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SUMMARY

A matched case-control study design was used to assess the effects of long-term administration of a prolonged release formulation of bovine somatotropin (sometribove) on clinical lameness and limb lesions in dairy cows. Cows treated with sometribove for at least 2 lactations (cases) and nontreated dairy cows matched by herd, parity, age, and stage of lactation (controls) in 8 herds were evaluated for clinical lameness (as assessed by gait abnormality) and limb lesions by 2 observers, using a standardized scoring procedure at a single herd visit. Although a high proportion of the study cows were clinically lame (43%), an association was not detected between chronic administration of sometribove and prevalent lameness. Of 21 types of limb lesions identified, 2 were positively associated and 2 were negatively associated with long-term sometribove use. Superficial laceration of the tarsus (odds ratio [or] = 2.1) and superficial swelling of the metatarsophalangeal joint (or = 4.5) were positively associated with sometribove treatment, whereas femoral lesions (or = 0.2) and superficial lacerations of the femur (or = 0.14) were negatively associated with sometribove treatment.

Free access
in American Journal of Veterinary Research

Summary:

An epidemiologic study investigating the prevalence of lameness in lactating dairy cows was performed in 17 dairy herds in Minnesota and Wisconsin. The mean herd size was 50 cows. Cows from 14 herds were housed in stanchions or tie stalls, and cows from 3 herds in free stalls or dry lot. During visits to each farm in the summer and subsequent spring, 2 investigators simultaneously but independently evaluated the ambulation of lactating cows by use of a standardized scoring system. The lameness scoring system was reliable at the 2 visits, with 92.7 and 91.3% agreement between the 2 observers and κ coefficients of 0.60.

The prevalence of lameness detected by the investigators (“clinical” lameness) was 13.7% (117/853) in summer and 16.7% (134/801) in spring in lactating dairy cows. These prevalences were 2.5 times higher than those estimated by the herd managers. Parity was significantly (P ≤ 0.03) associated with lameness, with higher prevalence of clinical lameness found in cows of higher parity.

Free access
in Journal of the American Veterinary Medical Association

Summary

A case-control study was conducted to determine risk factors for fecal shedding of Escherichia coli O157:H7 ( eco) in dairy calves. Three herds previously found to lack calves that shed eco in their feces were selected for each herd previously found to have calves that shed eco. Fecal samples from 965 calves on 64 farms were tested for eco by microbial culture. Sample prevalence of eco in calves less than 8 weeks old was 1.4% and in calves 8 weeks or older was 4.8%. Calves were 3 times more likely to shed eco after weaning than before weaning. Shedding of eco was associated with grouping calves before weaning; feeding whole cottonseed was negatively associated with eco shedding. The change in results between testing periods illustrated that an individual herd's status cannot be defined by a single testing of a small sample of cattle.

Free access
in Journal of the American Veterinary Medical Association

SUMMARY

Results of an elisa, indirect fluorescent antibody (ifa) test, and immunoblot analysis (western blotting) for antibody to Borrelia burgdorferi in a sample of 216 lactating dairy cows were compared. The microscopic microtitration agglutination test for antibody to 6 serovars of Leptospira interrogans was also performed to evaluate possible cross-reactivity between B burgdorferi and L interrogans. Using western blotting as the standard test against which the elisa and ifa test were compared, the elisa had greater sensitivity (50% in summer and 38% in spring) with similar specificity (83 and 82%), compared with the ifa test (sensitivity, 6 and 5%; specificity, 90 and 83%). In addition, seropositivity to B burgdorferi, using the elisa, was not found to be associated with seropositivity to L interrogans serovars.

A matched case-control study evaluating the association between clinical lameness and antibody to B burgdorferi was performed in lactating dairy cows of 17 Minnesota and Wisconsin herds. Sera from case and control cows matched by herd, parity, and stage of lactation were evaluated, using an elisa for B burgdorferi antibody during 2 seasons. High B burgdorferi antibody values were associated with clinical lameness in dairy cows (P = 0.006 in summer and P = 0.04 in spring).

Free access
in American Journal of Veterinary Research

Abstract

Objective—To develop robust reference intervals for hematologic and serum biochemical variables by use of data derived from free-ranging bottlenose dolphins (Tursiops truncatus) and examine potential variation in distributions of clinicopathologic values related to sampling sites' geographic locations.

Animals—255 free-ranging bottlenose dolphins.

