How do we have any idea what is going on in a horse's brain? Of course we can not ask a horse how they feel, or if they remember the task we asked of them the day before, but we can use technical tools to measure and use our observation through:
Science - is a systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions.
Natural science - a branch of science concerned with the description, prediction, and understanding of natural phenomena, based on empirical evidence from observation and experimentation. Mechanisms such as peer review and repeatability of findings are used to try to ensure the validity of scientific advances.
Biological Markers - through chemicals tested in blood ,feces, and urine.
Biology is concerned with the characteristics, classification and behaviors of organisms, as well as how species were formed and their interactions with each other and the environment.
Understanding the similarities and differences of the mammalian brain offers clearer insight to the form and function of the brain and central nervous system of each species.