stroke

By Dr. Becker and comments by Diane Weinmann

It wasn’t until fairly recently that the veterinary community realized that just like humans, dogs and cats also suffer strokes — perhaps more frequently than we thought.

With increased use of magnetic resonance imaging (MRI) and computerized tomography (CT) scans in pets, strokes are being diagnosed more often. Fortunately, they are still a relatively rare occurrence in both dogs and cats.

What Exactly Is a Stroke?

In a nutshell, a stroke is a brain abnormality that occurs as the result of a disruption of the blood supply to the area. Circulating blood feeds oxygen and glucose to the brain. If a blood vessel becomes blocked or ruptures, the brain is deprived of those critical nutrients.

Most strokes are ischemic strokes caused by a blood clot (embolus) that develops in the circulatory system. The clot at some point dislodges and travels to a blood vessel that feeds nutrients to the brain, interrupting blood flow and causing surrounding tissue to die.

Strokes in dogs and cats can also result from bleeding in the brain (called hemorrhagic strokes) caused by the rupture of blood vessels or a clotting disorder. Hemorrhagic strokes are much less common in pets than ischemic strokes, and are usually the result of trauma or disease.

There’s also a non-brain related type of stroke called a fibrocartilaginous embolism (FCE). An FCE is a blockage in a blood vessel in the spinal cord. It’s often referred to as a spinal cord stroke.

There are several disorders that are associated with strokes in pets, including bleeding disorders, diabetes, hypertension, heart, kidney or thyroid disease, Cushing’s syndrome, Rocky Mountain Spotted Fever (a tick-borne disease) and cancer.

Internal parasites, tumors, ingestion of toxins, head trauma and high doses of steroids such as prednisone can also be contributing factors.

Symptoms to Watch For

The symptoms of stroke in dogs and cats depend on the location and extent of bleeding from cerebral arteries in the case of hemorrhagic stroke, or much more commonly, blockage of cerebral arteries in the event of an ischemic stroke. Symptoms typically come on suddenly and can include:

✓ Head tilt	✓ Weakness	✓ Abnormal eye movements (nystagmus) or eye positioning	✓ Seizures
✓ Difficulty walking or inability to walk	✓ Disorientation	✓ Loss of bowel control	✓ Collapse
✓ Loss of balance	✓ Persistent circling	✓ Inappropriate urination	✓ Coma
✓ Loss of coordination	✓ Sudden vision impairment	✓ Stupor	✓ Other sudden behavioral changes

Pet parents often remark that one minute their dog or cat was fine, and the next minute the animal was down and couldn’t get up. These episodes can last for just a few minutes, or for hours or even days.

When a pet recovers from one or more signs of a stroke in less than 24 hours, it’s usually considered a transient ischemic attack (TIA). Fortunately, TIAs typically don’t result in permanent brain damage.

Stroke Diagnosis

If your pet is exhibiting symptoms of a stroke, it’s important to get him to your veterinarian or an emergency animal hospital right away. Since there are many unrelated disorders with stroke-like symptoms, quick action and a proper diagnosis are critical.

For example, vestibular disease in geriatric dogs is often mistaken for stroke. The vertigo caused by the disease can be particularly intense in older dogs with symptoms of nausea, difficulty or complete inability to stand up, head tilt, nystagmus and circling.

Your veterinarian will need to run a variety of diagnostic tests, including bloodwork and a urinalysis, to rule out other possible causes for your pet’s symptoms.

If the problem isn’t obvious from initial test results, additional diagnostics will be required to look for evidence of a stroke, including an MRI or CT scan of your pet’s brain.

Your pet may be sent to a veterinary specialist (neurologist) for these scans, and may need to be hospitalized for the procedures. CT and MRI scans are the gold standard for diagnosing strokes in pets, including whether the stroke is ischemic or hemorrhagic. Other tests that may be needed include:

Arterial blood gases to assess oxygenation of blood
Coagulation profiles to assess blood clotting
X-rays of the skull to look for evidence of trauma or fractures
Electrocardiogram (ECG) to evaluate heart rhythm
A spinal tap to evaluate cerebrospinal fluid

Treating a Pet Who Has Had a Stroke

If your pet’s symptoms are severe, she may need to be hospitalized to receive oxygen and fluid therapy and other supportive care.

Treatment of stroke patients is focused on minimizing brain swelling and tissue damage, maximizing oxygen flow to the brain, identifying and treating the underlying cause of the stroke if possible and physical therapy.

Initial treatment typically involves intravenous fluids and IV corticosteroids to control brain swelling and support blood circulation to the brain.

This is a situation in which giving corticosteroids immediately can be life-saving and help prevent permanent damage. Seizures must also be controlled with conventional drugs to prevent further brain damage. Anti-seizure herbs usually do not work quickly enough to help during the initial crisis, and are difficult to administer to a vomiting dog.

The neurologic symptoms of a stroke gradually resolve on their own as the animal’s body re-establishes normal blood flow to the brain and swelling resolves. During this period, acupuncture, antioxidants (SOD and astaxanthin), Chinese herbs and homeopathy can be very beneficial.

