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  • Author or Editor: Lorin D. Warnick x
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in American Journal of Veterinary Research

Abstract

Objective—To determine whether, and at what time, penicillin enters milk at a concentration that is detectable following bulbar subconjunctival injection in lactating dairy cows.

Design—Randomized clinical trial.

Animals—66 Holstein cows that were at least 2 weeks past calving and had not been treated with antibiotics in the preceding 30 days.

Procedure—Cows were randomly assigned to receive a treatment of 1 ml (300,000 units) procaine penicillin G by bulbar subconjunctival injection or remain untreated. Composite milk samples were collected immediately before treatment and 4, 10, 16, 22, 28, and 40 hours after treatment. Milk samples were tested by use of a commercial test for β-lactam antibiotics.

Results—Among penicillin-treated cows, the first positive test results were observed 4 hours after treatment, and the last positive result was observed 22 hours after treatment. The percentages of positive test results before treatment and at 4, 10, 16, 22, 28, and 40 hours after treatment were 0, 9, 87, 42, 8, 0, and 0%, respectively. None of the untreated cows had positive test results for β-lactam antibiotics at any sampling time.

Conclusions and Clinical Relevance—Penicillin was detected in milk for up to 22 hours after a single subconjunctival injection of procaine penicillin G in cows. This result should be considered when recommending milk withholding periods following the administration of penicillin by this route in lactating dairy cows. (J Am Vet Med Assoc 2000;217:369–371)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To estimate the prevalence of fecal shedding of Salmonella spp among bovine patients at a veterinary teaching hospital, to identify risk factors for fecal shedding of Salmonella organisms, and to characterize the serotypes.

Design—Retrospective cohort study.

Sample Population—5,398 hospitalized cattle.

Procedures—Data were collected for all cattle admitted during an 11-year period. Fecal shedding of Salmonella spp was determined by means of standard bacteriologic culture. Multivariable logistic regression models were used to identify risk factors for shedding of Salmonella spp among patients.

Results—The prevalence of Salmonella shedding among clinical suspects was 6.5% (50/768), whereas that among nonsuspects tested through routine surveillance was 2.5% (50/2,020). Among clinical suspect calves, fecal shedding of Salmonella spp was more likely for those admitted in the fall (odds ratio [OR], 5.9), those with septicemia (OR, 3.3), or those with an umbilical hernia (OR, 8.6). Among clinical suspect adult cattle, those with enteritis (OR, 9.9) or metritis (OR, 5.2) were more likely to be shedding Salmonella spp. Among nonsuspect cattle, none of the variables were significant predictors of shedding status. Twenty-one serotypes were detected during the study period, with the most common being Salmonella enterica serotypes Typhimurium (33%), Newport (23%), and Agona (12%).

Conclusions and Clinical Relevance—Seasonal and disease risk factors for fecal shedding of Salmonella spp were evident among clinical suspect cattle admitted to a veterinary teaching hospital. In contrast, lack of significant associations among nonsuspect cattle would suggest that targeted screening within this population is not warranted.

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in Journal of the American Veterinary Medical Association

Objective

To determine whether a commercially available water hardness test kit could be used to measure total serum calcium concentration and diagnose hypocalcemia in dairy cows.

Design

Prospective study.

Animals

30 dairy cows from 19 commercial herds.

Procedure

Serum calcium concentration was determined using a water hardness test kit and a standard, laboratory-based method. Simple linear regression was used to determine whether there was a linear relationship between results of the 2 methods, and Spearman's rank correlation was used to calculate correlation between measurements. Sensitivity, specificity, and predictive values of using test kit-derived values for diagnosis of hypocalcemia (laboratory value < 8 mg/dl) were calculated.

Results

There was a high correlation and significant linear relationship between results of the 2 methods. Sensitivity, specificity, predictive value of a positive test result, and predictive value of a negative test result were 100, 73, 86, and 100%, respectively. Accuracy was improved by using a test kit-derived calcium concentration of 7 mg/dl as the cut-off for determining hypocalcemia.

Clinical Implications

Results indicate that a commercially available water hardness test kit can be used as a rapid, inexpensive method of estimating serum calcium concentrations and diagnosing hypocalcemia in dairy cattle. However, the test is not practical for cow-side use, because blood samples must be centrifuged to obtain serum for use in the test kit. (J Am Vet Med Assoc 1999;214:826–828)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine the phase and quantitate the electromyographic (EMG) activity of the genioglossus, geniohyoideus, hyoepiglotticus, omohyoideus, sternohyoideus, sternothyroideus, and thyrohyoideus muscles of clinically normal horses during strenuous exercise.

