Until recently, strokes in dogs were considered extremely rare.
Dr Richard LeCouteur, professor of Neurology and Neurosurgery at the UC Davis School of Veterinary Medicine, explains how Magnetic Resonance Imaging is helping diagnose stroke in pets more often.
Dr Richard LeCouteur says the causes of stroke can be divided into two basic groups:
- ischemic stroke: an obstruction of the blood vessels, leading to infarction.
- haemorrhagic stroke: a rupture of blood vessel walls, leading to haemorrhage.
While most types of CVA (cerebrovascular accidents) seen in humans have been documented in dogs, Richard says recovery from cerebrovascular disorders in animals is more striking, since they have a less prominent pyramidal system.
Know the signs
Following a stroke, dogs will present a wide range of clinical signs that reflect the location and extent of the stroke within the brain.
“In general, a stroke is characterised clinically by a peracute or acute onset of focal, asymmetrical and non-progressive brain dysfunction. Worsening oedema may result in the progression of neurological signs for a short period of 24 to 72 hours in some affected dogs, however haemorrhage may be an exception to this description and be presented with a more progressive course,” explains Richard.
Clinical signs, which usually regress within four days, may vary from simple disorientation to death. Key signs indicating a unilateral stroke include:
- ipsilateral circling
- hemi-inattention syndrome (lack of recognition of sensory stimuli by one side of the brain and often manifested by eating out of only one side of the bowl, or turning to the wrong side in response to a name call)
- contralateral central blindness
- contralateral ataxia
- proprioception deficits
A concurrent medical condition was also detected in just over 50 per cent of dogs in one MRI study of dogs who had suffered stroke. “The most commonly diagnosed conditions were hyperadrenocorticism (Cushing’s disease), chronic kidney disease, hypothyroidism and hypertension,” says Richard.
It’s also important to note that clinical signs of stroke in people, such as balance or coordination problems, difficulty swallowing and loss of consciousness are rarely identified in dogs with stroke.
How are strokes treated?
While there’s sadly no known way to prevent stroke in dogs, or to predict if they might have one, Richard urges both owners and veterinarians to be prepared that recovery from a stroke takes time and patience, and may not be “complete” in all cases.
“The prognosis for stroke in dogs will depend on the severity of the cerebrovascular accident. But on the diagnostic side, the increased availability of MRI has been the single most significant advancement in the diagnosis of stroke in dogs,” says Richard. “Physical therapy as a way of optimising the rate and extent of recovery has also resulted in improved outcomes for dogs with stroke.”
Above everything, LeCouteur says veterinarians need to know two things about stroke in dogs:
- “The importance of searching for an underlying cause in a dog that presents with clinical signs that are consistent with a stroke, and in treating that underlying disorder when possible”; and
- “The importance of patience and persistence when managing a dog with stroke. Don’t give up too soon!”
Don’t miss Dr Richard LeCouter and other veterinary experts at FASAVA Congress, 11 – 14 August 2017.