The aquatic plant Wolffia globosa and the probiotic Limosilactobacillus reuteri KUB-AC5 have been proposed as candidate synbiotic components targeting gut microbiota modulation. In this study, we investigated the effects of W. globosa supplementation, alone or in combination with L. reuteri KUB-AC5, on the gut microbiota and health status in healthy adult dogs. For a 28-day feeding trial, 24 healthy dogs were randomly assigned to three dietary treatment groups: control, prebiotic (PRE; 3.5% W. globosa powder), and synbiotic (SYN, 3.5% W. globosa powder combined with L. reuteri KUB-AC5 at 1 × 10⁸ CFU/day). No significant differences were observed in body weight, body condition score, fecal consistency, feed intake, or blood parameters among groups (p > 0.05). Although overall gut microbial diversity remained unchanged, linear discriminant analysis effect size analysis revealed the selective enrichment of specific bacterial taxa. The PRE group exhibited higher relative abundances of Parabacteroides merdae, Romboutsia lituseburensis, Subdoligranulum variabile, and Phocaeicola sartorii, whereas the SYN group showed increased levels of Escherichia coli and Terrisporobacter glycolicus and reduced levels of Anaerobiospirillum succiniciproducens and Campylobacter upsaliensis (p < 0.05). In conclusion, W. globosa, alone or combined with L. reuteri KUB-AC5, was safely used to modulate gut bacterial composition as a potential functional ingredient.

In vitro fecal inoculation coupled with gas chromatography–mass spectrometry (GC-MS) has been used for evaluating fecal deodorants. However, high cost and complex data interpretation limit its routine application. An electronic nose (eNose) offers a rapid, cost-effective alternative. This study aimed to evaluate the eNose as a screening tool for fecal odor compared with solid-phase microextraction gas chromatography–mass spectrometry (SPME GC-MS) and to examine the in vitro effects of fecal deodorant supplements on fecal odor profiles. Feces from ten healthy cats were serially diluted (1:1 to 1:8) and analyzed using both instruments. Four dietary supplements—Yucca schidigera extract (YSE), Quillaja saponaria extract (QSE), fructooligosaccharides (FOS), and oat beta-glucans (OBG)—were tested at concentrations of 0.0, 0.2, 0.4, and 0.8 g/100 mL. The eNose showed comparable performance to GC-MS in discriminating among sample dilutions. In vitro fermentation showed that FOS and OBG significantly increased volatile fatty acid (VFA)-related sensor responses while signals linked to ammonia and sulfur compounds were reduced. QSE had minimal effect, whereas YSE produced moderate changes. The total sensor response intensities did not differ between treatments. These findings indicate that prebiotic supplements exert stronger effects than saponin-based supplements and highlight the potential of eNoses with in vitro fermentation for rapid screening of fecal deodorants.