The distracted dog: can gut health affect focus and behaviour?

ADHD, dogs and the gut microbiome

We know that ADHD is a significant mental health issue in humans. Several human studies have suggested a bidirectional link between gut microbial profiles and ADHD, mainly through the gut-brain axis. Perhaps less commonly known is the fact that dogs can suffer from similar neurodevelopmental disorders[1] [2], including ADHD[3].

The gut link

A clear body of work existed prior to 2025 on similarities between the gut microbiota composition of dogs and humans and response to diet[4][5]. As far back as 201, studies into ADHD-like traits in dogs were creating behavioural tests and owner/trainer questionnaires to assess inattention, hyperactivity and impulsivity in dogs[6]*.

But as far as I can see, a very interesting study published recently[7] is the first to investigate how variation in the domestic dog’s gut microbiome can be linked to ADHD-like traits, drawing parallels with the human ADHD/microbiome relationship. For example, the relationship between inattention and the relative abundance of certain bacteria.

Diversity

Alpha-diversity is the ecological diversity – species richness and evenness – within a single sample (as opposed to beta-diversity, which is the difference between samples). The association of lower alpha-diversity with higher functional impairment scores indicates poorer microbial health in dogs with more pronounced behavioural challenges.

A varied microbiome supports a wider range of metabolic activities, such as the production of short-chain fatty acids and conversion of amino acids into bioactive compounds that the body can use. It follows that a system with fewer species will automatically have a narrower range of metabolic tools and consequently becomes less resilient, less adaptable and potentially less stable. Or can be associated with functional impairment, as we see here.

When specific populations are low, the dog isn’t just missing certain bacteria; it is missing the chemical messengers those bacteria produce to support focus and regulation. (See also quorum sensing.)

We already know that the gut microbiome helps to produce and modulate compounds that influence the central nervous system. Metabolites derived from tryptophan feed into serotonin pathways. Remember serotonin, the happy hormone? A 2023 study[8] had already found a strong relationship between low levels of serotonin and dopamine and dogs with ADHD-like disorders.

Balance

This perspective is supported by evidence from other behavioural studies. Research into adrenocortical activity (stress hormone response) in dogs with behavioural disorders[9] shows that dogs with different behavioural profiles also have distinct microbiome compositions, and that a dysbiotic gut in aggressive dogs exacerbates behaviour. Perhaps more interestingly for us as owners, it went on to suggest the potential of mitigating behavioural disorders by restoring balance and improving overall gut health.

It is important to note that while these studies point to a consistent theme, they also show that the relationship is complex. It isn’t so much a simple mantra of “more diversity is better”, more that composition and balance are just as important. Hence the goal of a structured feeding pattern is to build functional stability and balance.

True stability doesn’t come from constantly introducing random new species. It comes from having a solid core of resident microbes that can all perform the same vital jobs (like producing short-chain fatty acids or converting tryptophan), even when conditions change. This is called functional redundancy. Keeping the resident, beneficial microbial families securely anchored and working efficiently also allows them to outcompete and naturally suppress the opportunistic strains that thrive on undigested waste and inflammation.

Dietary pattern plays directly into this; the microbiome is responsive to what it is fed. A rotation of clean, highly bioavailable ingredients and targeted fibre structures helps to ensure the system is efficient and resilient. One that is in the best condition to process nutrients, maintain a calm gut environment and smoothly adapt to all those internal and external demands.

None of this suggests that behaviour can be reduced to diet or microbiome alone. There are other significant factors, including stress, age, environment and genetics[10]. Training also plays a role. But what these findings have done is to add a biological dimension that has often been overlooked in practical feeding discussions. They show that the gut microbiome is an active participant in physiological and behavioural outcomes.

Food, in this sense, becomes part of a broader system – one that begins in the gut, but extends into how the dog functions as a whole.

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*Waltham catalogue

Note: A groundbreaking study[11] published in 2026 has produced a truly comprehensive catalogue of the canine microbiome. This catalogue increases mapping rates from 25% of microbes to around 95%, showing that the canine microbiome is far more distinct than first thought. Its findings highlight even further the importance of the canine microbiome to nutrition: it identified previously unknown species that provide metabolic function to the canine host; found a strong host reliance on the commensal bacteria of the gut to process carbohydrates; and even discovered a range of species that can produce butyrate, propionate and vitamins. This more complete picture will almost inevitably refine the interpretation of at least some earlier studies that were based on far less information.

Something to keep an eye on….

