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Abstract

Objective—To describe structural changes in the left atrioventricular (mitral) valve complex of dogs with endocardiosis by use of scanning electron microscopy.

Animals—5 clinically normal dogs and 4 dogs with mitral valve endocardiosis.

Procedure—The mitral valve complex from each dog was fixed and prepared for examination via scanning electron microscopy. Findings in valves from clinically normal and affected dogs were compared to identify surface changes associated with endocardiosis.

Results—Compared with findings in valves from clinically normal dogs, endocardiosis-affected mitral valve complexes had several morphologic abnormalities. Tissue swelling on the edge of valve leaflets, chordae tendineae, and the chordal-papillary muscle junction was evident. Damage to the valve complex endothelium was unevenly distributed; in some areas, denudation of endothelial cells had exposed the basement membrane or subendothelial valve collagen matrix. This damage was most noticeable on the leaflet edges and extended more to the ventricular aspect of the valve than the atrial side. Cell loss also extended to the chordae tendineae but was less apparent at the chordal-papillary muscle junction. The remaining endothelial cells on affected valves were arranged in less-ordered rows and had more plasmalemmal microappendages, compared with cells on unaffected valves.

Conclusions and Clinical Relevance—Morphologic changes associated with mitral valve endocardiosis in dogs were similar to those observed in humans with mitral valve prolapse. In dogs with mitral valve endocardiosis, gross changes in the valve complex may affect hemodynamics in the heart; alterations in the leaflet and chordal endothelium may contribute to pathogenesis of this disease. (Am J Vet Res 2004; 65:198–206)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To develop an early-warning automated surveillance-data–analysis system for early outbreak detection and reporting and to assess its performance on an abortion outbreak in mares in Kentucky.

Sample Population—426 data sets of abortions in mares in Kentucky during December 2000 to July 2001.

Procedures—A custom software system was developed to automatically extract and analyze data from a Laboratory Information Management System database. The software system was tested on data on abortions in mares in Kentucky reported between December 1, 2000, and July 31, 2001. The prospective space-time permutations scan statistic, proposed by Kulldorff, was used to detect and identify abortion outbreak signals.

Results—Results indicated that use of the system would have detected the abortion outbreak approximately 1 week earlier than traditional surveillance systems. However, the geographic scale of analysis was critical for highest sensitivity in outbreak detection. Use of the lower geographic scale of analysis (ie, postal [zip code]) enhanced earlier detection of significant clusters, compared with use of the higher geographic scale (ie, county).

Conclusions and Clinical Relevance—The automated surveillance-data–analysis system would be useful in early detection of endemic, emerging, and foreign animal disease outbreaks and might help in detection of a bioterrorist attack. Manual analyses of such a large number of data sets (ie, 426) with a computationally intensive algorithm would be impractical toward the goal of achieving near real-time surveillance. Use of this early-warning system would facilitate early interventions that should result in more positive health outcomes.

Full access
in American Journal of Veterinary Research

Summary

Concentration of sulfamethazine was measured in plasma and tissues (fat, liver, kidney, spleen, lungs, and skeletal muscle) of pigs given the drug iv and po. The plasma concentration vs time curve was best described by a 2-compartment model, with a distribution half-life of 0.46 hour and an elimination halflife of 16.9 hours. Bioavailability after oral administration was 85.8 ± 5.3%.

The tissue and plasma sulfamethazine concentration vs time data were used to develop a multicompartment pharmacokinetic model of sulfamethazine disposition in pigs. Plasma and tissue concentrations of sulfamethazine in pigs were measured at various intervals after multiple oral doses of sulfamethazine, and were compared to concentrations predicted by the model. Model predictions for tissue concentrations of sulfamethazine after addition of the drug to feed (110 μg/g of feed for 98 days; 550 μg/g for 30 days) were compared to results from other studies. The model accurately predicted the number of days for sulfamethazine concentration to fall below 0.1 μg of tissue/g (0.1 ppm, the tolerated concentration) in various tissues.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To determine whether airborne concentrations of virulent Rhodococcus equi at 2 horse breeding farms varied on the basis of location, time of day, and month.

