A chemical plant produces an insecticide that makes small mammals such as otters infertile. After the factory began operation, the incidence of infertility of an otter living in a nearby river increased rapidly. Therefore, the factory must have polluted the river when producing pesticides.
 The bacteria that cause tetanus live in the digestive tract of horses. Tetanus is a highly contagious disease. Therefore, horses must be more likely to catch tetanus than most other animals contains a reasoning error that is most similar to the one above.