Screening of the equine intestinal microflora for potential probiotic organisms

REASONS FOR PERFORMING STUDY: Probiotics have not been demonstrated to provide any beneficial health effects in horses, possibly because of improper selection of probiotic organisms. This study was designed to identify lactic acid bacteria of equine origin with predetermined beneficial properties which might make them useful as therapeutic probiotics. HYPOTHESIS: A small percentage of lactic acid bacteria that are native to the intestinal tract of horses possess properties that may be useful in the treatment and/or prevention of gastrointestinal disease in horses. METHODS: Faecal samples were collected from healthy mature horses and foals. Lactic acid bacteria were isolated and tested for the ability to grow in acid and bile environments, aerotolerance and in vitro inhibition of enteropathogens. One isolate that possessed these properties was administered orally to healthy mature horses and foals and gastrointestinal survival was assessed. RESULTS: Of the 47 tested organisms, 18 were deemed to be adequately acid- and bile-tolerant. All were aerotolerant. Four organisms markedly inhibited Salmonella spp. One isolate, Lactobacillus pentosus WE7, was subjectively superior and chosen for further study. It was also inhibitory against E. coli, moderately inhibitory against S. zooepidemicus and C. difficile and mildly inhibitory against C. perfringens. After oral administration, this isolate was recovered from the faeces of 8/9 (89%) foals and 7/8 (87.5%) mature horses. CONCLUSIONS: Lactobacillus pentosus WE7 possesses in vitro and in vivo properties that may be useful for the prevention and treatment of enteric disease in horses. POTENTIAL RELEVANCE: The beneficial in vitro and in vivo properties that L. pentosus WE7 possesses indicate that randomised, blinded, placebo-controlled efficacy studies are warranted.     

Effect of plasma transfusion on neutrophil function in healthy and septic foals

OBJECTIVE: To evaluate the effect of plasma transfusion on phagocytosis and oxidative burst activity of peripheral blood neutrophils from healthy and septic equine neonates with sub-optimal passive transfer of maternal immunity. ANIMALS: Nine healthy and seven septic foals with suboptimal passive transfer of maternal immunity (serum IgG < 8 g/L) presented to participating veterinary hospitals for plasma transfusion, and seven healthy foals less than 7 days of age and with circulating IgG concentrations > or = 8 g/L. PROCEDURE: Foals with serum IgG concentrations < 8 g/L were assessed as healthy or septic. Sepsis was recognised by positive bacterial cultures and/or sepsis scores of > or = 11. All foals received between 1 and 3 L of plasma to boost circulating IgG concentrations to > or = 8 g/L. Serum IgG concentrations were determined before and following transfusion by glutaraldehyde coagulation test and confirmed by single radial immunodiffusion assays. Neutrophil phagocytosis and oxidative burst activity were determined before plasma transfusion and at 0 h, 12 h, 24 h, 48 h and 5 d following treatment. Neutrophil function from seven healthy foals less than 7 d of age and with circulating IgG concentrations of > or = 8 g/L was similarly evaluated on a single occasion. RESULTS: Plasma treatment significantly increased circulating IgG concentrations for healthy and septic foals. Oxidative burst activity of neutrophils from septic foals was significantly increased 5 days following treatment, relative to 0 h post treatment. Other differences were not significant but suggested a transient decrease in phagocytosis by neutrophils from healthy foals and increased phagocytosis by neutrophils from septic foals immediately following transfusion. Oxidative burst activity of neutrophils from septic foals tended to be less than that of healthy foals at all sampling times. Serum IgG concentrations were not correlated with neutrophil phagocytosis, but were correlated with oxidative burst activity. CONCLUSIONS: Plasma transfusion did not improve neutrophil function of healthy foals, suggesting that such treatment may be of equivocal benefit for healthy neonates. Conversely, improved neutrophil function was observed following treatment of septic foals, suggesting that plasma transfusion was beneficial for these foals. Oxidative burst activity of neutrophils from septic foals was lower than that of neutrophils from healthy foals and was significantly improved 5 days post treatment, when compared with values obtained immediately following treatment.     

