Effect of Lactobacillus supplementation on seizure control, gut microbiota, and blood neurotransmitters in dogs with idiopathic epilepsy

Idiopathic epilepsy is one of the most common neurological diseases in dogs; however, epileptogenesis and the mechanisms underlying drug resistance remain poorly understood. This study aimed to evaluate the effects of three months of supplementation with canine-derived Lactobacillaceae strains on seizure frequency in dogs with drug-sensitive epilepsy (DSE) and drug-refractory epilepsy (DRE). Additionally, gut microbiota profiles and plasma levels of GABA, L-glutamate, and serotonin were analysed and compared to those of healthy control dogs. The probiotic supplementation was associated with a reduction in both the number of seizures and seizure days in epileptic dogs. An increase in the relative abundance of gut Lactobacillus and plasma GABA levels did not accompany clinical improvement. However, it was associated with a significant decrease in the GABA/L-Glutamate ratio in dogs with DSE but not in those with DRE. At baseline, heterogeneity of the fecal microbial community (β-diversity) was higher in epileptic compared to controls. Following probiotic supplementation, the differences in β-diversity between control and DSE dogs were no longer observed. The probiotic had no notable effect on the control group but was associated with a significant reduction in β-diversity in dogs with DRE. While the relative abundance of Lactobacillus remained unchanged after probiotic administration, some changes in gut microbiota were observed in epileptic dogs. Numerous associations were identified between seizure frequency and specific bacterial taxa with potential protective effects (e.g.,Prevotella_9, Ligilactobacillus) or risk effects (e.g.,Parasutterella, Helicobacter). These findings suggest that long-term use of Lactobacillus may serve as a promising adjuvant strategy for seizure control.