Variation of the Dog-Microbiome in Relation to Environmental Factors

To advance the understanding of these factors, this thesis synthesizes findings from seven key studies, each examining various aspects of canine gut microbiome health and dietary interventions. The first Chapter investigates the potential of probiotics and nutraceuticals to enhance gut health in both dogs and cats, highlighting how targeted supplementation can restore microbial balance and promote resilience against gut-related disorders (Publication 5, Pets Journal, July 2024). Building on this, research into microbiota development in puppies from birth to weaning provides valuable insights into how early-life factors influence microbial diversity and stability, underscoring the importance of establishing a robust microbiome foundation during critical developmental periods (Chapter 3, Publication 1, Animals Journal, February 2023). Subsequent studies examine the effects of various supplements on the gut microbiome in dogs with specific health needs. The study on overweight dogs shows how supplementation with Silybum marianum extract, synbiotics, omega-3 fatty acids, vitamins, and minerals can positively impact both biochemical markers and microbiome composition, suggesting a holistic approach to weight management through microbiome modulation (Chapter 4, Publication 2, Animals Journal, February 2024). Another study explores the role of a mix of nutraceuticals on microbiota composition, shedding light on how such interventions might support immune function and gut health in general (Chapter 5, Publication 3, Animals Journal, April 2024). Chapter 6 examines the effects of grape proanthocyanidins (GPAC) on gut microbiota and endocrine responses in dogs. GPAC supplementation influenced specific microbial taxa, including increases in Dorea and Clostridium, and improved serotonin-to-cortisol ratios at higher doses. These findings highlight GPAC's potential role in modulating gut and endocrine health (Publication 6, Animal Feed Science and Technology Journal, September 2024). Furthermore, in Chapters 7-8, long-term studies on dietary interventions with hydrolyzed feather meal provide evidence of how partial substitution of dietary protein can minimally affect gut microbiota composition dogs, indicating the possibility of the use of by product in the pet industry for food production in a view of cicular economy (Chapter 7, Publication 4, Research in Veterinary Science Journal, June 2024). the substitution of poultry meal with hydrolyzed feather meal (HFM) in dog diets is assessed. While health parameters remained unaffected, HFM influenced gut microbiota composition, enriching specific taxa like Fusobacterium and Faecalibacterium, with distinct microbiome differences observed between sexes (Chapter 8, Publication 7, Microorganisms Journal, January 2025). Lastly, Chapter 9 evaluated the impact of dry, moist, and home-made diets on short-chain fatty acid (SCFA) profiles in dogs. The moist diet produced the highest SCFA levels, while the home-made diet favored butyric, lactic, and propionic acid proportions. These findings underscore the role of diet in shaping canine gut microbiota and SCFA production (Chapter 9, Publication 8, under Submission in Research in Veterinary Science Journal, January 2025). Collectively, these studies reveal a nuanced picture of the gut microbiome as an adaptable and responsive system shaped by a multitude of interacting factors. Environmental exposures and dietary habits further influence microbial diversity and function. These findings underscore the potential of diet to serve as a powerful, customizable tool for supporting gut health. In particular, the use of supplements such as probiotics, prebiotics, and nutraceuticals offer a promising avenue for targeted microbiome interventions.