Everything You Need to Know About Cerebrovascular Accidents (Strokes) in Dogs

October 26, 2020

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 hemorrhage.

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 and both in humans and dogs recovery is rapid. 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
disorientation
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
paralysis
seizures

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 realize 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 realize was significant or associated with their pet naturally aging.

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.

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, behavioral 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.

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 behavioral changes may take longer to resolve and 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 tumor, which triggered the stroke).

Risk factors for CVAs include:

heart disease (specifically congestive heart failure)
hypertension
blood clotting disorders
sepsis
malformations of the blood vessels
chronic kidney disease
brain tumor
heartworm
diabetes
Cushing’s disease
ingestion of poisonous substances

Hyperthyroidism has also been suggested as a risk factor, but the evidence is lacking to confirm this.

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.

In situations where a cause for the stroke cannot be determined then 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. Partly this is 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 ischemic 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 normalize with time, but it could take a week or more. I’ve had dogs live years after a stroke. Happy, healthy lives.”

Author: SOPHIE JACKSON

Link: https://pethelpful.com/dogs/Everything-You-Need-to-Know-About-Vascular-Accidents-Strokes-in-Dogs

If you are managing a pet who’s had a stroke and you need help with ideas and exercises, contact our Pet Teleconsultant Experts – they are some of the top rehab experts in the world. Get the help you need now without leaving home.

Everything You Need to Know About Cerebrovascular Accidents (Strokes) in Dogs

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