Animals—7 clinically normal adult horses (2 Thoroughbreds and 5 Standardbreds).

Procedures—Bipolar electrodes were surgically implanted in the aforementioned muscles, and horses were subjected to an incremental exercise test on a high-speed treadmill. The EMG, heart rate, respiratory rate, and static pharyngeal airway pressures were measured during exercise. The EMG was measured as mean electrical activity (MEA). The MEA values for maximal exercise intensity (13 or 14 m/s) were expressed as a percentage of the MEA measured at an exercise intensity of 6 m/s.

Results—MEA was detected during expiration in the genioglossus, geniohyoideus, sternohyoideus, and thyrohyoideus muscles and during inspiration in the hyoepiglotticus and sternothyroideus muscles. Intensity of the MEA increased significantly with exercise intensity in the genioglossus, geniohyoideus, and hyoepiglotticus muscles. Intensity of the MEA increased significantly in relation to expiratory pharyngeal pressure in the geniohyoideus and hyoepiglotticus muscles.

Conclusions and Clinical Relevance—Once exercise intensity reached 6 m/s, no quantifiable additional increase in muscular activity was detected in the omohyoideus, sternohyoideus, sternothyroideus, and thyrohyoideus muscles. However, muscles that may affect the diameter of the oropharynx (genioglossus and geniohyoideus muscles) or rima glottis (hyoepiglotticus muscle) had activity correlated with the intensity of exercise or expiratory pharyngeal pressures. Activity of the muscles affecting the geometry of the oropharynx may be important in the pathophysiologic processes associated with nasopharyngeal patency.

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in American Journal of Veterinary Research

Abstract

OBJECTIVE To describe the antimicrobial resistance patterns of Salmonella isolates obtained from horses in the northeastern United States and to identify trends in resistance to select antimicrobials over time.

SAMPLE 462 Salmonella isolates from horses.

PROCEDURES Retrospective data were collected for all Salmonella isolates obtained from equine specimens that were submitted to the Cornell University Animal Health Diagnostic Center between January 1, 2001, and December 31, 2013. Temporal trends in the prevalence of resistant Salmonella isolates were investigated for each of 13 antimicrobials by use of the Cochran-Armitage trend test.

RESULTS The prevalence of resistant isolates varied among antimicrobials and ranged from 0% (imipenem) to 51.5% (chloramphenicol). During the observation period, the prevalence of resistant isolates decreased significantly for amoxicillin—clavulanic acid, ampicillin, cefazolin, cefoxitin, ceftiofur, chloramphenicol, and tetracycline and remained negligible for amikacin and enrofloxacin. Of the 337 isolates for which the susceptibility to all 13 antimicrobials was determined, 138 (40.9%) were pansusceptible and 192 (57.0%) were multidrug resistant (resistant to ≥ 3 antimicrobial classes). The most common serovar isolated was Salmonella Newport, and although the annual prevalence of that serovar decreased significantly over time, that decrease had only a minimal effect on the observed antimicrobial resistance trends.

CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that current antimicrobial use in horses is not promoting the emergence and dissemination of antimicrobial-resistant Salmonella strains in the region served by the laboratory.

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in American Journal of Veterinary Research

Abstract

Objective—To evaluate the health and performance of young dairy calves vaccinated with a commercial Mannheimia haemolytica and Pasteurella multocida vaccine.

Design—Randomized clinical trial.

Animals—358 Holstein dairy calves between 14 and 20 days of age on 8 farms.

Procedure—Calves were randomly assigned to a control or vaccinated group. The vaccine used was a commercial modified-live M haemolytica and P multocida vaccine that was administered on days 0 and 14. Calf weight was measured on day 0 and monthly for 3 months. Farmers were asked to record any treatment given to the calves and the reason for treatment during the 4 months of the study. Blood was collected from all calves on days 0 and 28, and titers of antibodies to M haemolyticawere determined by means of direct bacterial agglutination.

Results—Mean daily gain was not significantly different between vaccinated and control calves. Vaccinated calves had a significantly greater increase in antibody titers (5.3-fold increase), compared with control calves (3.6-fold increase). There was no significant difference between vaccinated and control calves for any of the treatment outcomes (number and duration of treatments and age at first and last treatments).