The most crucial supplement to add for these patients, in my opinion, is nattokinase, which can also help prevent additional strokes from occurring. The brain has the ability to recover given time. As always, early diagnosis and treatment can dramatically improve your pet’s chances for a full recovery.

Pets who survive the first few days following a stroke have a good chance for a full or nearly full long-term recovery when the underlying cause can be identified and either eliminated, or successfully controlled.

My personal experience was a horse who seemed to have a stoke and could not longer see. He was walking weirdly and bumping into things, leaning against his stall wall and seemed very confused. I started doing several healing touch for animal techniques on him about 4 times per week and within less than a month he was walking normally and he could see again. Did I help, I pray that was true!

Strokes in Cats

By Dr. Justine A. Lee, DVM, DACVECC and http://www.askthecatdoctor.com/feline-stroke.html

There are two types of strokes in cats:

(1) Ischemic – the blood supply to an area of the brain is cut off

(2) Hemorrhagic – the wall of a blood vessel is damaged and blood leaks out of it into an area of the brain

In either case, an area of the cat’s brain can be deprived of oxygen or damaged from pressure and a stroke follows.

It’s scary to see your cat suddenly not be able to walk, look drunk, fall over to his or her side, have a head tilt, or act neurologically inappropriate (e.g., seizure). Other signs that look like “acute strokes” in cats include:

sudden imbalance
falling over to the side
not being able to walk
vomiting
nausea
inappetance (who wants to eat when they are nauseated?)
rolling or circling to one side
nystagmus (abnormal eye movement)

When this happens, there are four primary causes:

an ischemic event secondary to hypertension
a life-threatening blood clot called a “saddle thrombus”
vestibular disease
a brain tumor

Keep in mind, however, that these symptoms are the symptoms of so many other diseases. Just because your cat has some of all of the above symptoms does not mean she has had a feline stroke. All of the symptoms are serious so an immediate trip to the veterinarian is essential. I know that I say this in almost every article I write, BUT the earlier a diagnosis is made, the better the outcome.

Possible Causes of a Feline Stroke

Trauma
Anything that interferes with the clotting ability of the blood
Blood clot
Heart Disease
High Blood Pressure
Hyperthyroidism
Diabetes
Kidney Disease

In older cats, secondary hypertension (high blood pressure) may be a result of chronic kidney disease, hyperthyroidism (an overactive thyroid gland), or even cardiac disease. With uncontrolled hypertension (in other words, if it wasn’t previously diagnosed or isn’t responding to blood pressure medication called “Norvasc,” or amlodipine), an acute ischemic event can occur. This means that lack of blood flow occurs in a region (typically in the brain or spinal cord), and results in neurologic abnormalities. Thankfully, ischemic events often respond well to symptomatic supportive care and anti-hypertensive blood pressure medications. However, these ischemic events can leave permanent neurologic defects in your cat like wobbliness, a head tilt, etc.

The second cause may be due to a blood clot (commonly called a “saddle thrombus”). This is typically due to severe heart disease, and may result in severe pain. Due to the complexity of this disease, which typically has a poor prognosis, I’ll cover it in a separate blog.

The third cause is similar to old dog vestibular disease in dogs. While cats rarely get acute vestibular disease (like a tinnitus in humans), it can occur acutely for several reasons: from ear infections; from a tumor in the ear; from sticking aQ-tip too far down in your cat’s ear; cleaning your cat’s ear with liquid ear medications; from old trauma or underlying metabolic problems; or just simply for no reason at all (we call this reason idiopathic vestibular disease in cats, which is a fancy way of saying that we have no idea what caused it!).

Lastly, underlying cancer or infections in the brain or spinal cord can cause these signs. When in doubt, a CT or MRI may be necessary to diagnose what’s going on. But before potentially euthanizing for an “acute stroke,” make sure to check with a veterinarian. Simple tests like a blood pressure, thyroid level, kidney test, and chest x-rays are a great place to start to help rule out some of the more benign versus malignant causes.

Simple tests like a blood pressure, thyroid level, kidney test, and chest x-rays are a great place to start to help rule out some of the more benign versus malignant causes.

However, for a definitive diagnosis, CT or MRI is needed. In reality, most cat owners do not have this type of testing capability in their area or cannot afford it, so in many, many cases, the diagnosis of a feline stroke is made on the basis of history, physical exam and the ruling out of other diseases through laboratory tests and radiology.

Treatment of a Cat Stroke

Treatment for a cat stroke is most often supportive (warmth, food, care) although IV fluids may be needed as well as anti-inflammatories, seizure medications, and other treatments as determined by the cat’s needs. If an underlying cause has been determined, then treatment will also be directed at that cause.

For example, if feline heart disease has been discovered, then heart medications, dietary changes, and other treatments directed at the underlying heart disease will be prescribed. If the cat has an elevated thyroid level and has been determined to have feline hyperthyroidism, then medication for hyperthyroidism in cats will be prescribed.

However, in many cases, an underlying cause is not found and treatment will involve time, patience, and support. Keeping your cat well hydrated, well fed, warm and comfortable goes a long way toward recovery.