The effects on animals occur very rapidly and strongly, all resulting in death. Exposure to a high concentration of MFA vapor does not show any symptoms in animals until 30–60 minutes. Then violent reactions and death took place in a few hours, according to studies. From intravenous injection mice, rats, and guinea pigs show symptoms after 15 min to 2 hours. The animals become quiet and limp. Rabbits show a similar latent time period and muscle weakness. Dogs show symptoms of hyperactivity. They are more sensitive because of higher rates of metabolism and, eventually, they also fail to respirate. Fish are more resistant because of slow metabolism and therefore it is not expected that the substance will build up in fish. Also, Australian herbivores (e.g. possum and seed-eating birds) that live in a habitat consisting of plants with traces of fluoroacetate, have some tolerance. This can happen by detoxifying fluoroacetate or more resistivity of aconitase to fluorocitrate in the presence of GSH. Some insects can store the toxin in vacuoles and use it later. The highly hazardous MFA cannot be used for poisoning animals without risking human life.