Study and use of the probiotic Lactobacillus reuteri in pigs: a review

Probiotics are living microorganisms that provide a wide variety of health benefits to the host when ingested in adequate amounts. The bacterial strains most frequently used as probiotic agents are lactic acid bacteria, such as Lactobacillus reuteri, which is one of the few endogenous Lactobacillus species found in the gastrointestinal tract of vertebrates, including humans, rats, pigs and chickens. L. reuteri is one of the most well documented probiotic species and has been widely utilized as a probiotic in humans and animals for many years. Initially, L. reuteri was used in humans to reduce the incidence and the severity of diarrhea, prevent colic and necrotic enterocolitis, and maintain a functional mucosal barrier. As interest in alternatives to in-feed antibiotics has grown in recent years, some evidence has emerged that probiotics may promote growth, improve the efficiency of feed utilization, prevent diarrhea, and regulate the immune system in pigs. In this review, the characteristics of L. reuteri are described, in order to update the evidence on the efficacy of using L. reuteri in pigs.     

Survival and persistence of Lactobacillus plantarum 4.1 and Lactobacillus reuteri 3S7 in the gastrointestinal tract of pigs

Lactobacillus sp. are important inhabitants of the intestines of animals. They are also largely used as probiotics for both humans and animals. To exert beneficial effects, lactobacilli have to survive through the gastrointestinal transit. Based on bile-salt resistance, pH tolerance, antimicrobial activity and heat resistance, Lactobacillus plantarum 4.1 and Lactobacillus reuteri 3S7 were previously selected and used as probiotic additives in pelleted feeding trials. Both strains were fed to pigs (sows and piglets) at a cell number of ca. 10(10) viable cells per day. A polyphasic approach, comprising growth on selective media, Biolog System analysis, 16S rRNA gene sequencing and RAPD-PCR typing, was used to identify and differentiate L. plantarum 4.1 and L. reuteri 3S7 from other faecal Lactobacillus sp., L. plantarum 4.1 and L. reuteri 3S7 had the capacity to survive during the gastrointestinal transit and were found in the feaces at a cell number of 6-8 log cfu/g. Their persistence was shown after 6 days from the administration. Compared to untreated pigs, the administration of L. plantarum 4.1 and L. reuteri 3S7 significantly (P<0.05) decreased the population of Enterobacteriaceae. Besides, the beta-glucuronidase activity of all pigs decreased of ca. 23.0% during administration. The findings of this study showed that L. plantarum 4.1 and L. reuteri 3S7 have the potential to be used as probiotic additives in pelleted feed for pigs.     

鸡用益生性乳酸杆菌的研究与应用

本文对近10年来以乳酸杆菌作为鸡用益生菌的应用效果进行了综述，添加乳酸杆菌能显著提高肉鸡生长速度5％-10％（占统计数73％L2／3的试验能显著提高饲料效率，但幅度相差较大（从2．5％到30％）。多数报道认为能提高机体免疫力、抑制病，原菌的致病性，降低鸡的死亡率。乳酸杆菌对产蛋鸡生产性能的影响较稳定。     

罗伊乳杆菌优化培养及产乳酸效果研究

采用玉米浆和液化玉米做氮源和碳源培养乳酸菌,降低乳酸菌培养和乳酸生产成本。试验以玉米浆的用量(3%、4%、5%、6%、7%)和碳氮比(3.5、4、4.5、5、5.5)为试验因素进行双因素试验设计,共25组试验,每组3个重复。以实验室培养的乳酸菌作为出发菌种,按照5%接种量接种到改良培养基,37℃厌氧培养28 h后,对25组试验的乳酸含量、乳酸菌数目进行检测。结果显示,玉米浆浓度对乳酸菌培养过程中的乳酸含量、乳酸菌数目的影响差异显著(P0.05),玉米浆用量在4%～6%时对罗伊乳杆菌的活菌数和乳酸产量有较好的影响;碳氮比对乳酸含量和乳酸菌数目的影响差异显著(P0.05),且碳氮比为4时,罗伊乳杆菌菌数最高。结论:液化玉米和玉米浆合理调配碳氮比,可达到廉价培养罗伊乳酸杆菌并低成本生产乳酸的目的。     

Lactobacillus reuteri ATCC 55730 and L22 display probiotic potential in vitro and protect against Salmonella-induced pullorum disease in a chick model of infection

