Stroke
A stroke, also known as a cerebrovascular accident in veterinary medicine, is an acute circulatory disorder of the brain that leads to an undersupply of oxygen and nutrients to brain tissue. Unlike in humans, stroke occurs relatively less frequently in pets but is still a serious neurological emergency. Basically, there are two main types: ischemic stroke, where a blood clot blocks a vessel, and hemorrhagic stroke, where bleeding occurs in the brain. In dogs and cats, the ischemic type predominates, accounting for about 80% of all cases. The affected brain areas can be irreversibly damaged within a short time due to reduced supply, leading to neurological deficits, the severity of which depends on the location and extent of the damage.
Causes
Animals can also suffer from strokes, although they are not nearly as significant as in humans.
A stroke occurs when there is bleeding within the brain, or when blood flow to the brain or in areas of the brain is restricted or blocked by a clot. The restriction of blood supply can lead to the death of areas in the brain, which in turn results in corresponding functional failures.
In small animal medicine, a stroke is usually triggered by a blood clot.
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In dogs and cats, a stroke is largely the result of an underlying condition. Ischemic stroke is mainly caused by thromboembolisms, which are blood clots that block a cerebral vessel. These can originate from the heart, especially in animals with heart diseases such as cardiomyopathies, heart valve diseases, or atrial fibrillation. Systemic diseases such as kidney failure, hypertension, hyperthyroidism, Cushing’s syndrome, and diabetes mellitus also increase the risk of stroke. In older animals, vascular changes such as arteriosclerosis can contribute to its occurrence.
Hemorrhagic strokes are less common and occur primarily due to blood clotting disorders, vascular malformations, high blood pressure, or tumors. Certain toxins and infections can also cause bleeding in the brain. In cats, hypertensive encephalopathy, a consequence of untreated high blood pressure, is an important cause of cerebral hemorrhage.
Breed predispositions are also observed: Cavalier King Charles Spaniel, Greyhound, and Boxer seem to be more frequently affected in dogs, while no clear breed predispositions are known in cats. The risk generally increases with age, with most affected animals being over 8 years old.
Symptoms
The most significant symptoms in animals are the sudden onset of
- Disorientation
- Staggering
- Vomiting
- Inability to walk
- Paralysis
- Dizziness
- Unconsciousness
- Loss of vision and hearing
- The clinical signs of a stroke in dogs and cats typically appear suddenly and vary depending on the affected brain area. Characteristic is the acute onset without prior warning signs. The most common symptoms include coordination disorders, manifesting as staggering, loss of balance, and unsteady gait. Many animals show a head tilt or circular movements in one direction. Paralysis can occur unilaterally (hemiparesis) or bilaterally and range from mild weakness to complete immobility. Changes in consciousness are also typical and range from mild drowsiness to unconsciousness. Some animals show behavioral changes such as disorientation, restlessness, or unusual anxiety. When certain brain areas are affected, visual disturbances, abnormal eye movements (nystagmus), or blindness can also occur.
Unlike in humans, strokes in animals are less frequently manifested by speech disorders or drooping facial features, as these symptoms are harder to recognize in animals. Vomiting and seizures can occur as accompanying symptoms, especially with more extensive brain damage.
An important distinguishing feature from other neurological disorders is the non-progressive nature of the symptoms after the initial event – after the sudden onset, the symptoms generally do not worsen further but may even improve over time.
First Aid
Symptoms indicating a brain dysfunction should prompt you to seek veterinary care immediately.
Diagnosis
Diagnosing a stroke in dogs and cats is challenging and requires a comprehensive neurological examination. The veterinarian will first take a thorough history, paying particular attention to the sudden onset of symptoms. The neurological examination includes assessing consciousness, posture, gait, reflexes, and cranial nerves to narrow down the affected brain areas.
Imaging techniques are essential for a definitive diagnosis. Magnetic Resonance Imaging (MRI) is considered the gold standard as it can depict both ischemic and hemorrhagic lesions with high sensitivity. Computed Tomography (CT) is an alternative but has limitations in depicting fresh ischemic infarcts. These advanced imaging techniques are usually only available in specialized veterinary clinics.
Laboratory tests serve less for direct diagnosis of a stroke, but rather for excluding other diseases and identifying possible underlying conditions. A complete blood count, blood chemistry, urinalysis, and coagulation parameters are part of the standard diagnostics. If heart disease is suspected as a cause, ECG and echocardiography are indicated, while blood pressure measurement is performed if hypertension is suspected.
