Contents under pressure: vascular proliferation and gliosis in the brains of Cavalier King Charles Spaniels with syringomyelia.

Vascular and astroglial changes in the central nervous system of Cavalier King Charles Spaniels (CKCS) affected by Chiari-like malformation (CM) and secondary syringomyelia (SM) and ventriculomegaly (VM) are poorly characterised. CM is a developmental malformation of brachycephalic breeds and is a significant welfare concern, especially for CKCS in which this disorder is considered ubiquitous with varying degrees of severity. A frequent sequela of CM is SM and VM, causing a range of neurological clinical signs. Nineteen deceased CKCS diagnosed with CM were donated for the purposes of research, from which two groups were selected for examination: those with SM and VM (n = 13) and those without SM and VM (n = 6). Periventricular tissue samples were collected, processed routinely for histology, and stained with H&E, Martius Scarlet Blue (MSB), and glial fibrillary acidic protein (GFAP). Dogs with SM and VM demonstrated increased angiogenesis (23.62 ± 6.79 vs. 11.67 ± 4.93 mean blood vessels per 100x magnification field), and increased vessel wall thickness (71.61% ± 5.14 vs. 58.73% ± 6.47 of total vessel diameter) and greater astrocyte activation, indicated by increased GFAP immunoreactivity, what could be associated with chronic pressure trauma and hypoxic insult resulting from altered vascular compliance. These findings provide insight into the pathological mechanisms associated with CM and its sequelae and may inform future investigations into diagnostic biomarkers and therapeutic targets.