# Differential Gene Expression Analysis of Whole Blood Transcriptome Between Young and Old Border Collie Dogs

## TL;DR

This study compares gene activity in blood samples from young and old border collie dogs to find signs of healthy aging.

## Contribution

The study identifies a limited set of age-related gene expression changes in whole blood of healthy aging dogs.

## Key findings

- Only 61 genes showed significant age-related expression differences in blood samples from young and old dogs.
- Multidimensional scaling analysis could not clearly separate young and old dogs based on gene expression.
- The results suggest a need for standardized environmental controls and hemoglobin depletion in future blood transcriptomic studies.

## Abstract

Aging is a major risk factor for various diseases. Understanding the mechanisms of healthy aging can aid in developing treatments for elderly individuals and promoting healthier lifestyles. Studying aging in humans is challenging due to their long lifespans, making companion dogs valuable alternative models because of their shared environment with humans and shorter lifespans. This study analyzed gene expression differences in whole blood between young adults and elderly healthy border collie dogs to identify potential biomarkers of healthy aging. Whole blood is a practical and minimally invasive sample source, reflecting systemic physiological changes and enabling longitudinal studies. The study found only a limited number of genes with significant age-related differences, which aligns with findings in dogs but contrasts with studies in other species that report broader transcriptomic changes with age. These results underscore the need for further research to clarify the blood transcriptomic basis of healthy aging in dogs and humans.

Aging is the most significant risk factor for many diseases and increased mortality, and it is influenced by both genetic and environmental factors. In this study, our primary goal was to investigate age-related gene expression changes in whole blood samples collected from dogs and identify potential biomarkers of healthy aging. We sequenced the mRNA fraction of whole blood samples from five young and five old border collie dogs and performed differential gene expression and differential transcript usage analyses. The raw sequencing data exhibited high quality. Multidimensional scaling analysis failed to differentiate age clusters. Moreover, we identified only a limited number of differentially expressed genes (n = 61) and 30 genes with differential transcript usage between the blood transcriptomes of young and old dogs. Our results align with publicly available data on dogs. However, studies on other species, such as wolves, have identified more significant age-related genes. In conclusion, while some of our findings are promising, further research is needed to standardize environmental factors affecting blood gene expression levels in dogs. Additionally, we recommend implementing pre-sequencing hemoglobin depletion to improve the analysis of whole blood in future studies.