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  • Author or Editor: D. David Lee x
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Abstract

Objective—To genetically type Campylobacter jejuni isolates from broiler houses or the external environment to identify the source of Campylobacter organisms in broiler chickens.

Sample Population—Environmental samples associated with broiler chickens, in commercial grow-out houses.

Procedure—Polymerase chain reaction (PCR) was used to amplify flaB, and the amplicon was digested with Sau3A to create a restriction fragment length polymorphism assay; PCR was also used to detect a transcribed spacer region in the 23S rRNA gene.

Results—Isolates possessing a 23S spacer region were more prevalent outside broiler houses than inside. Houses that had previously contained chickens or lacked biosecurity procedures were more likely to contain isolates possessing the 23S spacer. One house contained only isolates possessing the spacer, whereas an adjacent house contained only isolates lacking the spacer. The flaB type detected in broiler houses was different from the type detected in the environment; however, many isolates within the broiler houses contained untypable flaB genotypes.

Conclusions and Clinical Relevance—Most isolates from within houses were genetically distinct from isolates from outside houses that were examined by bacteriologic culture, suggesting an undetected source of C jejuni. Detection of isolates containing the 23S spacer appeared to be an indicator of environmental contamination of the houses. The observation of completely different C jejuni genetic types simultaneously within adjacent houses suggests that some types do not compete successfully during the grow-out period. In addition, the diversity of genotypes identified within broiler houses indicates the complexity of the ecologic features of C jejuni in the chicken environment. (Am J Vet Res 2001;62:190–194)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To compare pharmacokinetic and pharmacodynamic characteristics of fentanyl citrate after IV or transdermal administration in cats.

Animals—6 healthy adult cats with a mean weight of 3.78 kg.

Procedure—Each cat was given fentanyl IV (25 mg/cat; mean ± SD dosage, 7.19 ± 1.17 mg/kg of body weight) and via a transdermal patch (25 µg of fentanyl/h). Plasma concentrations of fentanyl were measured by use of radioimmunoassay. Pharmacokinetic analyses of plasma drug concentrations were conducted, using an automated curvestripping process followed by nonlinear, leastsquares regression. Transdermal delivery of drug was calculated by use of IV pharmacokinetic data.

Results—Plasma concentrations of fentanyl given IV decreased rapidly (mean elimination half-life, 2.35 ± 0.57 hours). Mean ± SEM calculated rate of transdermal delivery of fentanyl was 8.48 ± 1.7 mg/h (< 36% of the theoretical 25 mg/h). Median steadystate concentration of fentanyl 12 to 100 hours after application of the transdermal patch was 1.58 ng/ml. Plasma concentrations of fentanyl < 1.0 ng/ml were detected in 4 of 6 cats 12 hours after patch application, 5 of 6 cats 18 and 24 hours after application, and 6 of 6 cats 36 hours after application.

Conclusions and Clinical Relevance—In cats, transdermal administration provides sustained plasma concentrations of fentanyl citrate throughout a 5- day period. Variation of plasma drug concentrations with transdermal absorption for each cat was pronounced. Transdermal administration of fentanyl has potential for use in cats for long-term control of pain after surgery or chronic pain associated with cancer. (Am J Vet Res 2000;61:672–677)

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in American Journal of Veterinary Research

Abstract

Objective—To develop an in vitro model of cartilage injury in full-thickness equine cartilage specimens that can be used to simulate in vivo disease and evaluate treatment efficacy.

Sample—15 full-thickness cartilage explants from the trochlear ridges of the distal aspect of the femur from each of 6 adult horses that had died from reasons unrelated to the musculoskeletal system.

Procedures—To simulate injury, cartilage explants were subjected to single-impact uniaxial compression to 50%, 60%, 70%, or 80% strain at a rate of 100% strain/s. Other explants were left uninjured (control specimens). All specimens underwent a culture process for 28 days and were subsequently evaluated histologically for characteristics of injury and early stages of osteoarthritis, including articular surface damage, chondrocyte cell death, focal cell loss, chondrocyte cluster formation, and loss of the extracellular matrix molecules aggrecan and types I and II collagen.

Results—Compression to all degrees of strain induced some amount of pathological change typical of clinical osteoarthritis in horses; however, only compression to 60% strain induced significant changes morphologically and biochemically in the extracellular matrix.

Conclusions and Clinical Relevance—The threshold strain necessary to model injury in full-thickness cartilage specimens from the trochlear ridges of the distal femur of adult horses was 60% strain at a rate of 100% strain/s. This in vitro model should facilitate study of pathophysiologic changes and therapeutic interventions for osteoarthritis.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate effectiveness of 4% peroxymonosulfate disinfectant applied as a mist to surfaces in a large animal hospital as measured by recovery of Staphylococcus aureus and Salmonella enterica serovar Typhimurium.

Design—Field trial.

Sample Population—Polyester transparencies inoculated with bacteria.

Procedure—Polyester transparencies were inoculated with S aureus or S Typhimurium and placed in various locations in the hospital. After mist application of the peroxygen disinfectant, viable bacterial numbers were quantified and compared with growth from control transparencies to assess reduction in bacterial count.

Results—When applied as a mist directed at environmental surfaces contaminated with a geometric mean of 4.03 × 107 CFUs of S aureus (95% confidence interval [CI], 3.95 × 107 to 4.11 × 107) or 6.17 × 106 CFUs of S Typhimurium (95% CI, 5.55 × 106 to 6.86 × 106), 4% peroxymonosulfate reduced the geometric mean number of viable S aureus by 3.04 × 107 CFUs (95% CI, 8.6 × 105 to 1.7 × 106) and S Typhimurium by 3.97 × 106 CFUs (95% CI, 8.6 × 105 to 3.5 × 106).

Conclusions and Clinical Relevance—Environmental disinfection with directed mist application of a 4% peroxymonosulfate solution was successful in reducing counts of bacterial CFUs by > 99.9999%. Directed mist application with this peroxygen disinfectant as evaluated in this study appeared to be an effective and efficient means of environmental disinfection in a large animal veterinary hospital and would be less disruptive than more traditional approaches to intensive environmental cleaning and disinfection. (J Am Vet Med Assoc 2005;227:597–602)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To identify herd-level risk factors for bovine respiratory disease (BRD) in nursing beef calves.

Design—Population-based cross-sectional survey.

Sample—2,600 US cow-calf producers in 3 Eastern and 3 Plains states.

Procedures—The associations of herd characteristics with BRD detection in calves and cumulative BRD treatment incidence were determined.

Results—459 (177%) surveys were returned and met the inclusion criteria; 48% and 52% of these surveys were completed by producers in Plains and Eastern states, respectively. Mean (95% confidence interval) number of animals in herds in Plains and Eastern states were 102 (77 to 126) and 48 (40 to 56), respectively. Bovine respiratory disease had been detected in ≥ 1 calf in 21% of operations; ≥ 1 calf was treated for BRD and ≥ 1 calf died because of BRD in 89.2% and 46.4% of operations in which calf BRD was detected, respectively. Detection of BRD in calves was significantly associated with large herd size, detection of BRD in cows, and diarrhea in calves. Calving season length was associated with BRD in calves in Plains states but not Eastern states. Cumulative incidence of BRD treatment was negatively associated with large herd size and examination of cows to detect pregnancy and positively associated with calving during the winter, introduction of calves from an outside source, offering supplemental feed to calves, and use of an estrous cycle synchronization program for cows.

Conclusions and Clinical Relevance—Results of this study indicated factors associated with calf BRD risk; modification of these factors could potentially decrease the incidence of BRD in nursing calves.

Full access
in Journal of the American Veterinary Medical Association