Animal Bites That Can Cause Stroke

An animal bite is an unusual cause of stroke. In some geographic regions and climates, a variety of poisonous creatures can thrive and pose a real threat to humans in the vicinity. Bites from some types of snakes, spiders, scorpions and even wasps can induce rapid physiological changes in the body resulting in neurological impairment and stroke.

Particular types of venom emitted from an animal bite or an animal sting possess chemical properties that disrupt normal blood clotting function, provoke excessive bleeding, stimulate hormone release and alter blood vessels in ways that lead to stroke.

Strokes that result from animal bites and stings are sudden and may be severe due to the sudden surge of venom released into the body of the victim.

Snake Bites

There are numerous case reports of snake bites resulting in a stroke. A viper snake, which can be found in many locations all over the world, has been repeatedly identified as a source of stroke in humans. The venom released into the bite victim’s circulation contains a number of toxins that produce a complex interaction with the human body.

Toxin effects include excessive bleeding, which triggers hemorrhage in multiple organs of the wounded individual. Sometimes, the toxins in the venom cause the opposite effect, resulting in blood clots in the brain or other structures of the body.

Other poisonous snakes, such as rattlesnakes, discharge venom into the system of the injured victim, which causes a combination of bleeding and blood clots throughout the body.

Proteins such as metalloproteinases, serine proteases, and C-type lectin, found in snake venom, have anticoagulation and pro-coagulation activity.

Effective treatment includes anti-venom as well as urgent medical assessment and care, including respiratory, cardiac and kidney support. Setbacks in effective treatment have been reported in cases when there is a delay in reptile identification and anti-venom administration.

Wasp Stings

Wasp stings rarely produce ischemic stroke. A case that reported in The Journal of Emergency Medicine described a patient who had experienced a documented ischemic stroke after he had been stung by a wasp. The stroke improved with administration of IV TPA. The patient had elevated levels of serum wasp immunoglobulin E and did not have any other stroke risk factors, which highly suggests that the wasp sting was the cause of the stroke.

Spider Bites

Spider bites are associated with muscle paralysis due to the direct action of neurotoxins on nerve and muscle transmission. Muscle paralysis can target any of the muscles throughout the body, including the muscles that support vital functions such as breathing and heart contraction. However, spider venom also can cause severe coagulation disorders, resulting in a stroke.

Blood clots induced by a poisonous spider bite can induce a stroke in any region of the brain, and may cause more than one stroke at a time. Similar to the medical management of venomous snake bites, medical care of a patient suffering from a stroke due to a toxic spider bite must include rapid and vigilant management of stroke symptoms coupled with an injection of anti-venom treatment.



The sting of some varieties of scorpions can cause a number of serious life-threatening consequences, including heart rhythm irregularities, muscle paralysis, and respiratory impairment. Severe abnormalities of heart function and blood pressure may trigger one or more hemorrhagic strokes. Additionally, the scorpion venom may directly interfere with the normal process that regulates bleeding and blood clotting, producing hemorrhagic or ischemic strokes in the brain. Scorpion stings induce the excessive activity of catecholamines, which are excitatory hormones. Over activity of catecholamines can induce strokes due extreme changes in blood vessel diameter, spasm of cerebral blood vessels, and abnormal heart rhythm reactions.

Call for Help Immediately

An animal bite can be perilous for the victim. Urgent medical attention is always necessary, as life-threatening symptoms may evolve rapidly. The indigenous animal species varies depending on the environmental locale and the climate, and emergency medical workers may be familiar with the dangers of native species and their effective treatments. Systemic medical care is often necessary to counteract the physiological effects of noxious components of the venom.  Often, administration of anti-venom is necessary to stop the sustained action of the poisonous material injected through a bite or a sting.


Association of ischemic and hemorrhagic cerebral stroke due to severe envenomation by the Sahara horned viper (Cerastes cerastes), Aissaoui Y, Hammi S, Chkoura K, Ennafaa I, Boughalem M, , Bulletin de la Société de pathologie exotique, August 2013

Bilateral posterior circulation stroke secondary to a crotalid envenomation: case report Vale TC, Leite AF, Hora PR, Coury MI, Silva RC, Teixeira AL, Revista da Sociedade Brasileiria de Medicina Tropical, March 2013

Ischemic Stroke After Wasp Sting, Kulhari A, Rogers A, Wang H, Kumaraswamy VM, Xiong W, DeGeorgia M, J Emerg Med. 2016 Aug 18.

Neurological effects of venomous bites and stings: snakes, spiders, and scorpions, Del Brutto OH, Handbook of Clinical Neurology, July 2013

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