In the past strychnine has been used as an antiseptic, stomach tonic, circulatory stimulant, central nervous system stimulant, and as a medication for the relief of constipation. Strychnine is still in limited use today as a bird, mammal, and insect control agent. It is primarily used in a cracked corn bait to eliminate unwanted bird populations, but occasionally other wildlife species are inadvertently poisoned.
All animals are susceptible to strychnine poisoning, but birds are more frequently affected.
Following ingestion, strychnine is rapidly absorbed through all mucous membranes especially the stomach and small intestines and is rapidly eliminated by the kidney and liver. The clinical signs of strychnine poisoning relate to its effects on the central nervous system. The first clinical signs include uneasiness, restlessness, anxiety, muscle twitching and stiffness of the neck. The animal is in severe pain and the pupils are dilated. These signs can resemble tetanus, with an increase in spinal reflexes leading to tonic convulsions characterized by sudden contractions of all striated muscles followed by complete relaxation.