Search Results

Abstract

Objective—To evaluate effects of IV administration of penicillin G potassium (KPEN) or potassium chloride (KCl) on defecation and myoelectric activity of the cecum and pelvic flexure of horses.

Animals—5 healthy horses.

Procedure—Horses with 12 bipolar electrodes on the cecum and pelvic flexure received KPEN or KCl solution by IV bolus 4 hours apart. Each horse received the following: 2 × 10⁷ U of KPEN (high-dose KPEN) followed by 34 mEq of KCl (high-dose KCl), 1 × 10⁷ U of KPEN (low-dose KPEN) followed by 17 mEq of KCl (low-dose KCl), high-dose KCl followed by high-dose KPEN, and low-dose KCl followed by low-dose KPEN. Number of defecations and myoelectric activity were recorded for 60 minutes. The first three 5-minute segments and first four 15-minute segments of myoelectric activity were analyzed.

Results—Number of defecations during the first 15- minute segment was greater after high-dose KPEN treatment than after high-dose or low-dose KCl treatment. Compared with reference indexes, myoelectric activity was greater in the pelvic flexure for the first 5- minute segment after high-dose KCl treatment, in the cecum and pelvic flexure for the first 5-minute segment and in the pelvic flexure for the first 15-minute segment after low-dose KPEN treatment, and in the pelvic flexure for the first and second 5-minute segments and the first three 15-minute segments after high-dose KPEN treatment.

Conclusions and Clinical Relevance—IV administration of KPEN stimulates defecation and myoelectric activity of the cecum and pelvic flexure in horses. Effects of KPEN may be beneficial during episodes of ileus. (Am J Vet Res 2003;64:1360–1363)

Abstract

Objective—To evaluate a real-time quantitative polymerase chain reaction (QPCR) assay in the detection and quantitation of virulent Rhodococcus equi.

Sample Population—1 virulent, 2 intermediately virulent, and 2 avirulent strains of R equi and 16 isolates of bacteria genetically related to R equi.

Procedure—The QPCR assay was evaluated for detection and quantitation of the virulence-associated gene (vapA) of R equi in pure culture and in samples of tracheobronchial fluid, which were inoculated with known numbers of virulent R equi. Results were compared with those derived via quantitative microbial culture and standard polymerase chain reaction methods.

Results—The QPCR assay detected the vapAgene in pure culture of R equi and in tracheobronchial fluid samples that contained as few as 20 CFUs of virulent R equi/mL and accurately quantitated virulent R equi to 10³ CFUs/mL of fluid. The assay was highly specific for detection of the vapA gene of virulent R equi and was more sensitive than standard polymerase chain reaction for detection of R equi in tracheobronchial fluid.

Conclusions and Clinical Relevance—The QPCR assay appears to be a rapid and reliable method for detecting and quantitating virulent R equi. The accuracy of the QPCR assay is comparable to that of quantitative microbial culture. The increased sensitivity of the QPCR method in detection of virulent R equi should facilitate rapid and accurate diagnosis of R equi pneumonia in foals. (Am J Vet Res 2005;66:755–761)

Abstract

Objective—To determine the chemoprophylactic effect of gallium maltolate on the cumulative incidence of pneumonia caused by Rhodococcus equi infection in foals.

Animals—483 foals born and raised on 12 equine breeding farms with a history of endemic R equi infections.

Procedures—Group 1 foals were treated with a placebo and group 2 foals were treated with gallium maltolate (approx 30 mg/kg, PO, q 24 h) during the first 2 weeks after birth. Foals were monitored for development of pneumonia attributable to R equi infection and for adverse effects of gallium maltolate.

Results—There were no significant differences in the cumulative incidence of R equi pneumonia among the 2 groups.

Conclusions and Clinical Relevance—Chemoprophylaxis via gallium maltolate administered orally at approximately 30 mg/kg daily for the first 2 weeks after birth failed to reduce the cumulative incidence of pneumonia attributable to R equi infection among foals on breeding farms with endemic R equi infections. Further investigation is needed to identify strategies for control of R equi infections.

Abstract

Objective—To evaluate the correlation between halftime of liquid-phase gastric emptying (T₅₀), determined with nuclear scintigraphy using technetium Tc 99m pentetate, and absorption variables of orally administered acetaminophen.

Animals—6 mature horses.

Procedure—Technetium Tc 99m pentetate (10 mCi) and acetaminophen (20 mg/kg of body weight) were administered simultaneously in 200 ml of water. Serial left and right lateral images of the stomach region were obtained with a gamma camera, and T₅₀ determined separately for counts obtained from the left side, the right side and the geometric mean. Power exponential curves were used for estimation of T50 and modified R2 values for estimation of goodness of fit of the data. Serial serum samples were taken, and acetaminophen concentration was determined, using fluorescence polarization immunoassay. Maximum serum concentration (C_max), time to reach maximum serum concentration (T_max), area under the curve for 240 minutes and the absorption constant (K_a) were determined, using a parameter estimation program. Correlations were calculated, using the Spearman rank correlation coefficient.