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References:

[1] Ambrosini YM, Borcherding D, Kanthasamy A, Kim HJ, Willette AA, Jergens A, et al. The gut-brain axis in neurodegenerative diseases and relevance of the canine model: a review. Front Aging Neurosci. 2019;11:130.https://doi.org/10.3389/fnagi.2019.00130.
[2] Topál J, Román V, Turcsán B. The dog (Canis familiaris) as a translational model of autism: it is high time we move from promise to reality. WIREs Cogn Sci. 2019;10:e1495. https://doi.org/10.1002/wcs.1495.
[3] Bunford N, Csibra B, Gácsi M. Individual differences in response to ambiguous stimuli in a modified Go/no-go paradigm are associated with personality in family dogs. Sci Rep. 2019;9:11067. https://doi.org/10.1038/s41598-019-47510-z.
[4] Csibra B, Reicher V, Csepregi M, Kristóf K, Gácsi M. Towards an Objective Measurement Tool for ADHD-like Traits in Family Dogs: A Comprehensive Test Battery. Animals (Basel). 2024 Jun 21;14(13):1841. doi: 10.3390/ani14131841. PMID: 38997953; PMCID: PMC11240718.
[5] Coelho LP, Kultima JR, Costea PI, Fournier C, Pan Y, Czarnecki-Maulden G, et al. Similarity of the dog and human gut microbiomes in gene content and response to diet. Microbiome. 2018;6:72. https://doi.org/10.1186/s40168-018-0450-3.
[6] Ito Y, Nagasawa M, Koyama K, Ito K, Kikusui T. Comparative analysis based on shared amplicon sequence variants reveals that cohabitation influences gut microbiota sharing between humans and dogs. Front Vet Sci. 2024;11:1417461. https://doi.org/10.3389/fvets.2024.1417461.
[7] Salamon, A., Szabó, A., Felföldi, T. et al. Human-like associations between gut microbiome composition and inattention, hyperactivity, and impulsivity in dogs. BMC Biol 23, 352 (2025). https://doi.org/10.1186/s12915-025-02410-9
[8] González-Martínez, Á., Muñiz de Miguel, S., Graña, N., Costas, X., & Diéguez, F. J. (2023). Serotonin and Dopamine Blood Levels in ADHD-Like Dogs. Animals, 13(6), 1037. https://doi.org/10.3390/ani13061037
[9] Mondo E, Barone M, Soverini M, D’Amico F, Cocchi M, Petrulli C, Mattioli M, Marliani G, Candela M, Accorsi PA. Gut microbiome structure and adrenocortical activity in dogs with aggressive and phobic behavioral disorders. Heliyon. 2020 Jan 29;6(1):e03311. doi: 10.1016/j.heliyon.2020.e03311. PMID: 32021942; PMCID: PMC6994854.
[10] Williams CE, Hammer TJ, Williams CL. Diversity alone does not reliably indicate the healthiness of an animal microbiome. ISME J. 2024 Jan 8;18(1):wrae133. doi: 10.1093/ismejo/wrae133. PMID: 39018234; PMCID: PMC11334719.
[11] Castillo-Fernandez J, Gilroy R, Jones RB, Honaker RW, Whittle MJ, Watson P, Amos GCA. Waltham catalogue for the canine gut microbiome: a complete taxonomic and functional catalogue of the canine gut microbiome through novel metagenomic based genome discovery. Microbiome. 2026 Jan 17;14(1):25. doi: 10.1186/s40168-025-02265-w. PMID: 41547860; PMCID: PMC12811905.

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Important Considerations:

• Always consult your veterinarian before making any significant dietary changes, particularly where there are pre-existing health conditions or dietary restrictions.
• If you are feeding commercial food, check the label for ingredients before giving more. Excessive intake of any foods can have adverse effects.
• Ensure (where possible) that you use high-quality, organic products specifically formulated for pets (or better still, human grade ingredients) to avoid any potential adverse effects.
• Introduce new foods gradually to avoid adverse effects such as gastrointestinal upset or diarrhoea.
• I provide nutritional information purely as a helpful guide. Nutritional information on ingredients is obtained from the US Department of Agriculture’s FoodData Central site (https://fdc.nal.usda.gov/index.html) and any nutritional information provided in recipes is based on an online calculator: calories and other information will vary based on brands, ingredients and other factors.
• Check nutrient levels and recommendations for your dog’s weight, age and activity. For example this nutritional guideline produced by FEDIAF.
• I am not a professional canine nutritionist but supporting research is cited.
• The recipes shared were created by me and tested in my kitchen – and tasted and approved by our doggy friends!

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