Yeast products may serve as functional ingredients due to their benefits on host health, but vary greatly in source, composition, and functionality, justifying research in host species of interest. In this study, a Saccharomyces cerevisiae fermentation product (SCFP) was investigated as a dietary supplement for adult dogs. Adult female beagles (n = 12; mean age = 3.3 ± 0.8 yr; mean BW = 10.3 ± 0.68 kg) were fed the same diet, but supplemented with 3 levels of SCFP (125, 250 and 500 mg/d) or a placebo (sucrose) via gelatin capsules in a replicated 4 x 4 Latin square design. Fecal samples for nutrient digestibility, fecal characteristics and microbial populations as well as blood samples for immune indices were collected after a 21-d adaptation phase in each period. A separate palatability test was conducted to examine palatability of a SCFP-containing diet (0.2% of diet). All data, except for palatability data, were analyzed by Mixed Models procedure of SAS (version 9.4). A paired t-test was conducted to analyze data from the palatability test. Supplementation of SCFP did not affect total tract apparent macronutrient and energy digestibilities or fecal characteristics. Fecal phenol and total phenol + indole concentrations decreased linearly with SCFP dosage (P < 0.05). Relative abundance of Bifidobacterium was greater (P < 0.05), while Fusobacterium was lower (P < 0.05) in SCFP-supplemented dogs. Total white blood cell counts were decreased by SCFP (P < 0.05). The percentage of NK cells and antigen-presenting cells were not altered by SCFP. However, when comparing control vs. all SCFP treatments, SCFP-supplemented dogs had greater (P < 0.05) MHC-II presenting B cell and monocyte populations than control dogs. IFN-γ secreting helper and cytotoxic T cells increased linearly with SCFP consumption (P < 0.05). Immune cells derived from SCFP-supplemented dogs produced less (P < 0.05) TNF-α than those from control dogs when cells were stimulated with agonists of toll-like receptors 2, 3, 4 and 7/8. A linear increase (P < 0.05) in serum IgE with SCFP dosage was noted. In the palatability test, a 1.9:1 consumption ratio was observed for the SCFP-containing diet vs. control diet, demonstrating a preference (P < 0.05) for SCFP. Results of this study suggest that SCFP supplementation may be beneficial to adult dogs by positively altering gut microbiota, enhancing immune capacity and reducing inflammation.

Similar to humans, the fecal microbiome of dogs may be useful in diagnosing diseases or assessing dietary interventions. The accuracy and reproducibility of microbiome data depend on sample integrity, which can be affected by storage methods. Here, we evaluated the ability of a stabilization device to preserve canine fecal samples under various storage conditions simulating shipping in hot or cold climates. Microbiota data from unstabilized samples stored at room temperature (RT) and samples placed in PERFORMAbiome·GUT collection devices (PB-200) (DNA Genotek, Inc. Ottawa, Canada) and stored at RT, 37 °C, 50 °C, or undergoing repeated freeze–thaw cycles, were compared with freshly extracted samples. Alpha- and beta diversity indices were not affected in stabilized samples, regardless of storage temperature. Unstabilized samples stored at RT, however, had higher alpha diversity. Moreover, the relative abundance of dominant bacterial phyla (Firmicutes, Fusobacteria, Bacteriodetes, and Actinobacteria) and 24 genera were altered in unstabilized samples stored at RT, while microbiota abundance was not significantly changed in stabilized samples stored at RT. Our results suggest that storage method is important in microbiota studies and that the stabilization device may be useful in maintaining microbial profile integrity, especially for samples collected off-site and/or those undergoing temperature changes during shipment or storage.

Antibiotics are known to cause loose stools, disrupt the fecal microbiota, and alter fecal bile acid (BA) profiles of dogs. Recovery may be aided by diet, but little research has been conducted. The objective of this study was to determine how a veterinary low-fat diet affected the fecal characteristics, metabolites, BA, and microbiota of dogs receiving antibiotics. Twenty-four healthy adult dogs [7.38 ± 1.95 yr; 7.67 ± 0.76 kg body weight (BW)] were used in an 8-wk completely randomized design study. During a 2-wk baseline, all dogs were fed a leading grocery brand diet (GBD). Over the next 2 wk, dogs were fed GBD and received metronidazole orally (20 mg/kg BW twice daily). At week 4, dogs were randomly allotted to one of two treatments [GBD or Blue Buffalo Natural Veterinary Diet GI Gastrointestinal Support Low-Fat (BB)] and fed for 4 wk. Fecal scores were recorded daily and fresh fecal samples were collected at weeks 2, 4, 5, 6, 7, and 8 for measurement of pH, dry matter content, and metabolite and BA concentrations. Fecal microbiota populations were analyzed using 16S rRNA gene amplicon sequencing and qPCR-based dysbiosis index (DI). All data were analyzed as repeated measures using the Mixed Models procedure of SAS 9.4, testing for effects of treatment, time, and treatment*time and significance set at P < 0.05. Metronidazole increased (P < 0.0001) fecal scores (looser stools), reduced fecal short-chain fatty acid, branched-chain fatty acid, phenol, and indole concentrations, increased primary BA concentrations, and decreased secondary BA concentrations. Metronidazole also reduced fecal bacterial alpha diversity, altered the abundance of 58 bacterial genera, and increased DI. During antibiotic recovery, changes in fecal pH, dry matter percentage, and metabolite and immunoglobulin A concentrations were altered (P < 0.05) by diet. Fecal BA concentrations recovered quickly for all dogs. Change in lithocholic acid was affected (P < 0.0001) by diet, but other BA were not. Recovery of over 25 bacterial genera was impacted by diet (P < 0.05). While many bacterial taxa returned to baseline levels after 4 wk, others did not fully recover. DI and bacterial alpha diversity measures recovered quickly for all dogs but were not impacted by diet. In conclusion, metronidazole drastically altered the fecal microbiota and metabolites of dogs. While most variables returned to baseline by week 8, diet may be used to aid in recovery.

