Longitudinal Metagenomic Study Shows No Significant Gut Microbiome Disruption in Dogs Undergoing Leishmaniosis Treatment

Leishmaniosis remains a major zoonotic concern in Europe and globally, and while therapeutic strategies are well-established, the impact of treatment on the gut microbiota has been largely unknown. Understanding whether commonly used antileishmanial therapies—namely meglumine antimoniate and allopurinol—affect the gut microbiome is essential, as microbiome impairment may have consequences for host health, immune function, and treatment recovery.

This multicenter study was conducted in three countries (Spain, Portugal, and Italy) and involved a cohort of privately owned dogs with clinically diagnosed leishmaniosis. The study was coordinated by Nano1Health, with support from Nestlé Purina PetCare Europe, and in collaboration with three leading veterinary institutions: the Hospital Clínic Veterinari from Universitat Autònoma de Barcelona (Spain), the Centre for Interdisciplinary Research in Animal Health (CIISA-FMV ULisboa, Portugal), and the University of Naples Federico II (Italy).

Study Design and Methods

A total of ten dogs were monitored at three timepoints: before treatment (baseline, BL), after one month of combination therapy (meglumine antimoniate and allopurinol, M1), and after six months of allopurinol monotherapy (M6). Fecal samples were collected at each timepoint, and DNA was extracted and sequenced via shotgun metagenomics on an Illumina HiSeq platform. Sequencing reads were processed using a combination of Metaphlan3, Bowtie2, and the Integrated Gene Catalog, with taxonomic and functional analysis performed using phyloseq, vegan, LEfSe, and MaAsLin2 tools in R.

Key Findings

1. Across all timepoints, the gut microbiome composition remained stable, with no significant alterations in taxonomic or functional diversity (alpha or beta).

2. The most represented genera across the cohort included Prevotella, Collinsella, Blautia, and Bacteroides, consistent with prior studies of healthy canine microbiota.

3. Notably, individual dog variability explained more than 50% of observed microbiome diversity, reinforcing the importance of host-specific factors.

4. Although slight, non-significant enrichment trends were observed for taxa such as Bifidobacterium pseudocatenulatum and Slackia piriformis following treatment, these did not represent meaningful shifts in community structure.

Implications

These results indicate that the widely recommended treatment protocol does not induce detectable microbiome impairment in Leishmania-infected dogs. This is an important insight for veterinary clinicians, as it suggests the intestinal microbiome remains resilient throughout the course of standard antileishmanial therapy. Preserving microbial homeostasis may be crucial for immune modulation, gut integrity, and overall recovery, especially in chronic infectious conditions.

About the Project

This work aligns with Nano1Health's commitment to bridging genomics research and practical diagnostics in the One Health context. It was funded by Nestlé Purina PetCare Europe, although all research design, execution, and interpretation were carried out independently by Nano1Health scientists and academic partners.

Full Article Access

The article is open access and available at: https://rdcu.be/exAZ7

For further information about this study or our research initiatives in microbiome, infectious disease and genomics, please contact us at info@nano1health.com