Oral Infection of Weanling Foals with an Equine Isolate of Lawsonia intracellularis,Agent of Equine Proliferative Enteropathy

Background: Equine proliferative enteropathy (EPE) is an emerging disease of weanling foals. Objectives: Describe clinical, hematologic, biochemical, serologic, molecular, and ultrasonographic findings in foals experimentally infected with Lawsonia intracellularis. Animals: Eight foals. Methods: Recently weaned foals were assigned to either the challenge (n = 3), the sentinel (n = 3), or the control (n = 2) group. Foals were experimentally challenged via intragastric inoculation of 3 × 10¹⁰L. intracellularis organisms grown in culture. Each experimentally infected foal was housed with a sentinel foal in order to assess feco‐oral transmission. All foals were monitored daily for the development of clinical abnormalities and were weighed once weekly for the duration of the study (90 days). Abdominal ultrasound examination was performed weekly. Feces were collected every other day for 60 days, then weekly for an additional 30 days for the quantitative molecular detection of L. intracellularis. Blood was collected weekly for hematologic, biochemical, and serologic analysis. Results: Only challenged foals developed transient clinical signs of EPE consisting of anorexia, lethargy, fever, loose feces, and peripheral edema. Two challenged foals developed transient hypoalbuminemia. Fecal shedding of L. intracellularis was first detected in the challenged foals between days 12 and 18 postinoculation and lasted for 7–21 days. Seroconversion was documented in all challenged foals and in 1 sentinel foal. The remaining sentinel and control foals remained unaffected. Conclusions and Clinical Importance: Clinical EPE of variable severity was induced in all foals infected with L. intracellularis. Furthermore, L. intracellularis can be transmitted via the feco‐oral route to susceptible herdmates.     

Characterization of Clostridium difficile isolates from foals with diarrhea: 28 cases (1993-1997)

OBJECTIVE: To determine molecular characteristics of Clostridium difficile isolates from foals with diarrhea and identify clinical abnormalities in affected foals. DESIGN: Retrospective study. ANIMALS: 28 foals with C difficile-associated diarrhea. PROCEDURE: Toxigenicity, molecular fingerprinting, and antibiotic susceptibility patterns were determined. Information on signalment, clinical findings, results of clinicopathologic testing, whether antimicrobials had been administered prior to development of diarrhea, and outcome was obtained from the medical records. RESULTS: Twenty-three (82%) foals survived. Toxin A and B gene sequences were detected in isolates from 24 of 27 foals, whereas the toxin B gene alone was detected in the isolate from 1 foal. Results of an ELISA for toxin A were positive for fecal samples from only 8 of 20 (40%) foals. Ten of 23 (43%) isolates were resistant to metronidazole. Molecular fingerprinting revealed marked heterogeneity among isolates, except for the metronidazole-resistant isolates. Sixteen foals had tachypnea. Hematologic abnormalities were indicative of inflammation. Common serum biochemical abnormalities included metabolic acidosis, hyponatremia, hypocalcemia, azotemia, hypoproteinemia, hyperglycemia, and high enzyme activities. Passive transfer of maternal antibodies was adequate in all 12 foals evaluated. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that a large percentage of C difficile isolates from foals with diarrhea will have the toxin A and B gene sequences. Because of the possibility that isolates will be resistant to metronidazole, susceptibility testing is warranted. Clostridium difficile isolates from foals may have a substantial amount of molecular heterogeneity. Clinical and hematologic findings in affected foals are similar to those for foals with diarrhea caused by other pathogens.     

