Strokes in cats happen when blood flow to the brain is suddenly blocked or when a blood vessel in the brain ruptures and bleeds. While far less common than in humans, strokes do occur in cats, and they’re often linked to an underlying disease the owner may not yet know about. Understanding the causes can help you recognize risk factors early and get your cat the care it needs.
Two Types of Feline Stroke
Cat strokes fall into the same two categories as human strokes: ischemic and hemorrhagic. Ischemic strokes, which are more common, happen when a clot or other material blocks an artery supplying the brain. The blockage cuts off oxygen to brain tissue, and if it lasts long enough, that tissue dies. The clot can form locally in a brain artery or travel from somewhere else in the body, such as the heart.
Hemorrhagic strokes occur when a blood vessel in the brain ruptures. Blood leaks directly into the brain tissue or the surrounding space, forming a clot that physically compresses and damages the brain. Because this type creates rising pressure inside the skull, neurological signs can worsen rapidly over a short period. Hemorrhagic strokes in cats have been linked to ruptured congenital vascular abnormalities, bleeding into brain tumors, and inflammatory disease of the blood vessels.
Heart Disease Is the Leading Cause
Hypertrophic cardiomyopathy (HCM), the most common heart disease in cats, is a major driver of stroke. HCM thickens the walls of the heart, which disrupts normal blood flow inside the chambers. Blood can pool and form clots, which then break free and travel through the bloodstream. When a clot lodges in a brain artery, the result is an ischemic stroke. Between 12% and 21% of cats with HCM develop arterial blood clots, a complication known as feline arterial thromboembolism. While these clots most famously lodge in the hind legs, they can also reach the brain.
High Blood Pressure and Its Hidden Triggers
Hypertension is one of the most important stroke risk factors in cats. A normal feline systolic blood pressure sits below 150 mmHg. Readings above 180 mmHg place a cat in the high-risk category, and neurological problems, including disorientation, seizures, balance loss, and limb weakness, appear in 15% to 40% of hypertensive cats. These signs are most likely when blood pressure rises quickly.
What makes feline hypertension especially dangerous is that it’s almost always secondary to another disease. The two most common culprits are chronic kidney disease and hyperthyroidism, both of which are widespread in older cats.
Chronic Kidney Disease
As the kidneys lose function, waste products build up in the bloodstream and the body struggles to regulate fluid balance and blood pressure. Cats with chronic kidney disease are at increased risk for hypertension, which in turn can cause sudden neurological changes, vision loss, and stroke. Because kidney disease develops gradually, blood pressure can climb for months before any obvious signs appear.
Hyperthyroidism
An overactive thyroid gland doesn’t just speed up metabolism. It also makes the blood more prone to clotting. Hyperthyroid cats show elevated levels of several clotting factors and proteins that inhibit clot breakdown, creating what researchers describe as a hypercoagulable state. On top of that, roughly 60% of hyperthyroid cats in one study also had high blood pressure, which damages blood vessel walls and further raises the risk of clot formation. This combination of thicker, stickier blood and damaged vessels is a recipe for ischemic stroke.
Brain Tumors and Vascular Malformations
Tumors inside the brain, whether they originate there or spread from elsewhere, can trigger hemorrhagic strokes. As a tumor grows, it can erode into surrounding blood vessels or develop fragile, leaky blood vessels of its own. When those vessels rupture, blood spills into the brain tissue. Congenital vascular abnormalities, essentially malformed blood vessels a cat is born with, can also rupture without warning and cause hemorrhagic stroke at any age.
Parasitic Causes
One unusual cause worth knowing about is Cuterebra, a type of botfly larva. Outdoor cats can pick up these parasites, and in rare cases, the larvae migrate into the brain through openings at the base of the skull, such as the thin bone behind the nasal passages. Once inside the brain, the migrating larva is thought to release substances that trigger spasm in cerebral arteries, cutting off blood flow and producing ischemic damage. This condition, sometimes called feline ischemic encephalopathy, may be preceded by upper respiratory signs as the larva travels through the nasal area before reaching the brain.
Inflammatory Blood Vessel Disease
Inflammation of the arteries and veins inside the brain, known broadly as vasculitis, can damage vessel walls enough to cause either blockage or rupture. The inflammation may stem from infections, immune-mediated conditions, or other systemic diseases. This is a less common pathway to stroke in cats, but it’s one reason veterinarians often look for signs of infection or immune dysfunction when evaluating a cat that has had a stroke.
Why Strokes Often Go Undiagnosed
Strokes are infrequently reported in cats. One veterinary referral center identified just nine feline stroke cases over an 11-year period, compared with 40 cases in dogs at a similar facility over roughly four years. Part of this is genuinely lower incidence, but part of it is likely underdiagnosis. MRI is the most sensitive tool for detecting ischemic strokes and subtle brain changes, but it requires anesthesia and isn’t available at every veterinary clinic. CT scans can reveal larger strokes and hemorrhages, but they miss smaller ischemic events. Many mild strokes in cats probably go unrecognized or are attributed to other causes.
A presumptive diagnosis typically relies on the combination of sudden neurological signs, ruling out other causes, and imaging findings when available. Identifying the underlying disease, whether it’s heart disease, kidney failure, hyperthyroidism, or something else, is a critical part of the workup because treating the root cause is what reduces the chance of another stroke.
What Recovery Looks Like
Most cats that survive a stroke tend to recover within a few weeks, though the degree of recovery depends heavily on which part of the brain was affected and how much tissue was damaged. A stroke involving a critical area may leave permanent deficits, while cats with smaller strokes often regain most or all of their normal function. You might notice your cat tilting its head, circling, or seeming disoriented in the days following a stroke, with these signs gradually improving.
The long-term outlook hinges on the underlying cause. A cat whose stroke was triggered by uncontrolled high blood pressure has a better prognosis once that blood pressure is managed than a cat with an aggressive brain tumor. Recurrence is always a concern, which is why identifying and treating the root condition matters more than treating the stroke itself.