Abstract
The gastrointestinal tract is a large number of microorganisms that play a key role in the physiology and pathology of animals. The whole of these live microorganisms is known as gut microbiota and it is one of the biggest ecosystems on Earth. Recent studies on dogs and cats have become the microbiota involved in a wide range of life processes, including energy needs, metabolism, immunological activity and neuro-behavioral development, and to come even modifications of a few bacterial species can induce the onset of diseases. Recently molecular approaches have worked with a wide range of data on the correlation between the physiological functions and the phylogenies of healthy and sick animals (Suchodolski et al., 2008a, Swanson et al., 2011). This review focuses on the role of the microbiota on the health of pets and will discuss changes that occur in the disease.