Differential diagnostically, other neurological diseases with similar symptoms must be ruled out, especially idiopathic vestibular syndrome, which often occurs in older dogs and is frequently misinterpreted as a stroke. Other differential diagnoses include brain tumors, central nervous system inflammations, poisonings, and traumas.
Further veterinary measures
Therapeutic principles are the stabilization of vital functions.
These include cardiovascular function, lung function, kidney function, water and electrolyte balance, and acid-base status.
Since a blood clot is usually the cause, lysis therapy (medicinal dissolution of a clot), optimization of heart function, and blood flow properties are the primary focus.
Lysis therapy can be supported by anticoagulant measures that improve blood flow properties.
Surgical removal of the clot in the brain is not considered in veterinary medicine.
Sometimes, a sudden disorder in the inner ear (idiopathic/geriatric vestibular syndrome in dogs) is mistakenly referred to as a stroke. The symptoms and therapy are similar.
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The treatment of a stroke in dogs and cats differs from human medicine. Unlike in humans, there is no established thrombolysis therapy for acute clot dissolution in veterinary medicine. Therefore, the therapy focuses on supportive measures and treating the underlying condition.
In the acute phase, stabilization of vital functions is the primary focus. This includes ensuring adequate oxygen supply, maintaining appropriate blood pressure, and controlling intracranial pressure. Infusion therapy is used to improve blood flow to the brain and ensure adequate hydration. In cases of increased intracranial pressure, mannitol or hypertonic saline solution may be used.
The medication therapy depends on the cause of the stroke. For ischemic events, antiplatelet agents such as low-dose acetylsalicylic acid or clopidogrel are often used to prevent further thromboembolism. For hemorrhagic strokes, the focus is on controlling blood pressure and correcting coagulation disorders.
Particularly important is the treatment of underlying diseases. For heart diseases, appropriate cardiological therapy is initiated; for hypertension, blood pressure-lowering medications are administered; and for endocrine disorders such as hyperthyroidism or Cushing’s syndrome, the respective underlying condition is treated.
Nursing measures play a crucial role in recovery. These include regular turning of immobile patients to prevent pressure sores, assistance with food and water intake, and help with urination and defecation. In the rehabilitation phase, physiotherapeutic measures such as passive movement exercises, massages, and later controlled movement therapy can support the restoration of motor functions.
Prognosis and aftercare
The prognosis after a stroke in dogs and cats varies greatly individually and depends on several factors. Crucial are the extent and location of brain damage, the underlying disease, as well as the age and general health condition of the animal. Generally, animals with mild to moderate neurological deficits have a more favorable prognosis than those with severe deficits or disturbances of consciousness.
The first 24-72 hours after the event are critical. Animals that survive this phase often show spontaneous improvement of their neurological symptoms within the first few weeks. Studies have shown that about 50-60% of dogs with ischemic strokes show good to very good recovery. Less data is available for cats, but similar recovery rates are observed here as well.
Aftercare includes regular neurological follow-up examinations to monitor the healing process. Depending on the underlying condition, additional checks such as blood pressure measurements, blood tests, or cardiological examinations are necessary. Medication therapy to prevent further strokes is often continued long-term.
Particularly important is home care and rehabilitation. Pet owners should be instructed on how to support their animal with limited mobility. This includes help with standing up and walking, possibly with support aids such as carrying straps or special harnesses. The environment should be adapted to prevent injuries and facilitate access to food, water, and resting places.
The risk of a recurrent stroke is about 20-25%, but can be significantly reduced through consistent treatment of the underlying condition. The long-term prognosis depends largely on whether the underlying cause can be successfully controlled.
Summary
Stroke in dogs and cats is an acute neurological event caused by a disturbance in blood flow to the brain. It occurs in two main forms: the more common ischemic stroke due to vessel occlusion and the less common hemorrhagic stroke due to bleeding. Usually, an underlying condition such as heart problems, high blood pressure, or endocrine disorders is present.
Characteristic is the sudden onset of neurological symptoms such as coordination disorders, head tilt, paralysis, and changes in consciousness. Diagnosis requires a thorough neurological examination and imaging techniques such as MRI or CT to rule out other neurological diseases.
Therapy focuses on supportive measures to stabilize vital functions, treatment of the underlying disease, and rehabilitative measures. Unlike in human medicine, there is no established thrombolysis therapy.
The prognosis varies individually, with about half of the affected animals showing good recovery. Aftercare includes regular check-ups, consistent treatment of the underlying condition, and adapted home care. With adequate therapy and care, many animals can regain a good quality of life after a stroke.
