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in Journal of the American Veterinary Medical Association

Abstract

Objective

To isolate bovine coronaviruses from the respiratory tracts of feedlot cattle and compare antigenic and biological properties of these strains with bovine enteric coronaviruses.

Animals

5- to 8-month-old mixed-breed cattle at 4 feedlots.

Procedure

Samples were obtained from the nasal passages for testing. The 13 samples with the highest magnitude of positive values for bovine coronavirus (BCV) were cultured. Ten strains of bovine respiratory coronavirus (BRCV) were adapted successfully to serial passage. After observation of cytopathic effects (CPE) and confirmation of BRCV by immune electron microscopy and immunofluorescence testing, cell culture-adapted strains were cloned by limiting dilution. These isolates then were compared with a panel of bovine enteric coronaviruses (BECV), using hemagglutination (HA), receptor-destroying enzyme activity (RDE), hemagglutination inhibition (HI), and virus neutralization (VN) assays. Antigenic relatedness values then were calculated.

Results

The BRCV were detected in 105 of 488 (21.5%) of the cattle tested. Of 13 strains tested, 10 were isolated in cell culture. Six of the BRCV strains were similar to 2 strains obtained from neonatal calves with diarrhea and 2 strains from adult cattle with winter dysentery. The other 4 BRCV isolates had high RDE activity against mouse erythrocytes but differed from other strains of BECV. Nine of 10 BRCV isolates had properties similar to the 2 BECV subtypes.

Conclusions and Clinical Relevance

The BRCV can be isolated from nasal passages of cattle entering feedlots. Most BRCV were similar to BECV strains, although a few had unique properties. Vaccines developed to protect against enteric strains also may protect against respiratory tract strains. (Am J Vet Res 1999;60:1227–1233)

Free access
in American Journal of Veterinary Research

Abstract

Objective—To describe patterns of seroconversion to bovine coronavirus (BCV) and shedding of BCV from the respiratory tract in feedlot cattle.

Animals—1,074 calves in feedlots in Ohio, Texas, and Nebraska.

Procedure—Nasal swab specimens were obtained at time of arrival (day 0) and at various times during the initial 28 days after arrival at feedlots. Specimens were tested for BCV, using an antigen-capture ELISA. Serum samples were obtained at time of arrival and again 28 days after arrival; sera were analyzed for antibodies to BCV, using an antibody-detection ELISA.

Results—Samples from 12 groups of cattle entering 7 feedlots during a 3-year period revealed that 78 of 1,074 (7.3%) cattle were shedding BCV (range, 0 to 35.9% within specific groups). At time of arrival, 508 of 814 (62.4%) cattle had low (< 50) or undetectable BCV antibody titers. Seroconversion to BCV during the initial 28 days after arrival was detected in 473 of 814 (58%) cattle tested (range, 20.3 to 84.1% within specific groups). In cattle shedding BCV from the nasal passages, 49 of 68 (72.1%) seroconverted, and 472 of 746 (63.3%) cattle that were not shedding the virus seroconverted.

Conclusions and Clinical Relevance—Bovine coronavirus can be detected in populations of feedlot cattle in the form of viral shedding as well as seroconversion to the virus. Although only a few cattle were shedding the virus at the time of arrival at a feedlot, most of the cattle seroconverted to BCV by 28 days after arrival. (Am J Vet Res 2000;61:1057–1061)

Full access
in American Journal of Veterinary Research

Objective

To determine resting rectal temperatures of Vietnamese potbellied pigs.

Design

Prospective clinical trial.

Animals

85 potbellied pigs on a single farm and 27 potbellied pigs examined at a veterinary teaching hospital for routine veterinary care.

Procedure

Rectal temperatures of the potbellied pigs on a farm were measured during the morning, afternoon, and evening. Rectal temperatures at the time of initial examination were obtained from medical records for the potbellied pigs examined at the hospital.

Results

Mean rectal temperatures for both groups of potbellied pigs were the same. Overall unadjusted mean ± SD rectal temperature was 37.6 ± 0.8 C (99.7 ± 1.5 F; range, 35.1 to 39.6 C [95.2 to 103.3 F]). However, diurnal variation in rectal temperature was found among the farm population of potbellied pigs. After adjustment for age and repeated sampling, rectal temperatures recorded during the morning were found to be significantly lower than temperatures recorded during the afternoon and evening (mean difference, 0.5 and 0.9 C [0.9 and 1.6 F], respectively), and rectal temperatures recorded during the afternoon were found to be significantly lower than temperatures recorded during the evening (mean difference, 0.4 C [0.7 F]). There was a significant inverse linear relationship between age and rectal temperature.

Conclusions and Clinical Relevance

Rectal temperatures of Vietnamese potbellied pigs may be lower than the lower limit of the reference range reported for domestic pigs. Because of diurnal variation in rectal temperatures, it is important to compare temperatures obtained at the same time of day when assessing patients. (J Am Vet Med Assoc 1999;215:342–344)

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine the association between respiratory tract infection with bovine coronavirus (BCV), treatment for respiratory tract disease, pulmonary lesions at slaughter, and average daily gain in cattle in feedlots.

Animals—837 calves in feedlots in Ohio and Texas.

Procedure—Nasal swab specimens were obtained from cattle at arrival in a feedlot (day 0) and at various times during the initial 28 days after arrival. Specimens were tested for BCV, using an antigencapture ELISA. Serum samples were obtained at arrival and again 28 days after arrival and tested for antibodies to BCV, using an antibody-detection ELISA. Information was collected regarding treatment for cattle with respiratory tract disease and average daily gain during the feeding period. Pulmonary lesions were evaluated at slaughter.

Results—Cattle shedding BCV from the nasal cavity and developing an antibody response against BCV were 1.6 times more likely to require treatment for respiratory tract disease than cattle that did not shed the virus or develop an immune response against BCV. Additionally, cattle that shed BCV from the nasal cavity were 2.2 times more likely to have pulmonary lesions at slaughter than cattle that did not shed the virus. The BCV shedding or seroconversion status did not affect average daily gain.

Conclusions and Clinical Relevance—Bovine coronavirus infects feedlot cattle and is associated with an increased risk for cattle developing respiratory tract disease and pulmonary lesions. Development of appropriate control measures could help reduce the incidence of respiratory tract disease. (Am J Vet Res 2000;61:1062–1066)

Full access
in American Journal of Veterinary Research