# Variations in the Gut Microbiota of Stray and Domestic Cats

## TL;DR

Stray cats have gut bacteria adapted to harsh conditions, while domestic cats have more diverse and health-supporting gut microbes.

## Contribution

This study reveals how environmental differences shape the gut microbiota of stray versus domestic cats.

## Key findings

- Domestic cats have higher gut microbiota diversity and more complex microbial networks.
- Stray cats have more stress-tolerant and potentially pathogenic bacteria like Escherichia-Shigella.
- Gut microbes in domestic cats are linked to DNA repair and health maintenance, while those in strays are linked to stress response.

## Abstract

Cats living outdoors as strays face very different conditions from those kept as pets—including unpredictable food sources, exposure to pathogens, and lack of veterinary care. This study asked whether these differences affect the bacteria living in the cat’s gut. We compared the gut microbiota of stray and domestic cats using genetic sequencing of fecal samples. We found that domestic cats have more diverse and stable gut bacterial communities. Stray cats, on the other hand, carry more bacteria that can tolerate stress and survive with or without oxygen. Some bacteria linked to potential infections, such as Escherichia-Shigella, were also more common in stray cats. The gut bacteria of stray cats appear to be geared toward surviving in harsh environments, while those in domestic cats seem more involved in maintaining general health. These results help us understand how the environment shapes gut health in cats and may guide strategies to reduce disease risks to cats and humans under the “One Health” framework.

Urban stray cats are in close contact with humans and are important potential vectors for zoonotic diseases. However, comparative studies in the gut microbiota of cats living in different environments remain limited. Here, we conducted a comparative analysis of the gut microbiota between stray and domestic cats using 16S rRNA gene sequencing of fecal samples from 14 stray and 11 domestic cats in Hefei, China. Domestic cats harbored significantly higher alpha diversity (Sobs index, Padj. = 0.039; Shannon index, Padj. = 0.024) and more complex microbial co-occurrence networks than stray cats. Beta diversity analysis confirmed distinct community structures between the groups. Linear discriminant analysis identified 12 taxa enriched in stray cats, including Escherichia-Shigella and other potential opportunistic pathogens. Functional prediction indicated that the gut microbiota of domestic cats was enriched in genes related to DNA repair and cellular structure maintenance, whereas that of stray cats showed higher abundance of functions associated with secondary metabolism, defense mechanisms, and stress response. Phenotypic prediction further revealed increased proportions of stress-tolerant and facultatively anaerobic bacteria in stray cats. These findings demonstrate that lifestyle and environmental exposure shape the feline gut microbiota, with stray cats exhibiting a less diverse, more stress-adapted, and potentially pathogen-enriched microbial profile. This study provides insights into the ecological adaptation of gut microbiota and highlights implications for zoonotic risk and One-Health-oriented management of urban cat populations.