Effects of inactivated parapoxvirus ovis on the cumulative incidence of pneumonia and cytokine secretion in foals on a farm with endemic infections caused by Rhodococcus equi

The objectives of the present study were to determine if administration of inactivated parapoxvirus ovis (IPPVO) can decrease the cumulative incidence of pneumonia and increase the number of IFN-γ- and IL-4-secreting cells among foals. Fifty-nine foals were randomly assigned to 2 treatment groups (IPPVO or placebo) prior to birth. At 24-48 h of age, foals received 2 ml of either IPPVO or a placebo by intramuscular injection. Injections were repeated 24h and 8 days later. The number of IFN-γ- and IL-4-secreting cells was measured using a validated ELISPOT assay on blood mononuclear cells collected when the foals were 1-14 days old. Foals were monitored daily for clinical signs of pneumonia and biweekly for lung lesions by ultrasonography. The proportion of foals that developed clinical or ultrasonographic evidence of pneumonia was not significantly different between IPPVO (16 of 28) and placebo (14 of 31). IFN-γ- and IL-4-secreting cells were detected in only 22 and 15 foals, respectively. There was a significant effect of treatment with IPPVO on the number of IFN-γ secreting cells in foals 7- to 14-days-old but not in younger foals. There was no significant effect of treatment with IPPVO on the number of IL-4-secreting cells. The odds of detecting IFN-γ (5.1; 95% CI: 1.5-15) and IL-4 (3.5; 95% CI: 1.1-12) were significantly higher in foals 7-14 days than in younger foals regardless of treatment group. There was no significant association between IFN-γ or IL-4 secretion early in life and subsequent development of pneumonia.     

Clinical and pathological effects of flunixin meglumine administration to neonatal foals.

The effects of daily intravenous administration of flunixin meglumine at dosages of 0.55, 1.1, 2.2 and 6.6 mg/kg for five days were examined in neonatal foals. Six two day old foals were used to evaluate the effect of each dosage. Foals were examined every day and blood samples collected on days 1, 3 and 6. All foals were euthanized after six days, necropsied and examined for lesions. The major clinical abnormality was diarrhea, but the incidence was not related to the dosage of flunixin meglumine administered. The foals receiving 6.6 mg/kg of flunixin meglumine had significantly more gastrointestinal ulceration and greater cecal pathology and cecal petechiation scores than those foals treated with saline. The foals in the 6.6 mg/kg treatment group had a greater loss of total protein during the study, but the difference was not significant. There were no statistically significant blood cellular or biochemical alterations associated with the administration of flunixin meglumine. There were no significant clinicopathological differences between healthy foals treated with the recommended dosage of flunixin meglumine and those treated with physiological saline.     

Experimental Clostridium difficile enterocolitis in foals

Despite empirical clinical association of infection with Clostridium difficile with colitis in horses, a causal link has not been confirmed. The objective of this study was to develop a model of C. difficile-associated diarrhea in foals with normal transfer of passive immunity. Nine 1-day-old pony foals were inoculated intragastrically with spores or vegetative cells of C. difficile. Five foals were challenged with spores, with 2 receiving 10(5) colony-forming units (CFUs) and concurrently 3 receiving 10(7) CFUs once daily for 3 days. Clindamycin was administered orally to disrupt gastrointestinal flora. A further 4 foals were challenged by orogastric administration of 10(10) CFUs of vegetative cells once daily for 3 days or until diarrhea developed. This group did not receive clindamycin. Spore and vegetative cell preparations were negative for toxins of C. difficile and common enteropathogens. Clinical signs varied from mild abdominal discomfort and pasty feces to colic and watery diarrhea in 8 of 9 foals. Four of 5 foals challenged with spores developed mild diarrhea, whereas all foals challenged with vegetative cells developed moderate to severe diarrhea. C. difficile was isolated from feces of all foals between 24 and 72 hours after inoculation and toxins A or B or both were detected in the feces of all foals by an enzyme-linked immunosorbent assay. We concluded that spores and vegetative cells of C. difficile are capable of colonizing the gastrointestinal tract, producing toxins, and inducing clinical signs similar to those encountered in naturally occurring cases. This study fulfilled Koch's postulates for C. difficile-associated diarrhea in foals and provides a model for consistent reproduction of the disease for future studies.     