Lactobacillus reuteri ATCC 55730 (L. reuteri ATCC 55730) and L. reuteri L22 were studied for their probiotic potential. These two strains were able to produce an antimicrobial substance, termed reuterin, the maximum production of reuterin by these two strains was detected in the late logarithmic growth phase (16 h in MRS and 20 h in LB broths). These two strains could significantly reduce the growth of Salmonella pullorum ATCC 9120 in MRS broth, L. reuteri ATCC 55730 with a reduction of 48.2 ± 4.15% (in 5 log) and 89.7 ± 2.59% (in 4 log) respectively, at the same time, L. reuteri L22 was 69.4 ± 3.48% (in 5 log) and 80.4 ± 3.22% respectively. L. reuteri ATCC 55730 was active against the majority of the pathogenic species, including S. pullorum ATCC 9120 and Escherichia coli O₇₈, while L. reuteri L22 was not as effective as L. reuteri ATCC 55730. The two potential strains were found to survive variably at pH 2.5 and were unaffected by bile salts, while neither of the strains was haemolytic. Moreover, L. reuteri ATCC 55730 exhibited variable susceptibility towards commonly used antibiotics; but L. reuteri L22 showed resistant to most antibiotics in this study. L. reuteri ATCC 55730 consequently was found to significantly increase survival rate in a Salmonella-induced pullorum disease model in chick. To conclude, strain L. reuteri ATCC 55730 possesses desirable probiotic properties, such as antimicrobial activity and immunomodulation in vitro, which were confirmed in vivo by the use of animal models.     

Evaluation of an intestinal Lactobacillus reuteri strain expressing rumen fungal xylanase as a probiotic for broiler chickens fed on a wheat-based diet

1. This study was conducted to evaluate the feasibility of using a transformed Lactobacillus reuteri Pg4 strain harbouring a rumen fungal xylanase gene as a probiotic supplement in a wheat-based poultry diet. 2. A total of 400 broiler chicks was allocated to two treatment groups with or without supplementation with 10(6) colony forming units (cfu)/g of transformed L. reuteri Pg4 in a wheat-based regimen to investigate the performance, intestinal microflora populations, digesta viscosity and excreta ammonia concentrations in these broiler chickens. 3. Supplementation of the wheat-based diet with transformed L. reuteri Pg4 decreased intestinal viscosity, caecal coliform population, and increased body weight gain and ileal villus height and crypt depth from 0 to 21 d of age. It also decreased excreta ammonia concentrations, and increased the caecal total volatile fatty acid (VFA) and lactic acid concentrations from 0 to 21 d and 22 to 37 d of age. 4. Further, it was demonstrated that 40% of the Lactobacillus cells randomly isolated from the digesta of the ileum and caecum of the supplemented group possessed xylanase secretion capability. 5. It appears reasonable to assume, therefore, that the derived benefit is a result of the organism surviving, and the associated performance of some function in the intestinal tract which benefits gut health.     

Aquaculture and stress management: a review of probiotic intervention

To meet the ever‐increasing demand for animal protein, aquaculture continuously requires new techniques to increase the production yield. However, with every step towards intensification of aquaculture practices, there is an increase in stress level on the animal as well as on the environment. Feeding practices in aqua farming usually plays an important role, and the addition of various additives to a balanced feed formula to achieve better growth is a common practice among the fish and shrimp culturists. Probiotics, also known as ‘bio‐friendly agents’, such as LAB (Lactobacillus), yeasts and Bacillus sp., can be introduced into the culture environment to control and compete with pathogenic bacteria as well as to promote the growth of the cultured organisms. In addition, probiotics are non‐pathogenic and non‐toxic micro‐organisms, having no undesirable side effects when administered to aquatic organisms. Probiotics are also known to play an important role in developing innate immunity among the fishes, and hence help them to fight against any pathogenic bacterias as well as against environmental stressors. The present review is a brief but informative compilation of the different essential and desirable traits of probiotics, their mode of action and their useful effects on fishes. The review also highlights the role of probiotics in helping the fishes to combat against the different physical, chemical and biological stress.     

Testing two Lactobacillus plantarum and Lactobacillus acidophilus strains for their suitability as a lipoid probiotic

Two strains of lactobacilli (Lactobacillus acidophilus T-135 and Lactobacillus plantarum 4/97) were selected in order to study their inhibitory properties against frequent udder pathogens (Escherichia coli, Staphylococcus aureus, Streptococcus agalactiae, Streptococcus uberis, Salmonella enteritidis and Bacillus pumilus), their production of organic acids as well as their ability to survive on the teat skin, the teat duct mucosa and in a lipoid emulsion. Both strains inhibited the tested pathogenic microbes and survived on the investigated surfaces and in an emulsion for more than 6 hours and 11 days, respectively.     

