Sophie Jackson is a dog lover and trainer living in the UK. She competes in agility and obedience with her four dogs.
The term 'stroke', when used in relation to dogs, generally refers to a vascular accident (sometimes cerebrovascular accident or CVA) that has occurred within the body and has affected the brain.
For many years vets thought that strokes in dogs were rare, but recent advances in veterinary medicine have changed this perspective and we are now beginning to learn how common canine strokes really are.
The word 'stroke' is sometimes misused to apply to conditions that are not CVAs, and this can cause confusion for pet owners. Understanding what a stroke is and what it is not, and how it affects dogs, helps us to know how to treat our beloved pets and improve their chances of survival.
Research is still ongoing to understand what causes CVAs and how to best treat them in dogs. There is still a lot to learn about this condition, but the good news is a CVA is not the end of the world for your dog and many recover well from them.
In fact, minor CVAs can go unnoticed as the signs can be extremely subtle and the dog recovers without veterinary treatment.
What Is a Cerebrovascular Accident?
When a dog has a CVA, it means that something has occurred to impair the normal function of the brain. There are two main ways this can happen, either there is an obstruction of a blood vessel (typically caused by a clot) or a blood vessel in the brain bursts and bleeds, causing a haemorrhage.
When either of these things occurs, the flow of oxygen and nutrients to the brain is impeded and brain cells begin to die. This results in brain damage and the visible symptoms of a stroke.
In humans, 85% of strokes are ischaemic, meaning they are caused by a clot preventing blood circulating properly. Only 15% of strokes are hemorrhagic, meaning they are caused by blood vessel bleeding. We do not yet have enough research to indicate if similar figures exist for dogs, but it would seem a likely possibility.
The severity of a stroke depends on how long the blood flow is disrupted. When the blood supply is only stopped briefly, the damage is not so bad. Recovery is rapid in both humans and dogs. This is known as a TIA (Transient Ischemic Attack) or mini-stroke. Though the incidence of TIAs in dogs has not been studied, as the symptoms are mild and often not noticed or mistaken by the owners for something else, it is thought by some vets that they do occur in canines.
In cases where the blood flow to the brain is disrupted for longer, the symptoms of a stroke are more severe and can result in paralysis or turning in circles.
With advances in technology, notably Magnetic Resonance Imaging (MRI), it is now possible to identify with certainty when a dog has had a stroke, the area of the brain affected, and the severity.
Spotting the Symptoms
While in people the symptoms of a stroke are often dramatic, in dogs they can be subtle and may be overlooked or confused for something else.
Common symptoms include:
- head tilt
- lack of appetite (caused by feeling nauseous)
- loss of balance
- loss of vision (possibly only on one side)
- walking in circles
- eyes flicking from side-to-side
- behavioural changes (whining, seeking attention, aggression)
- loss of basic training which could include incontinence
- difficulty learning new things or struggling to focus on a task (most noticeable in dogs that compete in a dog sport which requires regular training)
- seeming 'spaced out' or in a daze
- dragging a hind leg or limping on a front leg
The type of symptoms a dog will display after suffering a CVA depends greatly on the severity of the stroke, what has caused it and where it occurs in the brain. Many owners only realise their pet is unwell when it suffers a severe stroke with dramatic symptoms, such as seizures and paralysis. They may later recall their pet having other, milder symptoms of stroke before this incident, which at the time they did not realise was significant or associated with their pet naturally ageing.
CVA symptoms are often confused with Vestibular Disease, which causes a number of the same symptoms (head tilt, loss of balance, turning in circles). The vestibular system is responsible for balance and is located in the brain and the inner and middle ear.
Confusingly, a CVA can actually trigger a vestibular problem if it affects the portion of the brain associated with the vestibular system and sometimes Vestibular Disease is referred to as a canine stroke, which is incorrect. Vestibular Disease can occur due to an ear infection, head trauma, a tumour, or sometimes for no obvious reason. It is generally self-resolving without treatment and is not fatal, although it may be an indication of something else that could be life-limiting.
In contrast, CVAs are more serious as without treatment they can become progressively worse and result in the death of the dog.