Risk of adverse effects in pneumonic foals treated with erythromycin versus other antibiotics: 143 cases (1986-1996)

OBJECTIVE: To determine whether foals with pneumonia that were treated with erythromycin, alone or in combination with rifampin or gentamicin, had a higher risk of developing adverse effects, compared with foals treated with trimethoprim-sulfamethoxazole (TMS), penicillin G procaine (PGP), or a combination of TMS and PGP (control foals). DESIGN: Retrospective study. ANIMALS: 143 foals < 240 days old. PROCEDURE: Information on age, sex, breed, primary drug treatment, total days of treatment with the primary drug, and whether the foal developed diarrhea, hyperthermia, or respiratory distress was obtained from the medical records. Relative risk (RR) and attributable risk (AR) were calculated to compare risk of adverse reactions between foals treated with erythromycin and control foals. RESULTS: Only 3 (4.3%) control foals developed diarrhea; none developed hyperthermia or respiratory distress. Foals treated with erythromycin had an 8-fold risk (RR, 8.3) of developing diarrhea, compared with control foals, and increased risks of hyperthermia (AR, 25%) and respiratory distress (AR, 15%). CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that use of erythromycin to treat foals with pneumonia was associated with an increased risk of diarrhea, hyperthermia, and respiratory distress, compared with use of TMS or PGP.     

Effect of a Probiotic on Prevention of Diarrhea and Clostridium difficile and Clostridium perfringens Shedding in Foals

Background

Up to 60% of foals develop diarrhea within 6 months after birth. Preventive measures are limited but potentially probiotics could be used.

Objective

To evaluate the effect of a newly designed probiotic on the incidence of foal diarrhea in a randomized field trial.

Animals

Seventy‐two healthy neonatal foals.

Methods

Randomized, placebo‐controlled field trial. Foals were administered a placebo or probiotic for 3 weeks and monitored for an additional week. A total of 3 fecal samples were taken from each foal at biweekly intervals. Statistical modeling was applied for comparison of incidence and duration of diarrhea and fecal shedding of Clostridium perfringens and Clostridium difficile between treatment and age groups.

Results

The overall incidence of diarrhea was 41 of 72 (59%) and did not differ (P = 0.37) between treatment groups. Foals treated with probiotics were more likely to develop diarrhea requiring veterinary intervention (P = 0.007). Age had a significant effect on incidence of diarrhea (P < 0.001); foals 8–15 days old having the highest probability of developing diarrhea. Duration of diarrhea and soft feces were not significantly different between groups. The prevalence of C. perfringens shedding was 55% with no difference between treatment groups (P = 0.23). The prevalence of C. difficile shedding was 11%.

Conclusion and Clinical Importance

There was no benefit of administering a 3‐week course of probiotics, but potential adverse effects were noted. Whether the probiotics lacked a clinical effect, or the choice of strains or dose was inadequate, is unknown. Clostridial shedding was not influenced by probiotics despite in vitro activity of probiotics.     

Factors associated with Salmonella shedding among equine colic patients at a veterinary teaching hospital

