The drug that kills dogs when they smell it is called isoniazid. After isoniazid enters the dog's body, it reaches the peak of plasma value in about 30 minutes, which can cause the dog's myocardial necrosis and cause severe metabolic acidosis. Under normal circumstances, the cure rate is only 10%. The toxicity of isoniazid is not limited to dogs, but can also produce strong neurotoxicity to cats, rats, chickens, ducks and other animals.

There is also potassium cyanide, which is extremely toxic to dogs. Once sniffed by dogs, this drug can cause severe central nervous system depression in them. Initially, the dog will experience muscle spasms, which may eventually lead to respiratory failure, cardiac arrest, and death. Under normal conditions, pure potassium cyanide is extremely stable and will not decompose.