Pneumonia of pigs: a review

Pneumonia of pigs is one of the more important disease factors limiting pig production. Of the varieties of pneumonia affecting this species enzootic pneumonia caused by Mycoplasma spp. is the most common and most important. The major effects of this disease are lowered food conversion ratio and poor weight gain. Deaths are usually the result of secondary infection by necrotising, pus-forming bacteria. Eradication of the disease is expensive and requires depopulation and restocking. Control and treatment by antimicrobial agents is most effective if the drug combination used takes regard of the bacteria complicating the disease on any particular property. Other forms of pneumonia such as those caused by Haemophilus pleuropneumoniae, Salmonella cholerae-suis and Aujeszky's disease virus can be important on individual farms. The role of other agents such as Bordetella bronchiseptica and adenoviruses in respiratory disease of pigs remain to be clarified.     

Experimental evaluation of foot-and-mouth disease vaccines for emergency use in ruminants and pigs: a review

Changes to foot-and-mouth disease (FMD) control policies since 2001 mean that emergency vaccination must be considered more readily as a control measure in the future. Since field application of vaccine for emergency use has only rarely been applied, the effectiveness of single dose administration, as a control measure in an outbreak situation, is poorly understood. In this review we consider all the available experimental data from studies utilizing either experimental or readily available, commercially produced vaccines, in order to assess their likely effectiveness as an additional means of controlling FMD transmission and spread in an emergency. Overall it is concluded that such vaccines offer an additional and valuable means of FMD control for both ruminants and pigs. They are able to reduce clinical disease, sub-clinical infection and excretion and onward transmission of virus. However, to be most effective, vaccination should be rapidly applied to give maximum opportunity for immunity to develop. We also identify areas for future research and emphasize the importance of vaccine efficacy studies in providing data for models that can help to predict the efficacy of differing FMD control strategies.     

Pneumonia of pigs: a review

Pneumonia of pigs is one of the more important disease factors limiting pig production. Of the varieties of pneumonia affecting this species enzootic pneumonia caused by Mycoplasma spp. is the most common and most important. The major effects of this disease are lowered food conversion ratio and poor weight gain. Deaths are usually the result of secondary infection by necrotising, pus-forming bacteria. Eradication of the disease is expensive and requires depopulation and restocking. Control and treatment by antimicrobial agents is most effective if the drug combination used takes regard of the bacteria complicating the disease on any particular property. Other forms of pneumonia such as those caused by Haemophilus pleuropneumoniae, Salmonella cholerae-suis and Aujeszky’s disease virus can be important on individual farms. The role of other agents such as Bordetella bronchiseptica and adenoviruses in respiratory disease of pigs remain to be clarified.     

Lactobacillus rhamnosus strain GG is a potential probiotic for calves

Diarrhea is a common occurrence in neonatal calves. Several veterinary probiotics claiming to prevent or treat calf diarrhea are available, but have not been well studied. This study assessed the capability of Lactobacillus rhamnosus strain GG (LGG) to maintain viability in the gastrointestinal tract of calves. We also determined whether LGG can be administered in an oral rehydration solution (ORS) without compromising the efficacy of the ORS or the viability of LGG, and whether LGG produces D-lactate or not. To investigate the intestinal survival of LGG, 15 calves were randomized into 3 groups and LGG was administered orally with their morning milk feeding on 3 consecutive days at a low (LD), medium (MD), or high (HD) dosage. Fecal samples were collected on days 0 (control), 1, 2, 3, 5, and 7 and incubated for 72 h on deMan, Rogosa, Sharpe agar. Twenty-four hours after the 1st feeding, LGG was recovered from 1 out of 5 calves in the LD group, 4 out of 5 calves in the MD group, and 5 out of 5 calves in the HD group. To determine if LGG caused the glucose levels in the ORS to drop below effective levels, 1.5 L of the ORS was incubated with LGG for 2 h at 37 degrees C and the glucose concentration was measured every 20 min using a glucose meter. This ORS was then further incubated for 10 h and aliquots analyzed by high performance liquid chromatography to determine if D-lactate was produced by LGG. Glucose concentrations did not change over the 2 h of incubation, and no D-lactate was produced after 48 h. The LGG maintained viability in ORS. Therefore, this study demonstrated that LGG survives intestinal transit in the young calf, produces no D-lactate, and can be administered in an ORS.     