OBJECTIVE: To evaluate factors potentially associated with fecal Salmonella shedding among equine patients hospitalized for colic at a veterinary teaching hospital and to determine the effects of probiotic treatment on fecal Salmonella shedding and clinical signs. DESIGN: Longitudinal study and controlled trial. ANIMALS: 246 equine colic patients. PROCEDURE: History and medical information were obtained from patient records. Fecal and environmental samples were submitted for aerobic bacterial culture for Salmonella enterica. Fifty-one patients were treated with a commercially available probiotic; 46 were treated with a placebo. Logistic regression was used to evaluate data. RESULTS: Salmonella organisms were detected in feces from 23 (9%) patients at least once during hospitalization. Patients were more likely to shed Salmonella organisms if diarrhea was evident < or = 6 hours after hospitalization and duration of hospitalization exceeded 8 days (odds ratio [OR], 20.3), laminitis developed during hospitalization (OR, 12.0), results of nasogastric intubation were abnormal (OR, 4.9), leukopenia was evident < or =6 hours after hospitalization (OR, 4.6), or travel time to the teaching hospital exceeded 1 hour (OR, 3.5). Horses treated with the probiotic did not differ from control horses in regard to likelihood of fecal Salmonella shedding (OR, 1.5) or prevalence of clinical signs. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that certain risk factors are associated with fecal shedding of S enterica among equine patients hospitalized at a veterinary teaching hospital because of colic and that pathogen monitoring in patients and the hospital environment and use of barrier nursing precautions for equine colic patients are beneficial.     

微生态制剂对断奶仔猪生长性能、器官重及其胃肠道发育的影响

通过给苏淮断奶仔猪饲喂微生态制剂(植物乳杆菌为主)研究其对断奶仔猪生长性能、器官重及其胃肠道发育的影响,分析仔猪生长性能与器官重、小肠形态、肠道pH的相关性,探讨微生态制剂缓解仔猪断奶应激的可能机制。选取健康、胎次和体重相近[(9.34±0.33)kg]的144头28日龄苏淮断奶仔猪,随机分为对照组(基础日粮)、抗生素组(基础日粮+抗生素)、微生态制剂组(基础日粮+微生态制剂),每组6个重复,每个重复8头仔猪。预试期为3d,试验于32日龄开始,59日龄结束时屠宰采样。结果表明,与对照组相比,微生态制剂可显著提高断奶仔猪平均日增重(ADG)和平均日采食量(ADFI)(P0.05),降低料重比(F/G)和腹泻率(P0.05);显著提高(P0.05)断奶仔猪脾脏相对重量;显著增加断奶仔猪十二指肠绒毛高度(P0.05),显著降低十二指肠、空肠、回肠绒隐比(P0.05),十二指肠、空肠、回肠隐窝深度有下降趋势,但差异不显著(P0.05);显著降低(P0.05)断奶仔猪盲肠、结肠pH。与抗生素组相比,微生态制剂组对各指标无显著影响(P0.05)。相关性分析显示,ADG增加与肝脏相对重量增加显著相关(P0.05);ADFI增加与十二指肠和脾脏相对重量、回肠绒隐比增加显著相关(P0.05),与结肠和盲肠pH、回肠隐窝深度降低显著相关(P0.05);F/G降低与结肠相对重量增加呈显著相关(P0.05);腹泻率下降与十二指肠相对重、脾脏相对重量、十二指肠和空肠绒隐比增加呈显著相关(P0.05)。由此看出,微生态制剂可通过增加器官重,改善肠道形态,降低胃肠道pH,提高断奶仔猪生长性能、降低腹泻率,缓解断奶应激对仔猪的影响,该微生态制剂具有替代抗生素的潜力。     

Evaluation of tulathromycin in the treatment of pulmonary abscesses in foals

Tulathromycin is a new injectable macrolide antibiotic used for the treatment of pulmonary diseases of swine and cattle. In this study, 37 foals with sonographic evidence of lung abscesses were treated with tulathromycin (2.5mg/kg intramuscularly [IM] once weekly, group 1) and 33 foals (group 2) with a combination of azithromycin (10mg/kg per os [PO] once daily for the first seven days of therapy, thereafter every other day) and rifampin (10mg/kg PO twice daily). The bacterial aetiological agent was not determined. The foals were only mildly sick and the median number of pulmonary abscesses was 1.4 (group 1) and 1.6 (group 2). Thirty foals in each group were treated without modifying therapy protocols until all clinical signs of disease had subsided. Tulathromycin was administered for a mean of 53 days, and azithromycin/rifampin for 42 days. The following side effects were associated with tulathromycin (279 IM injections): self-limiting diarrhoea in 11 foals; elevated temperature in six foals, and swellings at the injection site in 12 foals. This study provides some evidence that tulathromycin is well tolerated and appears promising for the treatment of pulmonary abscesses in foals.     