Procedures—Data from samples collected during multiple bottlenose dolphin capture-release projects conducted at 4 southeastern US coastal locations in 2000 through 2006 were combined to determine reference intervals for 52 clinicopathologic variables. A nonparametric bootstrap approach was applied to estimate 95th percentiles and associated 90% confidence intervals; the need for partitioning by length and sex classes was determined by testing for differences in estimated thresholds with a bootstrap method. When appropriate, quantile regression was used to determine continuous functions for 95th percentiles dependent on length. The proportion of out-of-range samples for all clinicopathologic measurements was examined for each geographic site, and multivariate ANOVA was applied to further explore variation in leukocyte subgroups.

Results—A need for partitioning by length and sex classes was indicated for many clinicopathologic variables. For each geographic site, few significant deviations from expected number of out-of-range samples were detected. Although mean leukocyte counts did not vary among sites, differences in the mean counts for leukocyte subgroups were identified.

Conclusions and Clinical Relevance—Although differences in the centrality of distributions for some variables were detected, the 95th percentiles estimated from the pooled data were robust and applicable across geographic sites. The derived reference intervals provide critical information for conducting bottlenose dolphin population health studies.

Full access
in American Journal of Veterinary Research

Summary

We characterized the clinicopathologic manifestations of experimentally induced endotoxin-induced mastitis. Responses to hypertonic fluid therapy also were assessed. Eight cows received 1 mg of endotoxin by intramammary infusion in the left forequarter. Four hours after endotoxin administration, cows received 0.9% NaCl, 5 ml/kg of body weight (n = 4) or 7.5% NaCl, 5 ml/kg (n = 4) IV. Endotoxin-infused cows had expanded plasma volume, hyponatremia, transient hyperchloremia and hypophosphatemia, increased serum glucose concentration, and decreased serum activities of liver- and muscle-specific enzymes. Calculated plasma volume increased at 6 hours in cows receiving hypertonic NaCl, and at 12, 24, and 48 hours after endotoxin infusion in both groups. Concurrent observations of decreased serum protein concentration, erythrocyte count, and hematocrit supported observations of increased plasma volume. Relative plasma volume was greater in cows receiving hypertonic NaCl (124.3%) than in cows receiving isotonic NaCl (106.6%) at 6 hours after endotoxin infusion. Cattle receiving hypertonic NaCl had increased voluntary water intake after iv fluid administration. Increased water consumption was not accompanied by increased body weight, indicating probable occurence of offsetting body water loss. Serum sodium concentration in cows receiving hypertonic NaCl was increased 2 hours after fluid administration, but the magnitude of the change was minimal (< 4 mmol/L) and transient, indicating rapid equilibration with either interstitial or intracellular spaces. Serum sodium concentration was decreased in cows receiving isotonic NaCl at 12, 24, and 48 hours after endotoxin administration, compared with concentration prior to endotoxin adminstration, indicating selective loss of sodium.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To describe antimicrobial susceptibility patterns in Campylobacter spp isolated from dairy cattle and farms managed organically and conventionally in the midwestern and northeastern United States.

Design—Longitudinal study.

Sample Population—128 farms.

Procedure—Samples and data were collected every 2 months from August 2000 to October 2001. Fecal samples were collected from calves and cows. Milk samples were obtained from the bulk tank and milk line filters. Environmental samples were obtained from a water source, feed bunks of lactating cows, and cattle housing areas. Campylobacter identification and antimicrobial susceptibility testing were performed at a central laboratory by use of microbroth dilution with 2 customized antimicrobial susceptibility panels.

Results—460 and 1,570 Campylobacter isolates were obtained from organic and conventional dairy farms, respectively. Most isolates from both farm types were susceptible to most antimicrobial agents tested, and antimicrobial susceptibility of conventional dairy isolates was decreased, compared with organic dairy isolates. Low proportions of isolates resistant to ampicillin (< 10%) and moderate proportions resistant (30% to 60%) to kanamycin, sulfamethoxazole, and tetracycline were observed on both farm types. The proportion of isolates resistant to tetracycline was higher for conventional than organic farms.

Conclusions and Clinical RelevanceCampylobacter isolates from dairy cattle and farms managed organically and conventionally had similar patterns of antimicrobial resistance; the proportion of resistant isolates was higher for conventional than organic farms.

Full access
in Journal of the American Veterinary Medical Association