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 dry kibble diet (GBD). Over the next 2 wk, dogs were fed GBD and received metronidazole orally (20 mg/kg BW twice daily). At wk 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 wk 2, 4, 5, 6, 7, and 8 for measurement of pH, dry matter content, and metabolite and BA concentrations. Fecal microbiota populations were analyzed by 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, change 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 wk 8, diet may be used to aid in recovery.

中文翻译：

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兽医胃肠道低脂饮食对甲硝唑治疗成年犬粪便特性、代谢物和微生物群浓度的影响


已知抗生素会导致稀便，破坏粪便微生物群，并改变狗的粪便胆汁酸 （BA） 谱。饮食可能有助于恢复，但很少进行研究。本研究的目的是确定兽医低脂饮食如何影响接受抗生素的狗的粪便特性、代谢物、BA 和微生物群。24 只健康的成年狗 [7.38 ± 1.95 岁;7.67 ± 0.76 公斤体重 （BW）] 用于一项 8 周的完全随机设计研究。在 2 周的基线期间，所有狗都喂食了领先的杂货品牌干粗磨饮食 （GBD）。在接下来的 2 周内，狗喂食 GBD 并口服甲硝唑 （20 mg/kg BW，每天两次）。在第 4 周时，将狗随机分配到两种治疗中的一种 [GBD 或 Blue Buffalo 天然兽医饮食胃肠道支持低脂 （BB）] 并喂食 4 周。每天记录粪便评分，并在第 2 、 4 、 5 、 6 、 7 和 8 周收集新鲜粪便样本，用于测量 pH 值、干物质含量、代谢物和 BA 浓度。通过 16S rRNA 基因扩增子测序和基于 qPCR 的菌群失调指数 （DI） 分析粪便微生物群群。使用 SAS 9.4 的混合模型程序对所有数据进行重复分析，测试治疗、时间和治疗*时间和显着性的影响，设置为 P<0.05。甲硝唑增加 （P<0.0001） 粪便评分 （稀便），降低粪便短链脂肪酸、支链脂肪酸、苯酚和吲哚浓度，增加初级 BA 浓度，降低次级 BA 浓度。甲硝唑还降低了粪便细菌 α 多样性，改变了 58 个细菌属的丰度，并增加了 DI。 在抗生素恢复过程中，饮食改变了粪便 pH 值、干物质百分比、代谢物和免疫球蛋白 A 浓度的变化 （P<0.05）。所有狗的粪便 BA 浓度都很快恢复。饮食影响石胆酸的变化 （P<0.0001），但其他 BA 不受影响。饮食影响超过 25 个细菌属的恢复 （P<0.05）。虽然许多细菌类群在 4 周后恢复到基线水平，但其他细菌类群并未完全恢复。所有狗的 DI 和细菌 α 多样性测量都很快恢复，但不受饮食的影响。总之，甲硝唑极大地改变了狗的粪便微生物群和代谢物。虽然大多数变量在第 8 周时恢复到基线，但饮食可用于帮助恢复。