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Objective—To identify foal-related risk factors associated with development of Rhodococcus equi pneumonia among foals on farms with endemic R equi infection.
Design—Prospective case-control study.
Animals—220 foals at 2 equine breeding farms in Texas during a 2-year period.
Procedure—Information collected for each dam included age, time housed on the farm prior to parturition, whether there were any peripartum illnesses, parity, and health of previous foals. Information collected for each foal included breed, sex, gestational age, month and year of birth, location of birth, type of flooring and bedding in stall, postpartum management and preventive health care, passive immunity status, supplementation of immunoglobulins, exposure to other farms or foals affected with R equi pneumonia, stall and pasture exposure, commingling with other mare-foal pairs, age at weaning, and whether the foal developed R equi pneumonia.
Results—32 of the 220 (15%) foals developed R equi pneumonia, of which 4 (13%) died. Foals at 1 of the 2 farms and foals born during the second year of the study were more likely to develop R equi pneumonia. Foal-related factors that were examined were not significantly associated with risk of R equi pneumonia in multivariate analyses.
Conclusions and Clinical Relevance—Results suggest that there are farm- and year-related effects on the risk that foals will develop R equi pneumonia. Other foal-related factors significantly associated with R equi pneumonia were not identified. (J Am Vet Med Assoc 2003;223:1791–1799)
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.
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.
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.
Objective—To evaluate the correlation between the half-time of liquid-phase gastric emptying (T50) determined by use of nuclear scintigraphy, using technetium Tc 99m pentetate, and absorption variables of orally administered acetaminophen in horses with experimentally delayed gastric emptying.
Animals—6 mature horses.
Procedure—Delayed gastric emptying was induced by IV injection of atropine sulfate. Twenty minutes later, acetaminophen and technetium Tc 99m pentetate were administered simultaneously via nasogastric tube. Serial lateral images of the stomach region were obtained, using a gamma camera. 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 obtained, and acetaminophen concentration was determined, using fluorescence polarization immunoassay. Maximum serum concentration (Cmax), time to reach maximum serum concentration (Tmax), area under the curve for 480 minutes, and the appearance rate constant were determined, using a parameter estimation program. Correlations were calculated, using a Spearman rank correlation coefficient.
Results—A significant correlation was detected between T50 determined by use of scintigraphy and Tmax determined by use of acetaminophen absorption. Correlation between T50 and other absorption variables of acetaminophen was not significant.
Conclusions and Clinical Relevance—The acetaminophen absorption method was a valid technique in this model of delayed gastric emptying in horses. The method may be a valuable tool for use in research as well as in clinical evaluation of gastric emptying in horses. (Am J Vet Res 2002;63:170–174)
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)
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 (Cmax), time to reach maximum serum concentration (Tmax), area under the curve for 240 minutes and the absorption constant (Ka) were determined, using a parameter estimation program. Correlations were calculated, using the Spearman rank correlation coefficient.
Results—Correlations between T50 and Tmax and between T50 and Ka were significant.
Conclusions and Clinical Relevance—Tmax and Ka 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)
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)
Objective—To evaluate quality of duodenal tissue specimens obtained endoscopically from dogs and cats and submitted to 1 of 2 diagnostic laboratories for evaluation.
Sample Population—Slides from 50 consecutive canine and 50 consecutive feline endoscopically obtained duodenal tissue specimens submitted to laboratory 1 and 49 consecutive canine and 46 consecutive feline specimens submitted to laboratory 2.
Procedure—Slides were examined independently by 3 investigators, and each tissue piece on each slide was classified as clearly inadequate, questionable, or clearly adequate on the basis of 4 criteria. An overall score was then assigned to the slide.
Results—Slides from laboratory 1 were more likely to be scored as clearly adequate and less likely to be scored as clearly inadequate than slides from laboratory 2. Clearly adequate slides from laboratory 1 had a higher number of clearly adequate pieces of tissue than did clearly adequate slides from laboratory 2. Slides scored as clearly adequate had a higher number of individual tissue pieces than did slides scored as clearly inadequate.
Conclusions and Clinical Relevance—Results suggest that the quality of endoscopically obtained duodenal tissue specimens submitted to laboratories can vary, possibly because of differences in experience of individuals collecting biopsy specimens. Results suggest that at least 8 individual tissue pieces should be submitted when performing endoscopic biopsy of the duodenum in dogs and cats. (J Am Vet Med Assoc 2001;219:474–479)
Objective—To identify farm characteristics and management practices associated with development of Rhodococcus equi pneumonia in foals.
Design—Prospective case-control study.
Animals—5,230 foals on 138 breeding farms with 9,136 horses.
Procedure—During 2003, participating veterinarians provided data from 1 or 2 farms with ≥ 1 foal with R equi pneumonia and unaffected farms. Data from affected and unaffected farms were compared by use of logistic regression analysis.
Results—A number of variables relating to farm size and desirable management practices were significantly associated with increased odds of farms being affected with R equi pneumonia. By use of multivariate logistic regression, affected farms were determined significantly more likely to have raised Thoroughbreds, housed ≥ 15 foals, used concrete floors in foaling stalls, and tested foals for passive transfer of immunity than unaffected farms. These results remained significant even after accounting for exposure of foals to other breeding farms during the first month of life.
Conclusions and Clinical Relevance—Breeding farms with large acreage and a large number of mares and foals have greater odds of being affected by R equi pneumonia. Clinical relevance of associations with Thoroughbred breed and concrete flooring in foaling stalls remains uncertain. Desirable management factors commonly used on farms were not effective for controlling or preventing development of R equi pneumonia. This finding indicates a need to focus on host factors that influence disease development. (J Am Vet Med Assoc 2005;226:404–413)