Effect of Lactobacillus reuteri on the Expression Profile of miRNAs in the Jejunum of Piglets

This study was conducted to investigate the effect of Lactobacillus reuteri on the expression of miRNAs in the jejunum of piglets. Six litters of healthy 1-day-old York×Rongchang piglets were selected and randomly divided into the two group,3 litters per group(n=27). The two groups were control group (daily orally adminitrated with 0.1% sterile peptone solution per piglet),and the LR group (daily orally administrated with 1.0×10¹⁰ CFU of L. reuteri per piglet), respectively. At 10 and 20 days of age, six piglets per group were selected for slaughter, respectively, and the jejunum samples were collected. After RNA extraction, the library was constructed and the miRNA expression profile of the jejunum was detected by Solexa high-throughput sequencing technology. Bioinformatics technology was used to conduct target genes prediction and functional analysis. The results showed that: 1) A total of 8 libraries were constructed and a total of 187 103 840 clean reads were obtained, of which the 22 nt length sequence accounted for the largest proportion; 2) Three hundred and fifty-four and 352 known miRNAs were respectively identified at 10 and 20 days of age, of which 329 miRNAs were co-expressed; 3) Differentially expressed (DE) miRNAs in the jejunum were found after L. reuteri administration, 7 and 9 DE miRNAs were obtained at 10 and 20 days of age,respectively. Notably, ssc-miR-218 was expressed differentially at two ages. 4) KEGG pathway analysis and target gene prediction on the differentially expressed miRNAs revealed that 10 221 target genes were enriched in 293 biological pathways, of which 66 were significantly enriched (P<0.05), including the MAPK signaling pathway and PI3K-Akt signaling pathway, which were known to regulate intestinal development and immune. 5) Six miRNAs were selected to validate the sequencing results by qRT-PCR, the qRT-PCR expression results corresponded well with those from the sequencing. The results indicates that L. reuteri may regulate intestinal health related pathways by influencing the expression of jejunal miRNAs.     

罗伊氏乳杆菌对仔猪空肠miRNAs表达谱的影响

试验旨在研究罗伊氏乳杆菌对仔猪空肠miRNAs表达的影响。选用1日龄健康约克×荣昌仔猪6窝,随机分为两组,每组3窝（共27头）。即对照组（每天每头灌喂0.1%的无菌蛋白胨溶液）,LR组（每天每头灌喂活菌总数为1.0×10¹⁰CFU的罗伊氏乳杆菌）,分别在10和20日龄,每组选取6头进行屠宰,采集空肠样品。通过Solexa高通量测序技术检测空肠miRNA的表达谱,利用生物信息学技术进行靶基因预测和功能分析。结果显示：1）试验构建了8个文库,共获得187 103 840条纯净reads序列,其中22 nt长度序列占的比例最大;2）10和20日龄分别鉴定出354和352个已知的miRNAs,其中有329个miRNAs共表达;3）灌喂罗伊氏乳杆菌组仔猪空肠miRNA差异表达,10和20日龄分别获得7和9个差异显著的miRNAs,ssc-miR-218在两个日龄中都差异表达;4）对差异表达的miRNAs进行靶基因预测和KEGG通路分析,发现有10 221个靶基因富集到293条通路上,有66条通路显著富集（P<0.05）,包括与肠道发育及免疫调控相关的MAPK和PI3K-Akt信号通路;5）随机挑选6个差异表达miRNAs进行荧光定量PCR验证,验证结果与测序结果基本一致。本研究表明,罗伊氏乳杆菌可能通过影响空肠miRNAs表达来调控有关肠道健康的信号通路。     

Effects of Lactobacillus acidophilus DSM13241 as a probiotic in healthy adult cats