Results—Correlations between T₅₀ and T_max and between T₅₀ and K_a were significant.

Conclusions and Clinical Relevance—T_max and K_a are valuable variables in the assessment of liquidphase gastric emptying using acetaminophen absorption. Acetaminophen absorption may be a valuable alternative to nuclear scintigraphy in the determination of gastric emptying rates in equine patients with normally functioning small intestine. (Am J Vet Res 2000;61:310–315)

Abstract

Objective—To evaluate the effect of erythromycin on motility of the ileum, cecum, and pelvic flexure of horses during the postoperative and post-recovery periods.

Animals—8 healthy adult horses.

Procedure—Horses were anesthetized and bipolar electrodes were implanted in smooth muscle of the ileum, cecum, and pelvic flexure. Approximately 4, 16, and 24 hours (postoperative recording sessions) and at least 8 days (post-recovery recording session) after surgery, myoelectric activity was recorded before and after administration of erythromycin (0.5 mg/kg).

Results—Following erythromycin administration, myoelectric activity was increased in the ileum during all postoperative recording sessions but not during the post-recovery recording session. Myoelectric activity was increased in the cecum following erythromycin administration only during the post-recovery recording session. Myoelectric activity was increased in the pelvic flexure following erythromycin administration during all recording sessions. During several recording sessions, there were short periods during which myoelectric activity was significantly decreased following erythromycin administration.

Conclusions and Clinical Relevance—Results suggest that erythromycin has an effect on myoelectric activity of the ileum, cecum, and pelvic flexure in horses; however, prokinetic effects of erythromycin administered during the postoperative period were not always the same as effects obtained when the drug was administered after horses had recovered from the effects of surgical implantation of recording devices. Therefore, caution must be exercised when extrapolating results of prokinetic studies in healthy animals to animals with abnormal gastrointestinal tract motility. (Am J Vet Res 2000;61:420–424)

Abstract

Objective—To determine the pharmacokinetics of gallium maltolate (GaM) after intragastric administration in adult horses.

Animals—6 adult horses.

Procedures—Feed was withheld for 12 hours prior to intragastric administration of GaM (20 mg/kg). A single dose of GaM was administered to each horse via a nasogastric tube (time 0). Blood samples were collected at various time points from 0 to 120 hours. Serum was used to determine gallium concentrations by use of inductively coupled plasma-mass spectroscopy. Noncompartmental and compartmental analyses of serum gallium concentrations were performed. Pharmacokinetic models were selected on the basis of the Akaike information criterion and visual analysis of plots of residuals.

Results—Serum concentration data for 1 horse were such that this horse was considered an outlier and excluded from noncompartmental and compartmental analyses. Noncompartmental analysis was used to determine individual pharmacokinetic parameters. A 1-compartment model with first-order input and output and lag time was selected as the best-fit model for the data and used to determine mean — SD values for maximum observed serum concentration (0.28 — 0.09 μg/mL), time of maximum concentration (3.09 — 0.43 hours), time to the first measurable concentration (0.26 — 0.11 hours), apparent elimination half-life (48.82 — 5.63 hours), area under the time-concentration curve (20.68 — 757 h—μg/mL), and apparent volume of distribution (73,493 — 18,899 mL/kg).

Conclusion and Clinical Relevance—Further studies are necessary to determine the bioavailability of GaM after intragastric administration in adult horses.

Abstract

Objective—To determine whether the concentrations of airborne virulent Rhodococcus equi in stalls housing foals during the first 2 weeks after birth are associated with subsequent development of R equi pneumonia in those foals.

Sample—Air samples collected from foaling stalls and holding pens in which foals were housed during the first 2 weeks after birth.

Procedures—At a breeding farm in Texas, air samples (500 L each) were collected (January through May 2011) from stalls and pens in which 121 foals were housed on day 1 and on days 4, 7, and 14 after birth. For each sample, the concentration of airborne virulent R equi was determined with an immunoblot technique. The association between development of pneumonia and airborne R equi concentration was evaluated via random-effects Poisson regression analysis.

Results—Some air samples were not available for analysis. Of the 471 air samples collected from stalls that housed 121 foals, 90 (19%) contained virulent R equi. Twenty-four of 121 (20%) foals developed R equi pneumonia. Concentrations of virulent R equi in air samples from stalls housing foals that developed R equi pneumonia were significantly higher than those in samples from stalls housing foals that did not develop pneumonia. Accounting for disease effects, air sample concentrations of virulent R equi did not differ significantly by day after birth or by month of birth.