Conclusions and Clinical Relevance—Results suggest that the M haemolytica and P multocidavaccine, given twice 2 weeks apart, was effective in increasing titers of antibodies against M haemolytica in young dairy calves but did not improve calf performance or health. (J Am Vet Med Assoc 2001;219:1739–1742)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine prevalence of udder cleft dermatitis in a dairy herd that was experiencing an outbreak of sarcoptic mange.

Design—Clinical survey.

Animals—1,597 Holstein cows and late-gestation heifers.

Procedure—Animals were examined for udder cleft dermatitis and for skin lesions consistent with sarcoptic or chorioptic mange. Skin scrapings were collected from 56 cows and examined for ectoparasites. The herd was revisited 1 year later, and prevalences of udder cleft dermatitis and lesions consistent with mange were determined in 506 cows.

Results—Of the 1,597 cattle examined, 280 (18%) had udder cleft dermatitis, and 1,397 (87.5%) had lesions consistent with mange. In 43 of 56 (77%) cows, skin scrapings revealed Sarcoptes mites. Udder cleft dermatitis was significantly more common in older than in younger cows. In first-lactation cows, udder cleft dermatitis was less common during the first 4 months of lactation than in the later stages of lactation, but udder cleft dermatitis was identified in cows in all stages of lactation and in cows that were not lactating. The herd was treated with eprinomectin to control mites, and prevalence of lesions consistent with mange 1 year later was only 2.8%. However, prevalence of udder cleft dermatitis was still 12%.

Conclusions and Clinical Relevance—Results suggest that cows in any stage of lactation and cows that are not lactating can have udder cleft dermatitis but that lesions are more common in older cows. Control of sarcoptic mange was accompanied by a moderate reduction in the prevalence of udder cleft dermatitis but did not eliminate the condition. (J Am Vet Med Assoc 2002;221:273–276)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To compare agreement between 2 pregnancy tests in dairy cattle.

Design—Evaluation study.

Animals—976 and 507 cattle for phases 1 and 2, respectively.

Procedures—Blood samples were collected, and palpation per rectum (PPR) was performed on cattle. Blood samples for the pregnancy-specific protein B (PSPB) ELISA were sent by courier to a commercial laboratory with results returned later. Results of PPR were extracted from herd records. Statistical comparison of results was performed by use of a mixed linear model and N analysis.

Results—Of 571 cattle classified as pregnant by the PSPB ELISA in phase 1, 30 (5%) were nonpregnant by PPR. Mean ± SE adjusted optical density (OD) of cattle classified pregnant by both tests was significantly higher (0.31 ± 0.01), compared with the adjusted OD of cattle classified pregnant by the PSPB ELISA and nonpregnant by PPR (0.22 ± 0.02). Of 255 cows classified pregnant by the PSPB ELISA in phase 2, 31 (12%) were nonpregnant by PPR. Mean ± SE adjusted OD of cattle classified pregnant by both tests was significantly higher (0.26 ± 0.01), compared with the adjusted OD of cattle classified pregnant by the PSPB ELISA and nonpregnant by PPR (0.21 ± 0.01). The N value was 0.82 and 0.81 for phases 1 and 2, respectively.

Conclusions and Clinical Relevance—Good agreement existed between the 2 tests, especially at longer intervals after insemination. Discrepant results appeared to be attributable to a nonviable fetus, embryonic loss, or fetal loss.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate effect of twin birth calvings on milk production, reproductive performance, and survival of lactating cows.

Design—Retrospective observational cohort study.

Animals—33,868 cows from 20 farms.

Procedures—Data on age at calving for primiparous cows and mature equivalent milk yield for multiparous cows, assistance at calving, stillbirths, twin births, gestation duration, pregnancy at the end of the data collection period, and culling-death for all cows were extracted from farm computer records and used for statistical analysis.

Results—Prevalence of twin parturitions was 1.3% (159/12,050) and 6.5% (1,410/21,818) for primiparous and multiparous cows, respectively. Primiparous and multiparous cows with singletons produced more milk than cows with live twins or at least 1 dead twin (primiparous, 33.1 vs 31.9 vs 31.2; multiparous, 36.5 vs 35.7 vs 35.0). Multiparous cows with dead twins produced less milk than cows with live twins. Compared with dams with singleton birth, cows with twins were 0.78 times as likely to conceive and 1.42 times as likely to die or be culled. Cows with dead twins also had increased time to conception, compared with live twins.

Conclusions and Clinical Relevance—Twin birth was associated with decreased survival, milk production, and reproductive performance. Having at least 1 dead twin was even more detrimental than having live twins and resulted in decreased milk production and reproductive performance of lactating cows.

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in Journal of the American Veterinary Medical Association