1A)  From my view as microbiome expert, the biggest gap is that companion animal microbiome science is still far behind human research in depth, scale and standardization. For many probiotic and microbiome‑modulating ingredients, we extrapolate from human or livestock data, while species‑specific data on dogs and cats—especially well‑controlled, randomized trials—are still limited.

Even in humans this still is challenging, but we also lack robust reference microbiomes for different life stages, breeds, diets and geographies, which makes it harder to define “healthy” vs “dysbiotic” microbiomes in pets. Finally, dose–response relationships, long‑term safety, and durability of microbiome changes after supplementation are much less characterized in pets than in humans.

1B) Species specific research is critical when we talk about microbiome active ingredients. Dogs and cats have distinct gut physiology, diet, microbiota composition and immune responses compared to humans, so the same probiotic strain or prebiotic fiber can behave differently. 

Human data can be a useful starting point—for safety, basic mode of action, and initial strain selection—but it is not sufficient for efficacy claims in pets. I would always recommend at least one well designed study in the target species, ideally including microbiome profiling plus relevant clinical or functional endpoints (e.g. stool consistency, skin health, behavior, immune markers). It is also very well possible to perform ex vivo fecal fermentation experiments to investigate the effects of ingredients on composition and metabolism of pet microbiomes. 

1D) These quality parameters are all important:

• Standardization: For probiotics, this means well‑characterized strains (genomically identified), consistent CFU counts over shelf life, and clear specification of strain level, not just species. For prebiotics or postbiotics, it means defined composition and batch‑to‑batch consistency.
• Bioavailability and functionality in the target species: For microbiome modulating ingredients, it’s not about absorption but about “biofunctionality”: does the ingredient reach the relevant gut region, survive processing and storage in pet food formats, and actually shift the microbiome or metabolites in dogs/cats as intended?
• Purity and safety: Low levels of contaminants, absence of unwanted antibiotic resistance genes in probiotic strains, and safety demonstrated in the target species. 

1F) Given cost and ethical constraints, we should be realistic but rigorous:

• Study design: At least one controlled study in the target species, with appropriate controls (placebo or reference product), sufficient sample size, and pre‑defined primary endpoints.
• Endpoints: For microbiome‑focused products, a combination of:

- microbiome composition and/or functional readouts (e.g. metabolites such as Short Chain Fatty - - Acids (SCFAs), specific microbial species)
- clinically meaningful outcomes (stool consistency, frequency, skin scores, behavior scales, etc.).

• Population: Ideally, studies in the intended user group (e.g. senior dogs, animals with sensitive digestion, overweight pets), not only in healthy young animals.

We don’t need pharmaceutical‑level evidence for all supplements, but we do need more than in vitro data or human extrapolation if we want credible, specific claims.

1H) Microbiome‑oriented trials in pets face several specific challenges:

• Heterogeneity of environment and diet: Pets live in very different households, with variable diets, treats and lifestyles—all of which influence the microbiome. This can be addressed by run‑in periods, partial diet standardization, detailed dietary records, and stratification in the analysis. Trials can also be performed in controlled clinical units, which can be relevant for certain studies, but this setting lacks the influence of large environmental variability that is highly relevant in daily practice.
• Sample size and compliance: Recruiting enough animals and ensuring that owners follow protocols (dosing, sample collection, visit schedules) can be difficult. Simple protocols, owner education, collaboration with dedicated veterinarians, and user‑friendly sampling kits help.
• Microbiome technical variability: Differences in sampling, storage, DNA extraction and sequencing pipelines can obscure real effects. Using standardized, validated microbiome workflows and pre‑defined analysis plans is of high importance.
• Ethical and regulatory constraints: Especially when working with clinical populations, trial designs must minimize burden on animals and owners, which can limit invasive measurements.

1L) Yes, there is a clear trend toward “healthy ageing” formulations for pets, and microbiome modulating ingredients are increasingly part of that story. We see growing interest in modulating ingredients are increasingly part of that story. We see growing interest in:

• Probiotic strains selected for gut barrier support, immune modulation, and potential effects on low grade inflammation.
• Prebiotics and fibers tailored to promote beneficial taxa and SCFA production, which may support metabolic and gut health in senior animals.
• Postbiotics and fermented ingredients that deliver defined microbial metabolites without live cells, which can be attractive from a stability and safety perspective.