We’re all too familiar with the prevalence of strokes among the human population, but most of us don’t know that this serious affliction can also affect our canine companions. Even many experts used to think that strokes in dogs were rare, especially as the symptoms can look the same as other causes of vestibular disease. But according to an article in a 2003 edition of the Journal of the American Animal Hospital Association, the use of MRIs has helped us realize that strokes are more common than previously thought.
What is a stroke?
Strokes occur when the blood supply to part of the brain is interrupted, causing damage to the brain. This happens either when a blood clot blocks off circulation (an infarct), or a blood vessel ruptures and causes bleeding into the brain (a hemorrhage). If the bleeding does not stop, further brain damage occurs with secondary edema and swelling. Since the skull stops the brain from expanding, swelling will lead to increased pressure on the brain. With enough pressure, tissue is destroyed, causing even more severe signs or death.
What are the causes?
Strokes are triggered by the things that cause the clotting or bleeding in the first place. These include:
- high blood pressure
- hyperviscosity syndromes
- cardiac disease
- kidney disease
- Cushing’s disease.
Signs and symptoms
Most commonly, the signs of stroke in dogs are the signs of vestibular disease. The vestibular system is responsible for balance, and includes the cerebellum at the back of the brain, the brainstem, and the nerves of the inner ears, as well as the position detectors in joints and tendons. Stroke, trauma, parasites, inflammation, or infection in almost any part of the system can cause a variety of symptoms, such as:
- dizziness (that may cause vomiting)
- inability to get up
- eyes flicking back and forth (nystagmus)
Strokes usually happen suddenly, but if there is slow bleeding, the signs may come on gradually. If damage is slight, the symptoms may be mild and only last a day or two. If the damage is worse, the signs are more severe and often include seizures.
If the stroke occurs in another part of the brain, the symptoms are often more subtle. They depend on which part of the brain is affected and how severe the damage is, and can include one or more of the following:
- sudden or gradual collapse
- inability to get up
- dazed look
- deviated eye.
- stiff or twisted neck.
Diagnosing the difference between stroke and other vestibular disease
Your veterinarian will look for a number of things before deciding whether or not your dog has had a stroke. A thorough physical exam and an x-ray of the skull help determine if there is a problem with the middle or inner ear. Two neurological signs that suggest inner ear inflammation are facial nerve paralysis (where the whole face droops on one side), or Horner’s syndrome (one eye that doesn’t close completely, with the third eyelid prominent).
Indications that the problem is in the brain include a dazed appearance, blindness, weakness or paralysis, and an inability to stand up, even if supported.
A general blood test, heartworm test, blood pressure check, and a urinalysis will reveal if the dog has kidney disease, hypothyroidism, Cushing’s disease, heartworm, or high blood pressure. Often, but not always, infection is also detectable this way. The physical exam can also detect if there’s a heart murmur, while a chest x-ray, EKG and perhaps an ultrasound will help determine what type of heart disease is present. A coagulation panel or anti-thrombin III level test will reveal any coagulation problems.
If the eardrum is bulging, there may be a need to carefully puncture it and collect fluid from the ear for culture. If a brain infection is suspected, an analysis of the cerebrospinal fluid can help; traces of blood would support the diagnosis of stroke.
The definitive test is a CT scan and/or an MRI. The CT scan is better in the first 24 hours, but an MRI is more useful after that.
How are strokes treated?
Due to the severity of this condition, the initial treatment is often best done with conventional medicine. Once the patient is stabilized, complementary modalities can be added to help with the control of chronic disease.
Initial treatment consists of IV fluids and intravenous corticosteroids to minimize brain swelling and support brain circulation. This is one of the few occasions where corticosteroids can be life-saving and help prevent permanent damage. Steroids given later on will not have nearly the beneficial effects of those given immediately.
Seizures should also be controlled by whatever means are available, including Valium, since prolonged seizures can cause further brain damage. Anti-seizure herbs usually do not work quickly enough to help at first, and can’t be given to a vomiting dog.
Acupuncture can be helpful for seizures and the rest of the stroke problems, both as an emergency measure and as a long-term treatment. Intravenous vitamin C is also useful initially, but in my experience its effects become less potent as time goes on.
As the patient recovers, acupuncture, antioxidants, Chinese herbs, and homeopathy continue to be helpful. Any other diseases contributing to the problem must also be addressed. Since these dogs are often profoundly affected, they may need to stay on a combination of conventional and complementary medicine for life.
Chances of recovery
Dogs recover from strokes much faster than people do. A dog with signs of vestibular disease that responds within two to three days has an excellent chance for recovery, but will often be left with a head tilt and some mild ataxia or dizziness. Some dogs may be left with seizures. If the cause is cancer, the seizures will usually increase in severity and frequency as time goes on.
If the stroke is in another part of the brain and involves extreme weakness or paralysis, the outlook is not as favorable, especially if the dog does not show some signs of getting stronger or more oriented within a week or two. I have found acupuncture to improve the chances of these patients.
About two-thirds of dogs who suffer a true stroke (not including vestibular disease from other causes that are mistaken for stroke), recover well. Of these, about a third will have further episodes. The biggest influence on their chances of recovery and risk of recurrence is the basic cause. If left untreated or uncontrolled, the chance of another stroke is much higher.
How can I prevent stroke in my dog?
Every dog over seven should have regular checkups and blood tests to detect diseases that can contribute to stroke. Antioxidants are an often-neglected nutraceutical that should be given to older dogs. Aspirin can help decrease clot formation, but should never be given if a previous stroke was the bleeding type.
Strokes can occur without warning and should be viewed as a veterinary emergency.
The symptoms can be upsetting to both you and your dog, but with prompt, professional treatment, the chances of recovery are greatly enhanced.