Conclusions and Clinical Relevance—Exposure of foals to airborne virulent R equi during the first 2 weeks after birth was significantly (and likely causally) associated with development of R equi pneumonia.

Abstract

OBJECTIVE To compare bony changes of the third metacarpal bone (MC3) of Thoroughbred racehorse cadavers with (cases) or without (controls) catastrophic condylar fracture by use of standing MRI.

SAMPLE 140 forelimbs from 26 case horses (both forelimbs) and 88 control horses (single forelimb).

PROCEDURES Bone marrow lesions (BMLs), identified as a decrease in T1-weighted (T1W) signal and increases in T2*-weighted (T2*W) and short tau inversion recovery (STIR) signals, and dense bone volume percentage (DBVP), identified as decreases in T1W, T2*W, and STIR signals, in the distopalmar aspect of MC3 were recorded. Logistic regression was used to compare fractured and nonfractured limbs of cases and fractured limbs of cases with randomly selected limbs of controls.

RESULTS Among cases, fractured limbs were significantly more likely to have BMLs (26/26 [100%]) than were nonfractured limbs (7/26 [27%]). Fractured limbs of cases were significantly more likely to have BMLs (26/26 [100%]) than were limbs of controls (6/88 [7%]). Among cases, there was no significant difference in DBVP between fractured and nonfractured limbs in lateral (26% vs 21%, respectively) or medial (25% vs 20%, respectively) condyles. However, DBVP was significantly greater in fractured limbs of cases than in limbs of controls for lateral (26% vs 16%, respectively) and medial (25% vs 18%, respectively) condyles.

CONCLUSIONS AND CLINICAL RELEVANCE Standing MRI revealed a significantly greater degree of bone change in racehorses with condylar fracture when comparing fractured and nonfractured limbs of case horses and fractured limbs of case horses with randomly selected limbs of control horses.

Abstract

OBJECTIVE To determine the effects of oral omeprazole administration on the fecal and gastric microbiota of healthy adult horses.

ANIMALS 12 healthy adult research horses.

PROCEDURES Horses were randomly assigned to receive omeprazole paste (4 mg/kg, PO, q 24 h) or a sham (control) treatment (tap water [20 mL, PO, q 24 h]) for 28 days. Fecal and gastric fluid samples were collected prior to the first treatment (day 0), and on days 7, 28, 35, and 56. Sample DNA was extracted, and bacterial 16S rRNA gene sequences were amplified and sequenced to characterize α and β diversity and differential expression of the fecal and gastric microbiota. Data were analyzed by visual examination and by statistical methods.

RESULTS Composition and diversity of the fecal microbiota did not differ significantly between treatment groups or over time. Substantial variation in gastric fluid results within groups and over time precluded meaningful interpretation of the microbiota in those samples.

CONCLUSIONS AND CLINICAL RELEVANCE Results supported that omeprazole administration had no effect on fecal microbiota composition and diversity in this group of healthy adult horses. Small sample size limited power to detect a difference if one existed; however, qualitative graphic examination supported that any difference would likely have been small and of limited clinical importance. Adequate data to evaluate potential effects on the gastric microbiota were not obtained. Investigations are needed to determine the effects of omeprazole in horses with systemic disease or horses receiving other medical treatments.

Abstract

Objective—To determine the effects of treatment with platelet- and leukocyte-rich plasma (PRP) on future 2-, 3-, and 4-year-old racing performance of yearling Thoroughbreds with proximal sesamoid bone inflammation and associated suspensory ligament branch (SLB) desmitis.

Design—Randomized clinical trial.

Animals—39 yearling Thoroughbreds.

Procedures—Yearling Thoroughbreds with radiographic evidence of performance-limiting proximal sesamoid bone inflammation and ultrasonographic evidence of associated SLB desmitis were identified and randomly assigned to undergo PRP (treatment group) or saline (0.9% NaCl) solution (control group) injection at the affected SLB-proximal sesamoid bone junction. Race records of horses for the 2-, 3-, and 4-year-old racing years were obtained. Data regarding amount of money earned and number of races started were used as outcome measures, and results for groups were compared.

Results—Horses treated with PRP were significantly more likely to start at least 1 race during the 2-year-old racing year than were horses treated with saline solution; no significant differences were detected between groups regarding that variable for the 3- and 4-year-old racing years. No significant differences between groups were detected regarding earnings for any racing year.

Conclusions and Clinical Relevance—Although PRP-treated horses were more likely to start a race during the 2-year-old racing year versus control group horses, results for horses in each group were not significantly different for the 3- and 4-year-old racing years. Therefore, the PRP treatment protocol evaluated in this study did not seem to improve future racing performance of yearling Thoroughbreds with proximal sesamoid bone inflammation and associated SLB desmitis, compared with injection of saline solution.