Introduction
A “stroke” is the sudden and severe attack or rupture of a blood vessel in the brain that deprives parts of the brain of their normal blood supply, causing loss of consciousness, paralysis and perhaps other symptoms depending upon the site and extent of the brain damage. In dogs, strokes occur when the normal blood supply to the brain has been compromised, and they occur rarely. The effects of a “stroke” are caused by the lack of normal oxygen delivery. The symptoms and effects of stroke in dogs include: head tilt, difficulty walking, uncontrollable circling, sudden loss of vision and bowel control and sudden behavioral changes. While strokes in dogs are uncommon, there are a number of conditions that can predispose a dog to having a stroke.
Causes of Stroke in Dogs
There is no overall genetic, age, sex or breed predisposition in dogs to having a stroke. Some reports suggest that Cavalier King Charles spaniels are more commonly affected by cerebellar infarcts, possible due to the conformation of their skull.
When they do happen, strokes in dogs most commonly are caused by interruption of oxygen delivery to brain tissue due to some underlying medical condition, including perhaps accidental injury or poisoning. Ischemic strokes occur when the blood supply to the brain has been reduced, and hemorrhagic strokes occur when a vessel within the brain breaks. The clinical signs of stroke often mimic those of other diseases, and advanced diagnostic tools are needed to positively diagnose the cause of stroke in dogs.
The most common underlying medical conditions which can lead to stroke in dogs include brain tumors, Cushing’s disease, diabetes, heart disease, kidney disease and thyroid disease. In some rare cases, internal parasites can cause a stroke to occur. A stroke can occur when a fragment of fat or spinal cartilage becomes dislodged and trapped in the brain. Strokes can also occur in dogs whose brains did not develop normally or in dogs with inherited blood clotting disorders. Accidental injuries involving a strong blow to the head can also cause a stroke, and poisons such as rodenticides have been known to cause strokes in dogs as well.
In most cases, the actual cause of a stroke will never be definitively diagnosed. These are known as “idiopathic strokes”. Regardless of the cause, early diagnosis and timely treatment are essential to a dog’s recovery. If you notice any signs of stroke in your dog, please take him or her to a veterinarian or emergency animal clinic immediately.