A stroke is the sudden and severe rupture, blockage or other compromise of a blood vessel in the brain that deprives the brain of its normal blood supply, causing inadequate oxygen delivery which in turn leads to loss of consciousness, paralysis and perhaps other symptoms depending upon the site and extent of brain damage. Strokes, medically referred to as infarcts or feline ischemic encephalopathy (FIE), are uncommon in cats. When they do occur, they tend to be focal rather than generalized in nature.
How Strokes Affect Cats
Adult cats of either gender and any breed can suffer from strokes. Interestingly, most feline strokes are diagnosed during the summer months in outdoor cats living in the northeastern United States or in southeastern Canada. The clinical signs and effects of stokes in cats are much different than those in people. In fact, the symptoms are so different that it was once thought that cats did not experience strokes. As new diagnostic technologies have developed, strokes are increasingly being diagnosed in cats. Feline strokes cause varying signs of acute-onset cerebral dysfunction, including depression, ataxia (uncoordination), head tilt, loss of balance, disorientation, confusion, uncontrollable circling, seizures, blindness, aggression, vocalization and/or other signs of altered mentation. While sudden in onset, these signs typically are non-progressive after 24 hours.
Causes of Strokes in Cats
When the brain does not receive a sufficient blood supply, it becomes deprived of oxygen and cannot function properly. This is called “ischemia.” Strokes occur from the blockage or breakage of blood vessels within the brain. This can be due to head trauma, ingestion of toxins such as rodenticides or underlying medical conditions such as diabetes mellitus, hypertension, hypothyroidism, hyperthyroidism, chronic renal failure, hyperadrenocorticism, liver disease and internal parasitic infections that result in aberrant migration of larvae into the middle cerebral artery. A stroke can occur when a fragment of fat or spinal cartilage becomes dislodged and trapped in the brain. Strokes can also occur in cats whose brains did not develop normally or in cats with inherited blood clotting disorders. The clinical signs of stroke often mimic those of other diseases, and advanced diagnostic tools normally are necessary to positively diagnose the cause of strokes in cats. In most cases, the actual cause of a stroke will never be definitively diagnosed. These are called “idiopathic” strokes. Regardless of the cause, early diagnosis and timely treatment are essential to a cat’s recovery. If you notice any signs of stroke in your cats, please take him or her to a veterinarian or emergency animal clinic immediately.
Preventing Strokes in Cats
Indoor cats are less likely to suffer from strokes than are cats allowed to go outdoors. Indoor cats are less prone to trauma and exposure to rodenticides. They also will not be exposed to botflies (Cuterebra), and thus a major cause of feline ischemic encephalopathy – aberrant larval migration - can be prevented by keeping cats indoors.
As long as the stroke is diagnosed and treated in a timely manner, a full recovery is possible, particularly if the stroke is caused by a focal ischemic event. The prognosis depends more upon the underlying cause of the stroke than upon the ischemic event itself. It can take weeks to months for cats to recover from the effects of a stroke. During this time, they typically require aggressive physical therapy and supportive outpatient care.