They are typically resistant to most problems encountered in horses, such as wounds, chronic lameness, infectious diseases, and digestive disorders. However, it is myth that mules will not founder or colic, even though they are less susceptible than horses. They can have heavy lungworm infestations without showing any symptoms and can be silent carriers of the parasite. Mules pastured with horses should be tested and treated for lungworm regularly. Horses never forget but they usually forgive.
Mules never forget and never forgive.
Mules are always thinking, and they have a strong sense of self-preservation. They resent being hurt and when mistreated they become very evasive and uncooperative. While horses usually run from scary stimuli, mules are likely to attack. Mules kick with greater accuracy than horses, and they can kick in any direction and strike anything within their reach. However, a mule is neither vicious or stubborn but will respond as treated.