Sample Population—2 farms in central Kentucky with recurrent R equi-induced pneumonia in foals.

Procedures—From February through July 2008, air samples were collected hourly for a 24-hour period each month from stalls and paddocks used to house mares and their foals. Concentrations of airborne virulent R equi were determined via a modified colony immunoblot technique. Differences were compared by use of zero-inflated negative binomial methods to determine effects of location, time, and month.

Results—Whether mares and foals were housed predominantly in stalls or paddocks significantly affected results for location of sample collection (stall vs paddock) by increasing airborne concentrations of virulent R equi at the site where horses were predominantly housed. Airborne concentrations of virulent R equi were significantly higher from 6:00 pm through 11:59 pm than for the period from midnight through 5:59 am. Airborne concentrations of virulent R equi did not differ significantly between farms or among months.

Conclusions and Clinical Relevance—Airborne concentrations of virulent R equi were significantly increased when horses were predominantly housed at the site for collection of air samples (ie, higher in stalls when horses were predominantly housed in stalls and higher in paddocks when horses were predominantly housed in paddocks). Concentrations of virulent R equi among air samples collected between the hours of 6:00 am and midnight appeared similar.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine whether the concentration of airborne virulent Rhodococcus equi varied by location (stall vs paddock) and month on horse farms.

Sample—Air samples from stalls and paddocks used to house mares and foals on 30 horse breeding farms in central Kentucky.

Procedures—Air samples from 1 stall and 1 paddock were obtained monthly from each farm from January through June 2009. Concentrations of airborne virulent R equi were determined via a modified colony immunoblot assay. Random-effects logistic regression was used to determine the association of the presence of airborne virulent R equi with location from which air samples were obtained and month during which samples were collected.

Results—Of 180 air samples, virulent R equi was identified in 49 (27%) and 13 (7%) obtained from stalls and paddocks, respectively. The OR of detecting virulent R equi in air samples from stalls versus paddocks was 5.2 (95% confidence interval, 2.1 to 13.1). Of 60 air samples, virulent R equi was identified in 25 (42%), 18 (30%), and 6 (10%) obtained from stalls during January and February, March and April, and May and June, respectively. The OR of detecting virulent R equi from stall air samples collected during May and June versus January and February was 0.22 (95% confidence interval, 0.08 to 0.63).

Conclusions and Clinical Relevance—Foals were more likely to be exposed to airborne virulent R equi when housed in stalls versus paddocks and earlier (January and February) versus later (May and June) during the foaling season.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine whether soil concentrations of total or virulent Rhodococcus equi differed among breeding farms with and without foals with pneumonia caused by R equi.

Sample Population—37 farms in central Kentucky.

Procedures—During January, March, and July 2006, the total concentration of R equi and concentration of virulent R equi were determined by use of quantitative bacteriologic culture and a colony immunoblot technique, respectively, in soil specimens obtained from farms. Differences in concentrations and proportion of virulent isolates within and among time points were compared among farms.

Results—Soil concentrations of total or virulent R equi did not vary among farms at any time point. Virulent R equi were identified in soil samples from all farms. Greater density of mares and foals was significantly associated with farms having foals with pneumonia attributable to R equi. Among farms with affected foals, there was a significant association of increased incidence of pneumonia attributable to R equi with an increase in the proportion of virulent bacteria between samples collected in March and July.

Conclusions and Clinical Relevance—Results indicated that virulent R equi were commonly recovered from soil of horse breeding farms in central Kentucky, regardless of the status of foals with pneumonia attributable to R equi on each farm. The incidence of foals with pneumonia attributable to R equi can be expected to be higher at farms with a greater density of mares and foals.

Full access
in American Journal of Veterinary Research