The Effects of Ivermectin Given Postpartum on the Incidence and Severity of Foal Heat Diarrhea

Foal heat diarrhea (FHD) is a major factor in the management of foals between 2 and 3 wk of age. The objective of this on-farm study was to determine the efficacy of postpartum anthelmintic treatment of mares for reducing the incidence and/or the severity of FHD in foals caused by parasitic infestation. Twenty-four Quarter Horse mares and their foals were alternately assigned to a treated or non-treated group according to expected foaling date. Treatment consisted of oral administration of Zimectrin® (Farnam Companies, Inc., Phoenix, AZ) to the dam within 12 h post-foaling. From d l through 25, foals were weighed, and vital signs and severity or absence of diarrhea were recorded. Incidence scores of 0 to 3 were assigned to each foal based on severity of diarrhea: 0 = no affliction and 3 = severe, watery diarrhea. There was no difference in incidence scores because of treatment; however, there was a trend for foals from treated mares to experience more severe diarrhea with a shorter duration. There was no difference in BW gain related to treatment or nontreatment of mares. Postpartum administration of Zimectrin to mares did not significantly decrease the incidence or severity of diarrhea in foals. Additionally, it did not affect growth rate of foals. The trend for foals from treated mares to have a shorter duration of FHD may be beneficial to farm managers who spend time and money treating and cleaning foals.     

Evaluation of a Veterinary Glucometer for Use in Horses

Background: Glucose assessment and regulation are important factors in the treatment of hospitalized horses and foals. Hypothesis/Objectives: The purpose of this study was to compare glucose measurement by a veterinary glucometer, adjusted by code for use in horses and foals, to a reference chemistry analyzer. It was hypothesized that the veterinary glucometer and reference analyzer would yield similar results and that interpretation of glucose values obtained from a veterinary glucometer would result in clinically appropriate decisions. Animals: Fifty blood samples from adult horses and 50 blood samples from neonatal foals admitted to the Colorado State University Veterinary Hospital or Equine Reproduction Laboratory for evaluation. Methods: Glucose concentrations from fresh whole blood samples were evaluated in duplicate with a veterinary glucometer and these values were compared with those obtained with a reference plasma chemistry analyzer. The accuracy of glucometer measurement was evaluated with a Clarke error grid. Results: The veterinary glucometer accurately measured whole blood glucose concentrations in both horses and foals when compared with a reference plasma chemistry analyzer. Nearly 97% of the glucometer values obtained in this study would have resulted in appropriate clinical decisions based on the Clarke error grid analysis. Conclusions and Clinical Importance: The veterinary glucometer evaluated has potential utility for point‐of‐care whole blood glucose evaluation in both horses and foals.     

Preliminary investigation of the probiotic potential of Lactobacillus rhamnosus strain GG in horses: fecal recovery following oral administration and safety

This study was designed to evaluate whether Lactobacillus rhamnosus strain GG (LGG), an extensively studied probiotic organism in humans, can colonize the intestines of adult horses and foals. Lactobacillus rhamnosus strain GG was administered to adult horses at doses of 1 x 10(9) CFU/50kg bodyweight (BW)/day (group 1, 7 horses), 1 x 10(10) colony forming units/ 50kg BW/day (group 2, 7 horses) and 5 x 10(10) colony forming units/50kg BW/day (group 3, 7 horses) for 5 d. Foals received 2 x 10(10) colony forming units/50kg BW/day (group 1, 7 foals) or 1 x 10(11) colony forming units/50kg BW/day (group 2, 7 foals) for 5 d. Fecal levels of L. rhamnosus strain GG in adult horses were low and variable in the 2 lower dose groups. Even in the high dose group, colonization was relatively low. In contrast, more consistent intestinal colonization was present in foals, and colonization persisted for up to 9 d following cessation of administration. No adverse effects were observed in any animal. Clinical studies evaluating this probiotic are indicated in foals. The presence of this organism in the feces of adult horses may only represent passive movement through the intestinal tract, not actual colonization. Consistent intestinal colonization in adults was only achieved with a prohibitively high dose.     

