Strokes are an increasingly common cause of seizures and other intracranial signs in dogs (and cats). Why is the diagnosis becoming more common? My theory is that we are simply performing more MRIs, and therefore making the diagnosis more readily, but it is possible that increasing comorbidities or breed related changes may contribute to the increase in diagnosis.
What is a Stroke?
Stroke, or cerebrovascular disease (CVD) occurs when normal brain fuction is disrupted due to hemorrhage or infarction. CVD is typically due to occlusion of an/multiple intracranial vessels however hemorrhagic strokes can occur in rare cases. Around 50% of dogs will have an underlying predisposing facture such as hyperadrenocorticism, hypothyroidism, protein loosing nephropathy, heartworm disease, heart disease (less common as a cause!) or other "hypercoagulable" diseases. The other 50% do not have any identified predisposing factors and are therefore considered to have had an idiopathic vascular event.
Clinical presentation
Acute onset, with progression not typically noted after 24 hours (but it can in rare cases)
Common in older dogs, less common/rare in younger dogs
Gait changes (hypermetria, ataxia) and seizures were the two most common presenting complaints leading to a diagnosis of CVD
Diagnosis
The best diagnostic tool for CVD is MRI. Indication of vascular occlusion can be seen immediately but tell-tale signs may resolve if imaging is performed too long after the onset of the clinical signs.
Treatment
Supportive treatment is often the only treatment needed. Supportive treatment may include anticonvulsant drugs, intensive nursing care if non ambulatory, or rehabilitation if gait abnormalities are identified. A neurology consult may help guide treatment for you and the client.
Outcome
The majority of dogs will improve following CVD but time to improvement and degree of improvement is variable, and based on severity of neurologic impairment, and MRI findings. Recurrence can occur, but is less common. We previously though it was rare, but in one study in Japan (see below) 11 of 50 cases available for follow-up had clinical signs of recurrence of disease after a diagnosis of CVD. Recurrence does not mean seizures - remember they can develop a seizure disorder secondary to a CVD but that does not suggest progression!
Other Cool Facts
The Japanese study referenced below noted August and December as months with significantly higher stroke diagnoses, compared to all other months, and October as the lowest month. Interesting!
Thanks for reading! Have a great week and keep those consults rolling! I will be speaking at the Michigan Vet Med meeting in Lansing and at the Chicago Vet conference the week of May 9th so no live consults will be available that week. However, I will be reachable by email or telephone if you need me. I look forward to working with you when I return!
Reference: Ozawa T, Miura N, Hasegawa H, et al. Characteristics of and outcome of suspected cerebrovascular disease in dogs: 66 cases. JSAP (2022)' 63, 45-51.