Other conditions that could be confused with CVAs due to the symptoms are spinal problems (dragging the hind leg), arthritis or muscle sprain (front leg limp), epilepsy (seizures, behavioural changes, disorientation) and poisoning by something toxic.
Only a vet can determine if a dog has truly suffered a CVA, as this requires specific tests not only to rule out other conditions but potentially to spot where the stroke has occurred within the brain.
How Is a CVA Diagnosed?
Since the symptoms of a CVA can mimic many other conditions, it is important to seek veterinary advice at once if you suspect your dog has had a stroke. Diagnosis is partly dependent on ruling out other possible illnesses before your dog is confirmed as having a stroke. Blood and urine samples are taken to check for underlying conditions.
Occasionally, dependent on the type of stroke, it is possible to see evidence for it during a physical exam. For instance, in a hemorrhagic stroke where a blood vessel has burst and bled into the brain, it may be able to see evidence of this if the blood has haemorrhaged behind the eye causing temporary blindness.
Unfortunately, for most cases of stroke, the only reliable way of confirming a CVA has occurred is by using an MRI machine to scan the brain. However, MRIs are expensive and usually have to be performed at a specialist vet, which puts them out of the budget of many owners.
Dogs that have one stroke may go on to have another and each one they have tends to be more severe. This is another factor in diagnosing a CVA, though it is not so helpful if your dog has only had a single stroke.
Treatment and Recovery
Dogs recover better from strokes than people and usually in a faster time. Minor strokes that do not cause paralysis or seizure can resolve in a week, however, things such as behavioural changes may take longer to resolve. In some cases, they may be permanent.
As with people, the initial few hours and days after a stroke has occurred are critical to determining recovery. The swifter the improvement the more chance of a full recovery, but this is very dependent on how much damage was done, what was affected in the brain and whether there is an underlying condition (such as a brain tumour, which triggered the stroke).
There is no treatment for a stroke, other than to take care of the pet during its recovery and to treat any potential side-effects, such as nausea. A dog that has suffered a CVA should have a thorough medical assessment, including blood tests and heart scan, to determine if there is an underlying cause for the stroke which needs to be treated.
Risk factors for CVAs include:
- heart disease (specifically congestive heart failure)
- blood clotting disorders
- malformations of the blood vessels
- chronic kidney disease
- brain tumour
- Cushing's disease
- ingestion of poisonous substances
Unfortunately, in around 50% of cases, it is impossible to find an underlying trigger for the stroke.
Life After a Stroke
The long-term outcome for a dog that has suffered a stroke is dependent on a number of factors, such as the severity and whether an underlying cause was found to be associated with the CVA.
Some conditions that can trigger a stroke are in themselves life threatening, such as in the case of a brain tumour or kidney disease. In these cases, palliative care may be the only option for the dog and their life expectancy will not be great.
Other causes of stroke can be managed with medication, and as a result, the outlook for the dog is more promising. With the correct treatment not only will the underlying disease be controlled, but the risk of further strokes is minimised.
In situations where a cause for the stroke cannot be determined, the outcome for the dog is far more complicated. There is a high possibility of further strokes occurring, these may be minor or major events, but each will do a little more damage to the brain and may lead to permanent disability in the dog.
There is little the owner can do to prevent further CVAs, but being vigilant of the pet and taking them to the vet the instant they notice potential signs of a stroke will help.
Only a handful of studies have been done into the long-term survival rate of dogs that suffer a CVA. This is partly due to a lack of dogs being diagnosed with the condition.
A study published in 2012 looked at 22 dogs that had been diagnosed by MRI with ischaemic strokes.
- Five dogs (23%) died within 30 days of the stroke.
- In those dogs that survived beyond 30 days, the prognosis was better, with an average life expectancy of 505 days (nearly 17 months).
- Four dogs (18%) lived longer than this and were still alive at the time the study concluded.
- The study found that in dogs that survived beyond 30 days there was a high probability of another stroke 6-17 months after the first.
It is not all doom and gloom, however. Veterinarian Dr Todd Bishop states, "I'd say as many as 75% [of dogs] improve or normalise with time, but it could take a week or more. I've had dogs live years after a stroke. Happy, healthy lives."
While there is still a lot we don't know about strokes in dogs, the general picture is positive and many dogs survive even quite severe strokes and return to a normal life.
This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.