Antibiotics are used to treat gastrointestinal diseases or infections but are known to negatively affect stool quality and gut microbiota in cats and dogs. Therefore, identifying dietary strategies that may aid in antibiotic recovery is of interest. The objective of this study was to determine how a veterinary gastrointestinal diet affected the fecal characteristics, microbiota, and metabolite and bile acid (BA) concentrations of cats recovering from metronidazole administration. Twenty-four healthy adult cats were used in an 8-wk completely randomized design study. During a 2-wk baseline, all cats consumed a leading grocery brand diet (GBD). Over the next 2 wk, cats consumed GBD and received metronidazole (20 mg/kg body weight twice daily). At week 4, cats were randomly allotted to one of 2 treatments [GBD; BLUE Natural Veterinary Diet GI Gastrointestinal Support (BB)] and fed for 4 wk. Fecal scores were recorded daily and fresh fecal samples were collected at weeks 2, 4, 5, 6, 7, and 8 for measurement of pH, dry matter (DM) %, metabolites, and microbiota. Microbiota was analyzed by 16S rRNA gene sequencing and qPCR, which was used to calculate dysbiosis index. Data were analyzed as repeated measures using the Mixed Models procedure of SAS 9.4, testing for effects of diet, time and diet*time. Metronidazole had dramatic effects on all outcomes, including increased fecal scores (looser stools), reduced fecal pH and DM%, reduced fecal short-chain fatty acid, branched-chain fatty acid, ammonia, phenol, and indole concentrations, and altered fecal BA concentrations (increased primary BA; reduced secondary BA). Metronidazole reduced fecal bacterial alpha diversity, increased dysbiosis index, and altered the relative abundance of 78 bacterial genera. Fecal outcomes partially recovered over the next 4 wk, with some being impacted by diet. Fecal acetate concentrations were higher after metronidazole in cats fed BB. Dysbiosis index and alpha diversity measures slowly recovered over 4 wk, without diet differences. Recovery of 16 bacterial genera was impacted by diet. Fecal BA profiles demonstrated a prolonged impairment of primary to secondary BA conversion, with cholic acid being lower after metronidazole in cats fed BB. In conclusion, our data demonstrate that metronidazole is a powerful antibiotic that has long-lasting effects on the fecal microbiota and metabolites of cats. Outcome variables slowly recovered over time, but a gastrointestinal diet may aid in recovery.

Duckweed has attracted increasing attention as a high-quality and sustainable novel plant-based protein source. However, little research has been conducted in dogs and cats. We evaluated the effects of inclusion of duckweed protein (Lemna; MCSelect; Parabel; Vero Beach, FL) primarily in replacement of pea protein in dog diets at 0%, 5%, and 10% and cat diets at %, 10%, and 15% on stool quality, nutrient digestibility, and palatability. We hypothesized that duckweed protein would be a viable protein source in both dog and cat diets by showing no detriment to nutritional outcomes. All feeding tests were conducted at an independent research facility (Susquehanna, PA). A standard 2-bowl palatability test over a 2-d period was conducted with adult animals (n = 30 each) to determine intake ratio between test diets (duckweed-containing diets) and control diets (0% duckweed protein). Apparent total tract nutrient digestibility was conducted with 18 adult dogs and 21 adult cats (n = 6 to 7 per diet) with 5 d of diet acclimation followed by 5 d of total fecal collection. Stool quality was evaluated on a 1 to 5 scale where 1 = non-formed or diarrhea and 5 = hard, formed. Palatability data were analyzed using paired t-test (daily consumption) and chi-square test (first choice). All other data were analyzed by ANOVA and contrast (SAS version 9.4). For cats, 10% duckweed had greater (P < 0.05) palatability than control, while no difference was observed between 15% duckweed protein and control. For dogs, 5% and 10% duckweed protein had (P < 0.05) lower palatability, demonstrating a preference to control. Both cats and dogs fed duckweed diets had acceptable stool quality (Mean = 3.4 and 3.3, respectively). No detriments in nutrient digestibility were observed in dogs fed 5% and 10% duckweed protein; however, cats fed 10% and 15% duckweed protein had (P < 0.05) lower dry matter, protein, and energy digestibility vs. control. In conclusion, the data collected indicate that duckweed can be a viable replacement for other plant-based proteins in dog diets at inclusion levels up to 10%; more development is needed for duckweed protein inclusion into cat diets. Duckweed, an aquatic plant rich in protein, holds promise as a sustainable plant-based protein for companion animals. However, the potential of duckweed protein in dog and cat diets has been relatively unexplored. In our study, we assessed the viability of incorporating duckweed protein into dog and cat diets by examining nutrient digestibility, stool consistency, and diet palatability. Our findings indicate that including duckweed protein in dog diets maintains acceptable nutrient digestibility and improves stool quality, although it may impact diet palatability. For cats, duckweed protein inclusion led to reduced nutrient digestibility, looser stool, and lower diet palatability. While duckweed protein shows potential as a suitable plant-based protein source for dogs, further development is necessary before considering it for cat diets.