Stroke

Stroke in dogs is also known as a cerebrovascular accident, which means that the blood supply to the brain has suddenly been disrupted or destroyed. Stroke typically affects middle-age to geriatric dogs, but younger canines can have a cerebrovascular accident. There is no gender disposition. To continue normal function, the brain requires a constant supply of blood flow. With a stroke, this constant supply is reduced or cut off, causing symptoms such as loss of balance or blindness. With the advancement in testing and diagnostics, studies are showing that strokes in our pets are occurring more than previously thought. Breeds prone to a cerebrovascular accident are brachycephalic breeds (canines with wide, flat faces), Greyhounds, Cavalier King Charles Spaniel, and Miniature Schnauzer.

The onset of acute neurological signs can indicate a cerebrovascular accident. The severity of the signs will depend upon the region of the brain where the abnormality occurred, and how long the brain was deprived of the vital oxygen and blood supply. Symptoms will varying dramatically depending on the location of the stroke but may include:

• Loss of balance or falling
• Circling or weaving
• Loss of bladder or bowel control
• Paresis (weakness of voluntary movements)
• Loss of vision
• Head tilt Ataxia (inability to control movements)
• Change in behavior (for example, a calm dog becomes aggressive)
• Inability to recognize owner
• Seizure
• Sudden collapse

 

There are 2 main types of stroke:

Ischemic:

• There is lack of blood flow to the brain
• It is the most common type of stroke to affect dogs
• Clogging of an artery usually be a blood clot is called embolism
• A blood vessel may alA so spasm called constriction and loss of blood flow
• Restricted blood flow is seen on MRI

Hemorrhagic:

• Occurs with a broken blood vessel
• Usually results in blood leaking within the brain (intraparenchymal hemorrhage)
• Extravascular blood is seen on MRI

A TIA (transient ischemic attack), also called a ‘mini stroke’ is when the vascular compromise is minor and neurologic symptoms resolve within 24 hours.

 

 

Causes:

• Unknown or idiopathic is most common (thought to be related to weakening of the blood vessels in the brain, often associated with age.
• Secondary to metabolic problems (i.e. hypothyroidism, diabetes).
• Kidney disease resulting in loss of normal anticoagulants.
• High blood pressure
• Blood clotting disorders
• Heart disease
• Cancer anywhere in the body
• Certain medications (i.e. phenylpropanolamine / PPA)
• Systemic inflammatory diseases.

 

Treatment and Prognosis:

Treatment is largely supportive. If the stroke is not too big, the prognosis is generally good. A very large stroke can be devastating and cause permanent brain injury. A MRI help determine the long term prognosis. Most dogs start to show neurologic improvements within 24 hours. If the neurologic symptoms are worsening another problem other than stroke should strongly be considered. Low-dose Aspirin may be recommended if there is a predisposing risk factor for stroke. Supplementing with an Omega 3 supplement may also aid in the health of the blood vessels in the brain.