Times change, huh? When I trained — cough — years ago, I was taught that animals don’t have strokes. After I graduated, it didn’t take me long to find that this flew in the face of what I saw regularly in practice.
Now science has caught up with the obvious, and yes, it is now recognized that cats and dogs do suffer from strokes — but the signs are subtly different from those of strokes in people.
Sophisticated imaging techniques, such as MRI or CT scans, show us that there are 2 types of strokes:
- The first, ischemic stroke, is the result of a sudden loss of blood supply to part of the brain. An example of this is a blood clot causing a blockage.
- The second, a hemorrhagic stroke, is bleeding within the brain that interferes with oxygen exchange to vital tissues.
5 Symptoms of a Stroke
In people, the most common signs of a stroke are partial paralysis down one side of the body and a drooping face.
This is not the case for pets. They are far more likely to suffer:
- A loss of balance
- A head tilt
- Circling when they try to walk
- Collapsing to one side
- Nystagmus, where the eyes track from side to side as if watching an invisible tennis match
Be aware that these symptoms can be caused by reasons other than a stroke, so a dog with a head tilt may have a sore ear rather than be suffering from a stroke.
Several medical conditions, such as heart disease, kidney disease, high blood pressure and overactive thyroid glands, can increase the likelihood of a blood clot being thrown into circulation and lodging in the brain.
However, factors other than a blood clot can block the fine blood vessels supplying the brain. Although rare, sometimes fragments of fat, a tumor or even a herniated disc can break off into the circulation and trigger a blockage that causes a stroke.
Hemorrhagic strokes can happen as a result of any condition that interferes with blood clotting. This can range from autoimmune conditions to genetic disorders to rat bait poisoning.
Your veterinarian will have a strong hunch that this is a stroke based on the animal’s history and presenting signs. Unless your vet has access to an MRI or CT scanner, it is difficult to make a sure diagnosis, but this is not always essential to start treatment.
Your vet may check for underlying conditions, such as high blood pressure, since treatment of the predisposing factor can reduce the chances of another stroke episode.
Although there is no specific treatment for a stroke, sometimes diuretics or corticosteroids are used to decrease swelling on the brain. However, this therapy is controversial and not proven to be beneficial.
Likewise, there is also a medication that maximizes the oxygen supply to the brain, which is desirable after a stroke. For patients with clotting problems, it is essential to stabilize their circulation and provide clotting factors, as they are at risk of internal bleeding with possibly catastrophic consequences.
Key to prevention is identifying underlying health problems, such as high blood pressure or heart disease, and treating these. By removing a trigger factor, we reduce the chances of another stroke.
- “Clinical and topographic magnetic resonance characteristics of suspected brain infarction in 40 dogs.” Garosi, McConnell, Platt et al. J Vet Intern Med, 20: 311–321.
- “Ischemic stroke in dogs and humans: A comparative view.” Garosi & McConnell. JSAP, 46: 521–529.
This pet health content was written by a veterinarian, Dr. Pippa Elliott, BVMS, MRCVS. It was last reviewed Nov. 4, 2015.