Stroke: Cerebrovascular Accident (CVA) in Pets
It was once believed that strokes did not occur in animals. However, the increased availability of advanced diagnostics, like MRI, have shown that pets, like people, experience strokes. Similarly, strokes tend to occur when pets are middle-aged and older. They also tend to strike suddenly and without warning, though symptoms usually don’t last for more than 24 hours before stabilizing or improving. Strokes, also called cerebrovascular accidents (CVA), come in two varieties; ischemic and hemorrhagic. Ischemic stroke is obstruction of blood vessel that leads to failure of blood flow to normal brain tissue. Hemorrhagic stroke is failure of blood flow to normal tissue due to hemorrhage, and is often due to hypertension in pets.
Clinical Signs of Stroke
The signs of a stroke depend on which part of the brain is affected by the stroke. A pet may be having a stroke if you observe a very sudden onset of any of these signs:
• Disorientation • Wobbliness • Pacing or circling • Tremors • Weakness (often unilateral) • Blindness • Seizures • Head tilt • Rapid eye movement
The cerebellum seems particularly prone to stroke in dogs and cats and results in ‘cerebellar’ and/or vestibular signs. These cases are often mistaken as idiopathic or geriatric vestibular syndrome. This is why a complete diagnostic work-up, including an MRI should be considered for all older dogs that have an acute onset of vestibular signs.
The only way to determine if your pet had a stroke is with an MRI. An MRI provides detailed images of the brain that x-ray or CT-scan cannot. A spinal tap may also be needed to rule out any type of inflammatory brain disease. Glial cell brain tumors, inflammatory conditions and stroke can sometimes be difficult to differentiate from one another, even with detailed MRI. Once stroke has been determined, additional tests are often recommended to check for diseases that can potentially cause a stroke. Additional tests might include chest and abdominal x-rays, abdominal ultrasound, blood tests (coagulation profile, endocrine testing) echocardiogram.
Causes and Prevention of Stroke
Unlike people, arterial disease like atherosclerosis is uncommon in pets (possible exception being with chronic hypothyroidism). Common predisposing causes include high blood pressure, heart disease (bacterial endocarditis in particular), metabolic disease, Cushing’s disease, clotting abnormalities in the blood, adrenal tumors (pheochromocytoma), cancer, protein-losing kidney disease (common). Early detection and treatment of these diseases may help prevent a stroke. Pets should have routine examinations and general health screenings. Regular blood work, ECG, blood pressure checks and thyroid testing can help identify a number of health issues. In older cats, blood pressure monitoring is especially important due to increased incidence of high blood pressure secondary to conditions like chronic kidney disease and hyperthyroidism.
What to do when stroke is suspected
1. Check blood pressure (and in cats, check retinas for hemorrhage or detachment)
2. Check blood pressure
3. Check blood pressure (not a typo)
4. Routine CBC, serum chemistry with T4, urinalysis and UPC if indicated.
5. Send for Neurology consultation and MRI to confirm stroke and rule out brain tumor
6. Consider Chest rads, echo, and abdominal ultrasound if stroke confirmed or suspected on MRI
In general, the prognosis for dogs and cats is better than for people who have experienced a stroke. This is mainly because dogs and cats can still function despite serious brain injury—no requirement for higher math, fine motor skills, or witty conversation. Still, pets that have had a stroke need time to recover, good nursing care and physical therapy. Additional therapies should be aimed at managing underlying diseases that have been identified. Of course how well a pet responds to treatment depends on the size and location of the stroke—like people. Most dogs and cats that are going to recover show significant improvement within 7 to 10 days.
Recognition of Stroke is important! Signs of stroke can easily be mistaken for sign of brain tumors. Stroke carries a much better prognosis than brain tumors! Don’t mistakenly make a clinical diagnosis of ‘brain tumor’ and miss stroke, which will resolve on its own and be unlikely to recur if the underlying condition is identified and managed.
Some of the content of this article borrowed with permission from Animal Neurology Insights, a publication by The Animal Neurology and MRI Center, Commerce, MI, Dr. Michael Wolf