Giuseppe Vitello 1, Beatrice Enrica Carletti 2, Sergio A Gomes 3, Luca Motta 4, Alessia Colverde 5, Andrea Holmes 1, Massimo Mariscoli 1
Background
Steroid-responsive meningitis-arteritis (SRMA) is an immune-mediated disease in dogs characterized by inflammation of the leptomeninges and associated arteries. Although common in young dogs, SRMA can rarely progress to haemorrhagic myelopathy due to systemic vasculitis. This complication remains poorly characterized. The study aims to describe the clinical presentation, MRI findings, treatment responses, and outcomes of dogs diagnosed with haemorrhagic myelopathy secondary to SRMA.
Methods
This was a retrospective, multicentre study of nine dogs diagnosed between 2017 and 2024 at five UK veterinary referral centres. Inclusion criteria were based on clinical signs consistent with SRMA, supportive CSF analysis, elevated inflammatory markers, MRI or surgical confirmation of spinal haemorrhage, and exclusion of other causes. Data were collected on clinical presentation, diagnostic findings, treatment, and outcomes. MRI was the principal imaging modality used to classify haemorrhage type and location.
Results
The study population included dogs aged 9 to 78 months, with a predominance of young females. Common clinical signs were cervical hyperesthesia, pyrexia, and lethargy. Neurological presentations varied from ambulatory tetraparesis to paraplegia without nociception. MRI revealed haemorrhagic lesions primarily in the T3–L3 region, most frequently intradural–extramedullary in location. CSF analysis typically showed neutrophilic pleocytosis and elevated protein. Immunosuppressive treatment, mainly with prednisolone (with or without cytarabine or other agents), was effective in five cases. One case with compressive extradural haemorrhage was treated surgically with good recovery. Three dogs with severe neurological signs were euthanized due to poor prognosis. Post-mortem examination in two cases confirmed widespread CNS haemorrhages and vasculitis.
Limitations
Limitations include the small sample size, retrospective design, lack of uniform treatment protocols, incomplete diagnostic testing (e.g., tertiary haemostasis), and absence of IgA measurement, which is a known SRMA biomarker. CSF analysis was not feasible in all cases due to technical or safety concerns.
Conclusions
Haemorrhagic myelopathy is a rare but serious complication of SRMA, more commonly affecting the thoracolumbar spinal cord. Timely diagnosis using MRI and a comprehensive clinical workup is essential. Immunosuppressive therapy is effective in many cases, and surgical intervention may benefit selected patients. This study underscores the need to include SRMA in the differential diagnosis of dogs presenting with spinal haemorrhage and neurological deficits, particularly in young dogs.
Crossbreed (case 1), male neutered, 9 M. transverse T2W image (A), transverse T1W image (B), and transverse T2* GRE image (C). Magnetic resonance shows intradural–extramedullary lesion compressing the spinal cord to the right at the level of T12-T13 (orange arrows). This corresponds to the site of the green line in the sagittal post-gadolinium-based contrast agent (GAD)-weighted image (E). Transverse T1W image of gadolinium-based contrast agent (GAD) (D), sagittal T1W image of gadolinium-based contrast agent (GAD) (E). Magnetic resonance shows a tubular well-defined lesion hypointense at level T12-L1 (green arrows) that shows a faint dependent contrast enhancement, indicating it is likely fluid-filled and possibly subject to active haemorrhage. It appears to be surrounded by the dura matter, indicating a mostly intra-dural component. The meninges show multifocal ill-defined enhancement. The peridural fat at this level is also partially attenuated and very heterogenous, indicating there is extra-dural involvement.
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