Frequency of occurrence, signalment, clinicopathologic and imaging findings, and outcomes with nontraumatic spontaneous intracranial hemorrhagic stroke in dogs

Objective To describe the frequency, clinicopathologic and imaging findings, and outcomes in dogs with spontaneous intra-parenchymal hemorrhagic stroke (sIHS). Animals Retrospective study involving 25 dogs. Clinical Presentation Medical records were reviewed for signalment; neurological, clinicopathologic, and imaging findings; anatomic localization; comorbidities; therapy; and outcome in dogs with sIHS (2010 to 2024). Lesion number, location, and volume were recorded. Outcome was defined as excellent, good, or poor. Frequency was defined out of a contemporaneous population of dogs ≥ 6 years old with an acute presentation of neurological signs. Results Affected dogs were older, small- to medium-breed dogs. Dogs often presented for neurological dysfunction reflective of a prosencephalic lesion (19 of 25 dogs) or new-onset seizures (13 of 25 dogs). A single, well-defined hemorrhage within the prosencephalon was commonly observed on MRI. Outcome was frequently excellent. Complete seizure remission was common. Larger lesion volumes were associated with poor outcomes. One dog experienced clinical signs suggestive of an additional sIHS 4 months after the initial stroke. Frequency of sIHS was 25 of 427 dogs (6%) ≥ 6 years old undergoing brain MRI. Clinical Relevance sIHS should be considered in older dogs with an acute onset of prosencephalic dysfunction and/or seizures. Following exclusion of secondary IHS, an excellent long-term outcome may be realized in dogs with sIHS, despite the presence of comorbidities. Short-term anticonvulsant therapy may be necessary. Development of poststroke epilepsy is unlikely. Dogs rarely experience another IHS.