Past, Present, and Future of Gastrointestinal Microbiota Research in Cats

Abstract

The relationship between microbial community and host has profound effects on the health of animals. A balanced gastrointestinal (GI) microbial population provides nutritional and metabolic benefits to its host, regulates the immune system and various signaling molecules, protects the intestine from pathogen invasion, and promotes a healthy intestinal structure and an optimal intestinal function. With the fast development of next-generation sequencing, molecular techniques have become standard tools for microbiota research, having been used to demonstrate the complex intestinal ecosystem. Similarly to other mammals, the vast majority of GI microbiota in cats (over 99%) is composed of the predominant bacterial phyla Firmicutes, Bacteroidetes, Actinobacteria, and Proteobacteria. Many nutritional and clinical studies have shown that cats' microbiota can be affected by several different factors including body condition, age, diet, and inflammatory diseases. All these factors have different size effects, and some of these may be very minor, and it is currently unknown how important these are. Further research is needed to determine the functional variations in the microbiome in disease states and in response to environmental and/or dietary modulations. Additionally, further studies are also needed to explain the intricate relationship between GI microbiota and the genetics and immunity of its host. This review summarizes past and present knowledge of the feline GI microbiota and looks into the future possibilities and challenges of the field.

Keywords: feline; gastrointestinal tract; microbiome; molecular techniques; nutrition and diseases.

FIGURE 1

The dominant bacterial groups in the feline gastrointestinal tract. Summarized from Osbaldiston and Stowe (1971), Johnston et al. (1993, , , Inness et al. (2007), Desai et al. (2008), Janeczko et al. (2008), Ritchie et al. (2008), Abecia et al. (2010), Barry et al. (2010, , Garcia-Mazcorro et al. (2011), Jia et al. (2011a, , Sparkes et al. (1998b), and Tun et al. (2012). All bacteria were identified from fecal samples or intestinal biopsies by the molecular method.

FIGURE 2

What is the future of the gastrointestinal microbiota in cats?