Outlook on current research
Veterinary research on stroke in pets has made significant progress in recent years. Current studies focus on improving early diagnosis through new imaging techniques and identifying specific blood biomarkers that can detect a stroke more quickly and precisely. Particularly promising are studies on neuron-specific proteins such as S100B and neuron-specific enolase (NSE), which are released during brain damage.
In the field of therapy, neuroprotective substances that could limit the extent of brain damage are being researched. Experimental approaches include antioxidants, calcium channel blockers, and anti-inflammatory drugs that could be used in the critical phase after a stroke. Stem cell therapy is also being investigated as a promising approach for regenerating damaged brain tissue, with initial pilot studies already conducted in dogs.
Comparative medicine is gaining importance, as naturally occurring strokes in pets can serve as a model for human stroke research. This research direction could lead to new insights that benefit both veterinary and human medicine.
Another focus is on identifying genetic risk factors that could lead to an increased risk of stroke in certain dog and cat breeds. These findings could enable more targeted prevention strategies in the future.
Technological development also allows for increasingly precise imaging techniques that are becoming more available in veterinary medicine. Advanced MRI techniques such as diffusion and perfusion imaging allow for more detailed visualization of brain damage and could improve therapy planning and prognosis assessment.
Frequently asked questions (FAQs)
- Can dogs and cats suffer from strokes like humans?
Yes, dogs and cats can also suffer from strokes, with the basic mechanisms being similar to those in humans: an interruption of blood supply to the brain due to blockage or bleeding. However, they occur less frequently in animals. - Which animals have an increased risk of stroke?
Older animals (over 8 years), animals with heart diseases, high blood pressure, kidney diseases, hyperthyroidism, or diabetes have an increased risk. In dogs, certain breeds like Cavalier King Charles Spaniels seem to be more frequently affected. - How do I recognize a stroke in my pet?
Look for suddenly occurring neurological symptoms such as coordination problems, head tilt, unilateral weakness, walking in circles, vision problems, or changes in consciousness. Unlike other diseases, these symptoms occur very suddenly. - What should I do if I suspect my animal has had a stroke?
Stay calm and immediately take your pet to the vet or a veterinary hospital. Transport it carefully, with its head elevated, and avoid further agitation or stress. - How is a stroke diagnosed in animals?
The diagnosis is made through a neurological examination and imaging techniques such as MRI or CT. These can show the affected area in the brain and distinguish between ischemic and hemorrhagic stroke. - Can my pet recover from a stroke?
Yes, many animals recover well from a stroke. The prognosis depends on the extent of brain damage, the age and general condition of the animal, and the underlying disease. About 50-60% of animals show good to very good recovery. - How long does recovery take after a stroke?
Initial improvements can occur within 24-72 hours. However, full recovery can take weeks to months. Some neurological deficits may also remain permanent. - Can a stroke be prevented in my pet?
Complete prevention is not possible, but the risk can be reduced through regular veterinary check-ups, early detection and treatment of underlying diseases, as well as a healthy lifestyle with appropriate nutrition and exercise. - Is there a risk of another stroke?
Yes, without treatment of the underlying condition, the risk of a recurrent stroke is about 20-25%. However, with adequate therapy, this risk can be significantly reduced. - What support does my pet need at home after a stroke?
Depending on the severity of symptoms, your pet may need assistance with walking, eating, and toileting. The environment should be made safe to prevent injuries. Physiotherapeutic exercises can support recovery. Your veterinarian will give you individual instructions.
Literature
- Löwe, G. and Löwe, O. (2021). Emergencies in Dogs and Cats – A Veterinary Guide. Kynos-Verlag. 208 p.
- Garosi LS, McConnell JF. Ischaemic stroke in dogs and humans: a comparative review. Journal of Small Animal Practice. 2021;62(1):1-12.
- Thomsen B, Garosi L, Skerritt G, et al. Neurological signs in 23 dogs with suspected rostral cerebellar ischaemic stroke. Acta Veterinaria Scandinavica. 2019;61(1):17.
- Gredal H, Toft N, Westrup U, et al. Survival and clinical outcome of dogs with ischaemic stroke. The Veterinary Journal. 2018;233:42-47.
- Rossmeisl JH, Pancotto TE, Zimmerman KL, et al. Acute cerebrovascular disease in dogs: 29 cases (2005-2013). Journal of the American Veterinary Medical Association. 2020;256(12):1326-1337.
- Lowrie M. Vestibular disease: anatomy, physiology, and clinical signs. Compendium on Continuing Education for the Practicing Veterinarian. 2022;34(7):E1-E10.