OBJECTIVE: To evaluate the effect of dietary supplementation with the probiotic strain Lactobacillus acidophilus DSM13241 in healthy adult cats. ANIMALS: 15 adult cats. PROCEDURES: Cats were fed a nutritionally complete dry food for 5 weeks. Fecal character was assessed daily, and a single fecal sample and 3-mL blood sample were collected for bacterial enumeration and hematologic analysis, respectively. Cats were then fed the same diet supplemented with L acidophilus DSM13241 (2 x 10(8) CFU/d) for 4.5 weeks. Repeat fecal and hematologic measurements were taken prior to the return to control diet for a 4-week period. RESULTS: The probiotic species was recovered from feces, demonstrating survival through the feline gastrointestinal tract. Probiotic supplementation was associated with increased numbers of beneficial Lactobacillus and L acidophilus groups in feces and decreased numbers of Clostridium spp and Enterococcus faecalis, indicating an altered bacterial balance in the gastrointestinal tract microflora. Fecal pH was also decreased suggesting a colonic environment selective for the beneficial lactic acid bacterial population. Systemic and immunomodulatory effects were associated with administration of L acidophilus DSM13241 including altered cell numbers within WBC subsets and enhanced phagocytic capacity in the peripheral granulocyte population. In addition, plasma endotoxin concentrations were decreased during probiotic feeding, and RBCs had a decreased susceptibility to osmotic pressure. CONCLUSIONS AND CLINICAL RELEVANCE: Probiotic strain L acidophilus DSM13241 fed at 2 x 10(8) CFU/d can alter the balance of gastrointestinal microflora in healthy cats. Furthermore, administration of this probiotic results in beneficial systemic and immunomodulatory effects in cats.     

Preliminary evaluation of Lactobacillus rhamnosus strain GG,a potential probiotic in dogs

Lactobacillus rhamnosus strain GG (LGG) has been studied extensively as a probiotic in humans. However, the ability of an organism to survive passage through the intestinal tract and exert beneficial effects cannot be directly extrapolated between species. This study evaluated the ability of LGG to survive gastrointestinal transit in dogs and assessed whether oral administration of LGG is safe, in order to determine whether studies evaluating the efficacy of LGG in the treatment of canine disease are indicated. Dogs were divided into 5 groups receiving doses of 0 (control group, n = 4), 1 x 10(9) (group 1, n = 8), 1 x 10(10) (group 2, n = 8), 5 x 10(10) (group 3, n = 8) and 5 x 10(11) (group 4, n = 4) colony forming units per day, orally, for 5 days. Lactobacillus rhamnosus GG was detected in the feces of 4/8 dogs in groups 1 and 2, 5/8 dogs in group 3, 4/4 dogs in group 4, and 0/4 dogs in the control group. Fecal colonization was significantly greater in group 4 than in any other group (P < 0.001). Differences between groups 1, 2, and 3 were not significant. No adverse effects were noted. Fecal colonization of LGG in dogs is somewhat variable; however, clinical studies are indicated to evaluate this organism in the treatment and prevention of canine disease.     

Effects of Lactobacillus reuteri Supplementation on Inhibition of Pathogenic Escherichia coli in Kunming Mice

This study was aimed to explore the effect,dose of Lactobacillus reuteri on inhibition of pathogenic Escherichia coli infection on Kunming mice as well as its potential mechanism. 96 Kunming mice were randomly allocated into four groups with 4 replicates per group and 6 mice per replicate,which were control group,low dose group,middle dose group and high dose group. All of the mice feed commercial basal feedstuff,meanwhile the mice in control group drank tap-water,three treatments were supplemented with 1.0×10⁶,1.0×10⁷ and 1.0×10⁸ CFU/mL Lactobacillus reuteri in water. The feeding period was 28 days. All the mice were weighted, and the ADFI,ADG and F/G were calculated at the end of experiment.At the day of 28,pathogenic Escherichia coli (4.98×10⁹ CFU/mL) were irrigated to study the mortality. The indexes of intestinotoxin and antioxidation in serum and cecal microbacteria were inspected.The results indicated that supplemented with middle dose of Lactobacillus reuteri could significantly improve the final body weight,ADG compared with the control (P<0.05). The mortality, serum intestinotoxin level and MDA concentration,Escherichia coli and Staphylococcus were significantly lower than control group (P<0.05),while the T-SOD,T-AOC,GSH-Px,Lacobacillus and Bifidobacterium were significantly improved (P<0.05).In conclusion,with Lactobacillus reuteri supplementation,the growth performance was improved and antioxidant capacity and cecal microbacteria were enhanced after pathogenic Escherichia coli infected, mouse mortality caused by the pathogenic Escherichia coli was effectively reduced,and the effect of 1.0×10⁷ CFU/mL Lactobacillus reuteri was the best.     

