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Abstract

Objective—To estimate prevalence of cattle persistently infected (PI) with bovine viral diarrhea virus (BVDV) at arrival at a feedlot, prevalence of chronically ill and dead PI cattle, and the magnitude of excess disease attributable to a PI animal.

Design—Cross-sectional and cohort studies.

Animals—2,000 cattle at the time they arrived at a feedlot, 1,383 chronically ill cattle from 7 feedlots, and 1,585 dead cattle from a single feedlot.

Procedure—Skin biopsy specimens were collected and evaluated via immunohistochemistry. Cattle were characterized as either PI or not PI with BVDV on the basis of characteristic immunostaining. Follow-up was obtained for the 2,000 cattle from which samples were collected at arrival, and health outcomes were determined for cattle exposed and not exposed to a PI animal.

Results—Prevalence of PI cattle was 0.3% at arrival, 2.6% in chronically ill cattle, and 2.5% in dead cattle. Risk of initial treatment for respiratory tract disease was 43% greater in cattle exposed to a PI animal, compared with those not exposed to a PI animal. Overall, 15.9% of initial respiratory tract disease events were attributable to exposure to a PI animal.

Conclusions and Clinical Relevance—Relatively few PI cattle arrive at feedlots. However, those cattle are more likely to require treatment for respiratory tract disease and either become chronically ill or die than cattle that are not PI. In addition, they are associated with an increase in the incidence of respiratory tract disease of in-contact cattle. (J Am Vet Med Assoc 2005;226:595–601)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate viral and bacterial respiratory pathogens and Mycoplasma spp isolated from lung tissues of cattle with acute interstitial pneumonia (AIP) and cattle that had died as a result of other causes.

Sample Population—186 samples of lung tissues collected from cattle housed in 14 feedlots in the western United States.

Procedure—Lung tissues were collected during routine postmortem examination and submitted for histologic, microbiologic, and toxicologic examinations. Histologic diagnoses were categorized for AIP, bronchopneumonia (BP), control samples (no evidence of disease), and other disorders.

Results—Cattle affected with AIP had been in feedlots for a mean of 127.2 days before death, which was longer than cattle with BP and control cattle. Detection of a viral respiratory pathogen (eg, bovine respiratory syncytial virus [BRSV], bovine viral diarrhea virus, bovine herpesvirus 1, or parainfluenza virus 3) was not associated with histologic category of lung tissues. Bovine respiratory syncytial virus was detected in 8.3% of AIP samples and 24.0% of control samples. Histologic category was associated with isolation of an aerobic bacterial agent and Mycoplasma spp. Cattle with BP were at greatest risk for isolation of an aerobic bacterial agent and Mycoplasma spp.

Conclusion and Clinical Relevance—Analysis of these results suggests that AIP in feedlot cattle is not a consequence of infection with BRSV. The increased risk of isolation of an aerobic bacterial agent from cattle with AIP, compared with control cattle, may indicate a causal role or an opportunistic infection that follows development of AIP. (Am J Vet Res 2001; 62:1519–1524)

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in American Journal of Veterinary Research

Abstract

Objective—To describe time-dependent changes in plasma concentrations of 3-methylindole (3MI) and blood concentrations of 3-methyleneindolenine (3MEIN)-adduct in feedlot cattle.

Animals—64 yearling steers.

Procedures—Steers were assigned to 2 groups (32 steers/group). During the first 8 weeks, blood samples were collected from group 1 before the morning ration was fed, whereas samples from group 2 were collected 2 to 3 hours after the ration was fed. Blood samples were collected from all steers approximately 4 times/wk for 3 weeks and 3 times/wk for the subsequent 5 weeks. Samples were collected at the same time for all steers for an additional 10 weeks. Plasma samples were analyzed for 3MI concentrations. Blood samples collected from cattle in group 2 during the first 8 weeks were analyzed for 3MEINadduct concentrations.

Results—Mean blood concentration of 3MEINadduct increased to a maximum value on day 33 (0.80 U/μg of protein) and then decreased to a minimum on day 54 0.40 U/μg of protein). Plasma 3MI concentrations initially decreased and remained low until after day 54. Group-1 cattle had lower plasma 3MI concentrations, compared with concentrations for group-2 cattle. Blood 3MEIN-adduct concentrations and plasma 3MI concentrations were not associated with deleterious effects on weight gains.

Conclusions and Clinical Relevance—Blood 3MEIN-adduct concentrations peaked during the period of greatest risk for development of bovine respiratory disease complex. Conversely, plasma 3MI concentrations decreased during the same period. Animal-to-animal variation in metabolic capacity to convert 3MI to 3MEIN may be of more importance than differences in plasma 3MI concentration. Am J Vet Res (2002;63:591–597).

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in American Journal of Veterinary Research

Abstract

Objective—To evaluate the effect of feeding aspirin and supplemental vitamin E on growth performance, lung lesions, plasma concentrations of 3-methylindole (3MI), and 3-methyleneindolenine (3MEIN)-adduct concentrations in blood and pulmonary tissues of feedlot cattle.

Animals—256 crossbred steers; 64 cattle were used in experiment 1 and 192 cattle were used in experiment 2.

Procedures—A 2 × 2 factorial design was used for each experiment. Treatment factors were aspirin (0 or 3 g daily) and vitamin E (200 or 1,500 IU daily). Steers were housed in pens (8 steers/pen). Steers were slaughtered on days 59 and 138 for experiments 1 and 2, respectively. Lungs were grossly evaluated. Plasma 3MI concentration was determined, and 3MEIN-adduct concentrations were measured in blood and pulmonary tissues.

