Objective- To evaluate the effects of tylosin on C-reactive protein concentration, carriage of Salmonella enterica, and antimicrobial resistance genes in commercial pigs. Animals-120 pigs on 2 commercial farms. Procedures- A cohort of sixty 10-week-old pigs in 4 pens/farm (15 pigs/pen) was randomly selected. Equal numbers of pigs were given feed containing tylosin (40 μg/g of feed) for 0, 6, or 12 weeks. C-reactive protein concentrations were measured, microbial culture for S enterica in feces was performed, and antimicrobial resistance genes in feces were quantified. Results- No significant associations were detected between C-reactive protein concentration or S enterica status and tylosin treatment. During the 12 weeks of tylosin administration, increased levels of 6 antimicrobial resistance genes did not occur. Conclusions and Clinical Relevance-Treatment of pigs with tylosin did not affect C-reactive protein concentration or reduce carriage or load of S enterica. There was no evidence that pigs receiving tylosin had increased carriage of the 6 antimicrobial resistance genes measured. Impact for Human Medicine-S enterica is a public health concern. Use of the antimicrobial growth promoter tylosin did not pose a public health risk by means of increased carriage of S enterica.

Up to 60% of cases of equine colitis have no known cause. To improve understanding of the causes of acute colitis in horses, we hypothesized that Clostridium perfringens producing enterotoxin (CPE) and/or beta2 toxin (CPB2) are common and important causes of severe colitis in horses and/or that C. perfringens producing an as-yet-undescribed cytotoxin may also cause colitis in horses. Fecal samples from 55 horses (43 adults, 12 foals) with clinical evidence of colitis were evaluated by culture for the presence of Clostridium difficile, C. perfringens, and Salmonella. Feces were also examined by enzyme-linked immunosorbent assay (ELISA) for C. difficile A/B toxins and C. perfringens alpha toxin (CPA), beta2 toxin (CPB2), and enterotoxin (CPE). Five C. perfringens isolates per sample were genotyped for the following genes: cpa, cpb, cpb2 consensus, cpb2 atypical, cpe (enterotoxin), etx (epsilon toxin), itx (iota toxin), netB (necrotic enteritis toxin B), and tpeL (large C. perfringens cytotoxin). The supernatants of these isolates were also evaluated for toxicity for an equine cell line. All fecal samples were negative for Salmonella. Clostridium perfringens and C. difficile were isolated from 40% and 5.4% of samples, respectively. All fecal samples were negative for CPE. Clostridium perfringens CPA and CPB2 toxins were detected in 14.5% and 7.2% of fecal samples, respectively, all of which were culture-positive for C. perfringens. No isolates were cpe, etx, netB, or tpeL gene-positive. Atypical cpb2 and consensus cpb2 genes were identified in 15 (13.6%) and 4 (3.6%) of 110 isolates, respectively. All equine C. perfringens isolates showed far milder cytotoxicity effects than a CPB-producing positive control, although cpb2-positive isolates were slightly but significantly more cytotoxic than negative isolates. Based on this studied population, we were unable to confirm our hypothesis that CPE and CPB2-producing C. perfringens are common in horses with colitis in Ontario and we failed to identify cytotoxic activity in vitro in the type A isolates recovered.

The effects of heparin administration, by the oral route, were evaluated in dogs. In single and multiple dose studies (single 7.5 mg/kg, multiple 3 × 7.5 mg/kg per 48 h), plasma, urine, and fecal samples were collected at various times up to 120 h after oral administration of unfractionated heparin. Changes in plasma and urine anti-Xa activity, plasma and urine anti-IIa activity, plasma activated partial thromboplastin time (APTT) and antithrombin (ATIII), and chemical heparin in urine and feces were examined with time. There was support for heparin absorption, with significant differences in APTT, heparin in plasma as determined by anti-Xa activity (Heptest) in the single dose study and plasma anti-Xa activity, anti-IIa activity and ATIII; and chemical heparin in urine in the multiple dose study. No clinical evidence of bleeding was detected in any dog during the studies. Oral heparin therapy may be applicable for thromboembolic disease in animals. Further studies are warranted to determine the effects of oral heparin at the endothelial level in the dog.

The objective of the present work was to determine the effect of Lactobacillus murinus strain LbP2 on canine fecal immunoglobulin A (IgA) levels. Seven dogs were orally treated with a 3-mL suspension of L. murinus LbP2 containing 5 x 109 colony-forming units on alternate days for 2 wk. Six dogs were treated with 3 mL of phosphate-buffered saline as placebo. Fecal samples were taken from the rectal ampulla on days 0 and 16, and the total canine fecal IgA concentration was determined with an immunoperoxidase assay kit. The IgA levels of individual dogs were compared with the nonparametric Wilcoxon test. Differences were considered significant when the P-value was less than 0.05. An increase in the total fecal IgA concentration was observed in the 7 dogs after treatment with L. murinus LbP2 (P = 0.01796). No differences were detected between the initial total fecal IgA values and those obtained at the end of placebo treatment. Thus, after oral administration L. murinus LbP2 showed potential immunomodulatory effects, an important property to assess in a microorganism being considered for use as a probiotic.