Idiopathic epilepsy in dogs is associated with dysbiotic faecal microbiota

Abstract

Background: The gut microbiota plays a crucial role in modulating various physiological and pathological processes through its metabolites, including short-chain fatty acids (SCFA), which impact immune system development, gastrointestinal health, and brain functions via the gut-brain axis. Dysbiosis, an imbalance in gut microbiota composition, has been linked to neuroinflammatory and neurodegenerative conditions, including epilepsy. In dogs, idiopathic epilepsy has been hypothesized to be influenced by gut microbiota composition, although studies on this association are limited and show inconsistent results. Here, we compared the faecal microbiota of idiopathic epileptic drug-naïve dogs and healthy controls. To this aim, we recruited 19 idiopathic epileptic dogs and 17 healthy controls which met stringent inclusion criteria and characterized their faecal microbiome by 16 S rRNA sequencing.

Results: No significant differences were observed between the two groups regarding age, breed, body condition score, diet, or reproductive status, though males were significantly overrepresented in the idiopathic epileptic group. Epileptic dogs showed a marked reduction in bacterial richness and a trend towards lower evenness (α-diversity) compared to healthy controls, while no differences in community composition (β-diversity) were observed between the two groups. Moreover, a decrease in SCFA-producing bacteria, namely Faecalibacterium, Prevotella, and Blautia, was observed alongside an increase in Escherichia coli, Clostridium perfringens, and Bacteroides in epileptic dogs.

Conclusions: Idiopathic epileptic dogs exhibit dysbiosis, with reduced bacterial diversity, loss of beneficial genera, and overgrowth of opportunistic pathogens. These alterations in microbiota diversity and composition may contribute to epilepsy via the gut-brain axis, highlighting the need for further research to explore dietary or probiotic interventions targeting gut microbiota modulation as adjunctive therapies for managing epilepsy in dogs.

Keywords: 16S rRNA; Canine idiopathic epilepsy; Dysbiosis; Epileptogenesis; Gut microbiome; SCFA.

Fig. 1

Comparison of sex (A), age (B) and body conditions score (C) between healthy and epileptic dog

Fig. 2

Faecal microbiota comparison of healthy (n = 17) and epileptic (n = 19) dogs. A) Relative microbial abundance (genus level). Only taxa with a relative abundance ≥ 2% are displayed. B) Box-plot of α-diversity calculated with Chao1 and Shannon diversity indexes. Index comparison was performed using the Wilcoxon Rank Sum test. C) Two-dimensional principal coordinates analysis (PCoA) plot based on the Bray-Curtis dissimilarity matrix. Differences in β-diversity were estimated by permutational multivariate analysis of variance (PERMANOVA) after testing for sample dispersion. D) Differentially abundant amplicon sequence variants (ASVs) between healthy and epileptic dogs identified by DESeq2. ASVs with a log₂ fold change > 2 or < 2 and adjusted p-values (q-values) > 0.05 were considered significantly associated with the health status, while only those with a log2 fold change > 3 or < 3 are shown in the volcano plot