Cognition is a set of activities and processes whereby an animal acquires information and develops knowledge. The most common cognitive processes are: memory, categorization, attention, reasoning and language. This present research was aimed to study the cognitive ability of livestock based on results of cognitive tests described in the literature, as well to expose the various types of tests applied to make such an assessment, in the periods from 1969 until nowadays. Through this bibliographic study, it was discussed issues related to cognition, sentience and animal consciousness, through preference tests, learning, recognition and memorization applied to domestic animals. In general they show a cognitive ability to evaluate the environment for themselves, based on their preferences and motivations. Cognitive tests have shown the high ability of some species to memorize their handlers’ faces, and recognize who is aversively dealing with. Furthermore, it was possible to prove that some producing species are sentient and their choices able to imply physical sensations that can affect your mental state. Thus, it is important to point out measures to help improve the well-being of the animals.