Effect of the probiotic Enterococcus faecium SF68 on presence of diarrhea in cats and dogs housed in an animal shelter

Background: Beneficial effects of probiotics have never been analyzed in an animal shelter. Hypothesis: Dogs and cats housed in an animal shelter and administered a probiotic are less likely to have diarrhea of ≥2 days duration than untreated controls. Animals: Two hundred and seventeen cats and 182 dogs. Methods: Double blinded and placebo controlled. Shelter dogs and cats were housed in 2 separate rooms for each species. For 4 weeks, animals in 1 room for each species was fed Enterococcus faecium SF68 while animals in the other room were fed a placebo. After a 1‐week washout period, the treatments by room were switched and the study continued an additional 4 weeks. A standardized fecal score system was applied to feces from each animal every day by a blinded individual. Feces of animals with and without diarrhea were evaluated for enteric parasites. Data were analyzed by a generalized linear mixed model using a binomial distribution with treatment being a fixed effect and the room being a random effect. Results: The percentage of cats with diarrhea ≥2 days was significantly lower (P= .0297) in the probiotic group (7.4%) when compared with the placebo group (20.7%). Statistical differences between groups of dogs were not detected but diarrhea was uncommon in both groups of dogs during the study. Conclusion and Clinical Importance: Cats fed SF68 had fewer episodes of diarrhea of ≥2 days when compared with controls suggests the probiotic may have beneficial effects on the gastrointestinal tract.     

Measurement of plasma colloid osmotic pressure in neonatal foals under intensive care: comparison of direct and indirect methods and the association of COP with selected clinical and clinicopathologic variables

Objectives: To describe and compare admission colloid osmotic pressure (COP) measurement using both direct and indirect methods in neonatal foals under intensive care, and to evaluate for associations between COP and clinical/clinicopathologic parameters. Design: Prospective study. Setting: Intensive care unit at a veterinary medical teaching hospital. Animals: Twenty‐six critically ill neonatal foals were studied. A control group consisted of 9 clinically healthy neonatal foals. Interventions: Clinicopathologic data were collected at the time of admission. COP was measured directly using a colloid osmometer. Indirect COP was calculated using equations by both Landis–Pappenheimer (L–P) and Thomas and Brown. Measurements and main results: Measured admission COP values were 17.1±4.3 and 17.7±2.4 mmHg in critically ill and control foals, respectively, and these values were not significantly different. Critically ill foals with blood lactate concentrations >3 mmol/L had lower COP values than those with lactate ≤3 mmol/L. There was close agreement between indirect COP values calculated using the L–P equation and direct COP values measured in control foals (mean error=0.0±1.3 mmHg; R²=0.87). However, indirect values were not as predictive of direct COP in critically ill foals (mean error=0.8±3.8 mmHg; R²=0.64). As COP values increased, the indirect method tended to overestimate COP, whereas at lower values it slightly underestimated COP. Conclusion: While the L–P equation was a close approximation of direct COP in healthy foals, direct measurements of oncotic pressure cannot be replaced for monitoring of critically ill foals. Critically ill foals with higher lactate concentrations had lower COP values, suggesting a possible relationship between COP and lactate.     

