the duration of clinical signs. The distribution of axonal degeneration resembled that reported in German Shepherd Dog degenerative myelopathy but differed with respect to the transverse and longitudinal extent of the lesions within more clearly defined funicular areas. Although these lesion differences might reflect disease longevity, they could also indicate a form of degenerative myelopathy unique to the Pembroke Welsh Corgi dog.