Symptoms and pathological changes of animal snake venom poisoning

Snake venom poisoning is caused by acute toxic diseases characterized by hemolysis, sensory nerve peripheral paralysis and shock when the venom is bitten by poisonous snakes. It can occur in all kinds of animals and is common in grazing animals and dogs.

1. Clinical symptoms

Most animals are bitten by poisonous snakes in the lips, nose, face and lower limbs. Horses, cattle and sheep are bitten by snakes in the vicinity of the tarsal joint or ball joint, while pigs and dogs are mostly in the extremities and nasal ends. The closer the bite site is to the rich part of the central nervous system and blood vessels, the faster the onset and the more serious the symptoms. Different kinds of animals have different responses to snake venom after being bitten by snakes. equine animals are the most sensitive, followed by ruminants, and adult pigs are the least sensitive because they are rich in subcutaneous fat, which affects the speed of venom entering the bloodstream. Piglets often die of poisoning within 1 hour after being bitten. After the animal is bitten by a poisonous snake, because the snake's teeth are very small and the wound is not large, it is not easy to be found, but its symptoms appear quickly and the disease develops quickly. The severity of symptoms is also related to the type and detoxification of venomous snakes. After poisoning, the animals mainly showed local symptoms and systemic symptoms.

Local symptoms of ⑴: local redness, swelling, pain and bleeding caused by snakebite. When biting the head, the lips, nose, cheek and submandibular glands are extremely swollen, animals are restless, and the conjunctiva is flushed. In severe cases, the upper and lower lips cannot be closed, nasal mucosa is swollen, nasal meatus is narrow, breathing is difficult, and conjunctiva is swollen. When bitten limbs, local swelling, hot pain, the affected limb can not bear weight, stand on the tip of the hoof to the ground, or even lift the diseased limb, exercise cripple, sometimes lying on the ground.

⑵ systemic symptoms: due to the different effects of the toxins contained in venomous snakes, they mainly show the symptoms caused by nerve poison, blood poison and mixed poison.

⑶ neurotoxic symptoms: silver ring snake, gold ring snake and sea snake all belong to nerve poison. After being bitten by this kind of venomous snake, the local reaction is not obvious, the blood is less, the redness, swelling, heat and pain and other local symptoms are mild, but after being bitten by the cobra, the local tissue is necrotic and fester, and the wound is not easy to heal for a long time. When toxins spread from the blood and lymph, sharp systemic symptoms usually occur within hours of a bite. First of all, the muscles of the extremities are paralyzed and weak, lying on the floor, groaning in pain, followed by dysphagia, foaming at the mouth, dilated pupils, arrhythmia, irregular pulse, dyspnea, vomiting, sweating all over the body. Finally, the whole body muscle tremor, and even convulsions, blood pressure drop, shock, coma, and finally died of respiratory muscle paralysis, asphyxiation.

⑷ heart damage and blood clotting disorders: viper, five-step snake, bamboo leaf green snake, tortoise shell flower snake and so on can produce blood circulation poison. After the animal was bitten, the local symptoms were serious, obvious swelling, severe pain, bleeding, extreme edema, local color darkening; local lymph node enlargement, subcutaneous bleeding, some blisters, blood blisters, and even tissue ulceration and necrosis. The swelling extends rapidly to the upper extremities and generally spreads to the entire head and neck, or to the forelimbs and waist and back after 6 to 8 hours. After the toxin is absorbed, the whole body tremors, tachycardia, pulse speed, and then fever; hemoglobinuria caused by massive hemolysis. In severe cases, blood pressure drops, arrhythmia, dyspnea, inability to stand, and finally fall to the ground, dying of circulatory failure and cardiac paralysis.

Symptoms of ⑸ mixed poison: the venom of cobra and king cobra is mostly mixed poison. After the animal is bitten, the local symptoms such as redness, swelling, heat, pain, infection or necrosis are obvious. After the toxin is absorbed, the symptoms caused by neurotoxin and circulatory toxin co-exist, and the systemic symptoms are serious and complex. The direct cause of death is usually asphyxia caused by respiratory center and respiratory muscle paralysis, or shock caused by vasomotor center paralysis and cardiac weakness.

two。 Pathological changes

Autopsy showed that the bite site was swollen, and the tooth marks of snakebite could only be found in the swollen center, serous infiltration under the skin, and the nearby muscle was boiled meat. Such as the death of blood circulation toxin, more common skin, mucous membrane and visceral bleeding. Myocardial hemorrhage and necrosis.