Results—Treatment was not associated with improvement or adverse effects on weight gain, drymatter intake, or feed efficiency in experiment 2. In experiment 1, 36 of 63 (57.1%) steers had lung lesions. Lesions were not associated with treatment or concentrations of 3MI and 3MEIN-adduct. Plasma 3MI concentration and concentrations of 3MEINadduct in blood and pulmonary tissues were 3.11 µg/mL, 0.51 U/µg of protein, and 0.49 U/µg of protein, respectively. Aspirin was associated with increased blood concentrations of 3MEIN-adduct for diets that did not contain supplemental vitamin E.

Conclusions and Clinical Relevance—Differences in performance of feedlot steers were not associated with treatment diet. It is possible that concurrent exposure of feedlot cattle to other factors typically associated with development of respiratory tract disease would affect these findings. (Am J Vet Res 2002:63:1641–1647)

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in American Journal of Veterinary Research

Abstract

Objective—To determine signalment, history, and clinical, necropsy, and microbiologic findings in dairy cows with hemorrhagic bowel syndrome.

Design—Retrospective study.

Animals—22 adult dairy cows from a single farm in Colorado.

Procedure—Medical records were reviewed for information on signalment, medical and reproductive history, the owner's chief complaints, results of physical examinations and ancillary diagnostic tests, treatment and response to treatment, results of microbiologic testing, and, if applicable, postmortem findings.

Results—Common clinical signs were acute signs of profound depression, decreased milk production, tachycardia, ruminal stasis, abdominal distention, and dark clotted blood in the feces. Rectal examination revealed distended loops of small intestine in 7 of 14 cows. Transabdominal ultrasonography revealed small intestinal ileus and distention in 12 of 12 cows and homogeneous echogenic intraluminal material compatible with intraluminal hemorrhage and clot formation in 4. Seven of 8 cows treated medically died; 9 of 13 cows that underwent surgery died or were euthanatized. Clostridium perfringens was isolated from fecal samples from 17 of 20 cows. The most common morphologic diagnosis at necropsy was severe necrohemorrhagic enteritis or jejunitis with intraluminal hemorrhage or blood clots. The most prominent histologic finding was severe, segmental submucosal hemorrhage and edema of the small intestine.

Conclusions and Clinical Relevance—Results confirm that in adult cattle, hemorrhagic bowel syndrome is a sporadic acute intestinal disorder characterized by intraluminal hemorrhage and obstruction of the small intestine. Clostridium perfringens was consistently isolated from the feces of affected cows. The prognosis for affected cows was grave. (J Am Vet Med Assoc 2002;221:686–689)

Restricted access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To test the hypothesis that feedlot cattle with acute interstitial pneumonia (AIP) have bacterial infection of the lung or liver and concurrent bovine respiratory syncytial virus (BRSV) infection significantly more often than pen mates without AIP.

Animals—39 feedlot cattle with signs consistent with AIP and no history of treatment with antimicrobials and 32 healthy control cattle from the same pens.

Procedure—Lung and liver specimens were obtained postmortem for bacterial or mycoplasmal culture and histologic examination; lung tissue was assessed for BRSV infection immunohistochemically.

Results—Among affected cattle, 26 had AIP confirmed histologically. Lung tissue from 11 cattle with AIP yielded microbial respiratory tract pathogens on culture; tissues from control animals yielded no microbial growth. In 4 cattle with AIP and 2 control animals, liver abscesses were detected; bacteria were isolated from abscessed tissue in 3 and 1 of those animals, respectively. Immunohistochemically, 9 cattle with AIP and no control animals were BRSV-positive. Histologically, 9 AIP-affected cattle had only acute alveolar damage with exudation, and the other 17 had acute exudation with type II pneumocyte hyperplasia. No lesions of AIP were detected in control animals. Only 4 AIP-affected cattle had bacterial infection of the lung with concurrent BRSV infection.

Conclusions and Clinical Relevance—Results indicated that microbial respiratory tract pathogens are more common in cattle with AIP than in healthy pen mates. Control of bacterial pneumonia late in the feeding period may reduce the incidence of AIP at feedlots where AIP is a problem. (Am J Vet Res 2004;65:1525–1532)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To compare concentrations of 3-methyleneindolenine (3MEIN) in lung tissues obtained from feedlot cattle that died as a result of acute interstitial pneumonia (AIP) and cattle that died as a result of other causes and to compare blood concentrations of 3MEIN in healthy feedlot cattle and feedlot cattle with AIP.

Study Population—Blood samples and lung tissues collected from 186 cattle housed in 14 feedlots in the western United States.

Procedure—Samples of lung tissues were collected during routine postmortem examination and submitted for histologic, microbiologic, and toxicologic examination. Blood samples were collected from cattle with clinical manifestations of AIP and healthy penmates. Histologic diagnoses were categorized as AIP, bronchopneumonia (BP), control samples, and other disorders. Concentrations of 3MEIN were determined in lung tissues and blood samples, using an ELISA.

Results—Concentrations of 3MEIN in lung tissues were significantly greater in AIP and BP samples, compared with control samples. Absorbance per microgram of protein did not differ between BP and AIP samples. Blood concentrations of 3MEIN were significantly greater in cattle with AIP, compared with healthy cattle or cattle with BP. Odds of an animal with AIP being a heifer was 3.1 times greater than the odds of that animal being a steer.

Conclusion and Clinical Relevance—Increased pulmonary production of 3MEIN may be an important etiologic factor in feedlot-associated AIP. (Am J Vet Res 2001;62:1525–1530)

Full access
in American Journal of Veterinary Research

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.

Restricted access
in Journal of the American Veterinary Medical Association