Bacteremia in equine neonatal diarrhea: a retrospective study (1990-2007)

Background: Bacteremia in sick foals is associated with survival, but the association of bacteremia and diarrhea is not reported.
Hypothesis: Neonatal foals with diarrhea will commonly be bacteremic.
Animals: One hundred and thirty-three neonatal foals.
Methods: Records of all foals <30 days of age presenting with diarrhea between January 1990 and September 2007 were reviewed.
Results: Sixty-six of 133 foals (50%) were bacteremic at admission, with 75 isolates from the 66 samples. The blood culture from a further 18 foals (13.5%) grew coryneform bacteria. Nine foals (6.8%) had 2 or more organisms grown on blood culture. One foal had 5 different organisms, interpreted as contamination. Forty-eight foals (36%) had no growth on admission blood cultures. No cultures isolated fungal organisms. Excluding coryneform bacteria, 43 isolates (57%) were Gram-negative organisms and 32 isolates (43%) were Gram-positive organisms. The most common isolate was Enterococcus spp. (22 isolates, 29%), followed by Pantoea agglomerans (13 isolates, 17%). IgG concentration at admission was not associated with blood culture status. Blood culture status was not associated with survival to hospital discharge.
Conclusions and Clinical Importance: Bacteremia is common in neonatal foals with diarrhea. Decisions regarding antimicrobial selection should be made with these differences in mind.     

Epidemiologic survey of diarrhea in foals

Epidemiologic and etiologic data about diarrhea in foals were collected under a planned prospective recording and monitoring study. The survey and monitoring procedures included a survey to obtain an overview of current horse management practices on participating farms, a daily health record survey to obtain information on mares and their foals, and collection of feces from 19 of 144 diarrheic foals and 10 age-matched nondiarrheic foals for electron microscopy, ELISA for rotavirus, and bacteriologic culture. Coronavirus was detected in the feces of diarrheic as well as clinically normal foals. Rotavirus was detected in the feces of diarrheic foals only. With regard to agents found in the feces, there was no significant (P less than 0.05) difference between diarrheic and nondiarrheic foals. Half of the 297 foals on which data were available developed diarrhea. Most foals that developed diarrhea lacked other clinical manifestations of disease. Basic cleanliness at foaling was associated with a lower percentage of foals developing diarrhea. Prophylactic use of antibiotics and vitamins in newborn foals was associated with a higher percentage of foals developing diarrhea. A higher percentage of foals born to visiting mares developed diarrhea, compared with foals born to resident mares.     

Retrospective comparison of azithromycin, clarithromycin, and erythromycin for the treatment of foals with Rhodococcus equi pneumonia

The objective of this retrospective study was to compare the efficacy of azithromycin-rifampin, clarithromycin-rifampin, and erythromycin-rifampin for the treatment of pneumonia caused by Rhodococcus equi in foals. Eighty-one foals with naturally acquired pneumonia caused by R. equi were included in the study. Information on age, sex, breed, physical examination findings, laboratory testing, and thoracic radiography was abstracted from each medical record. Foals were divided in 3 groups based on the antimicrobial agent selected for therapy. Short-term (discharge from the hospital) and long-term (apparently healthy as a yearling) success rates, days of hospitalization, days with fever, days with tachypnea, and percentage of radiographic improvement were compared among groups. Foals treated with clarithromycin-rifampin had significantly (P = .02) higher odds of overall short-term (odds ratio [OR] = 12.2) and long-term (OR = 20.6) treatment success and significantly fewer days with fever than foals treated with erythromycin-rifampin. Foals treated with clarithromycin-rifampin had a significantly (P = .03) higher percentage of radiographic improvement and a tendency (P = .06) toward higher odds of overall short-term (OR = 8.1) and long-term (OR = 11.8) treatment success compared to foals treated with azithromycin-rifampin. Among foals with severe radiographic lesions, the success rates of foals treated with clarithromycin-rifampin both short-term (88%) and long-term (83%) were significantly (P = .02) higher than that of foals treated with azithromycin-rifampin (0%). For each treatment group, the only reported adverse effect was diarrhea that was mild and self-limiting in most cases. The combination clarithromycin-rifampin is superior to azithromycin-rifampin or erythromycin-rifampin for the treatment of pneumonia caused by R. equi in foals in a referral population.