Stress and its influence on reproduction in pigs: a review

The manifestations of stress, defined as a biological response to an event that the individual perceives as a threat to its homeostasis, are commonly linked to enhanced activity of the hypothalamo-pituitary-adrenal (HPA) axis and the activation of the sympathetic adreno-medullary (SA) system. Activation of the HPA system results in the secretion of peptides from the hypothalamus, principally corticotropin releasing hormone (CRH), which stimulates the release of adrenocorticotropic hormone (ACTH) and beta-endorphin. ACTH induces the secretion of corticosteroids from the adrenal cortex, which can be seen in pigs exposed to acute physical and/or psychological stressors. The present paper is a review of studies on the influence of stressors on reproduction in pigs. The effects of stress on reproduction depend on the critical timing of stress, the genetic predisposition to stress, and the type of stress. The effect of stress on reproduction is also influenced by the duration of the responses induced by various stressors. Prolonged or chronic stress usually results in inhibition of reproduction, while the effects of transient or acute stress in certain cases is stimulatory (e.g. anoestrus), but in most cases is of impairment for reproduction. Most sensitive of the reproductive process are ovulation, expression of sexual behaviour and implantation of the embryo, since they are directly controlled by the neuroendocrine system.     

罗伊氏乳杆菌抑制致病性大肠杆菌感染效果的研究

本研究旨在探索益生罗伊氏乳杆菌抑制致病性大肠杆菌感染昆明鼠的效果、剂量及潜在机制。将96只昆明鼠随机分为4个组,每组4个重复,每个重复6只,分别为对照组、低剂量组、中剂量组和高剂量组。昆明鼠饲喂商品化基础日粮,对照组饮用自来水,低、中、高剂量组在饮水中分别添加1.0×10⁶、1.0×10⁷及1.0×10⁸ CFU/mL罗伊氏乳杆菌。试验期为28 d,试验结束后称重,计算昆明鼠平均日采食量（ADFI）、平均日增重（ADG）及料重比（F/G）;并灌胃致病性大肠杆菌（4.98×10⁹ CFU/mL）,观察小鼠死亡率;检测血清大肠杆菌肠毒素含量、抗氧化能力及肠道菌群数量。结果显示,中剂量组小鼠末重和平均日增重均显著高于对照组（P<0.05）,小鼠死亡率、血清大肠杆菌肠毒素浓度和丙二醛（MDA）水平均显著低于对照组（P<0.05）。中剂量组血清总超氧化物歧化酶（T-SOD）、谷胱甘肽过氧化物酶（GSH-Px）和总抗氧化力（T-AOC）活力均显著高于对照组（P<0.05）,总乳杆菌和双歧杆菌数量显著提高（P<0.05）,大肠杆菌和沙门氏菌含量显著降低（P<0.05）。综上,在小鼠饮水中添加罗伊氏乳杆菌可提高生长性能,改善攻毒后机体抗氧化力和盲肠菌群结构,降低血清大肠杆菌肠毒素含量和小鼠死亡率,有效降低致病性大肠杆菌的感染造成的死亡率,其中添加1.0×10⁷ CFU/mL伊氏乳杆菌效果最好。     

Effects of probiotic Lactobacillus acidophilus strain DSM13241 in healthy adult dogs

OBJECTIVE: To evaluate viability of a probiotic strain of Lactobacillus acidophilus in a dry dog food, determine its ability to survive transit through the gastrointestinal tract and populate the colon, and assess its effects on intestinal and systemic parameters. ANIMALS: 15 adult dogs. PROCEDURE: Dogs were sequentially fed a dry control food for 2 weeks, the same food supplemented with > 10(9) L. acidophilus for 4 weeks, and the control food again for 2 weeks. Fecal score was assessed daily, and fecal and blood samples were collected for enumeration of bacterial populations and measurement of hematologic variables. RESULTS: Recovery of L. acidophilus from the supplemented food was 71% and 63% at the start and end of the study, respectively, indicating that the bacteria were able to survive manufacture and storage. The probiotic bacterium was detected in feces via ribotyping and RNA gene sequencing during the probiotic administration phase but not 2 weeks after cessation of administration. Administration of the probiotic-supplemented food was associated with increased numbers of fecal lactobacilli and decreased numbers of clostridial organisms. There were significant increases in RBCs, Hct, hemoglobin concentration, neutrophils, monocytes, and serum immunoglobin G concentration and reductions in RBC fragility and serum NO concentration. CONCLUSIONS AND CLINICAL RELEVANCE: These data indicate that L. acidophilus can be successfully incorporated into a dry dog food, survive transit through the canine gastrointestinal tract, and populate the colon and are associated with local and systemic changes. This probiotic bacterium may have the potential to enhance intestinal health and improve immune function in dogs.