Association between clinical respiratory signs, lung lesions detected by thoracic ultrasonography and growth performance in pre‐weaned dairy calves

Abstract

Background Bovine respiratory disease (BRD) is the main cause of mortality among 1-to-5 month old calves in Ireland, accounting for approximately one-third of deaths. Despite widespread use of clinical respiratory signs for diagnosing BRD, lung lesions are detected, using thoracic ultrasonography (TUS) or following post-mortem, in calves showing no clinical signs. This highlights the limitation of clinical respiratory signs as a method of detecting sub-clinical BRD. Using 53 purchased artificially-reared male dairy calves, the objectives of this study were to: (i) characterise the BRD incidence detected by clinical respiratory signs and/or TUS, (ii) investigate the association between clinical respiratory signs and lung lesions detected by TUS, and (iii) assess the effect of BRD on pre-weaning growth. Results Clinical BRD (based on Wisconsin clinical respiratory score and/or rectal temperature > 39.6 ºC) was detected in 43 % and sonographic changes (lung lesions) were detected in 64 % of calves from purchase (23 (SD; 6.2) days of age) until weaning, 53 days post-arrival. Calves with clinical BRD were treated. Sixty-one per cent calves affected with clinical BRD had lung lesions 10.5 days (median) before detection of clinical signs. Moderate correlations (rsp 0.70; P < 0.05) were found between cough and severe lung lesions on arrival day, and between rectal temperature > 39.6 ºC and lung lesions ≥ 2 cm2 on day 7 (rsp 0.40; P < 0.05) post-arrival. Mean average daily live weight gain (ADG) of calves from purchase to weaning was 0.75 (SD; 0.10) kg; calves with or without clinical BRD did not differ in ADG (P > 0.05), whereas ADG of those with severe lung lesions (lung lobe completely consolidated or pulmonary emphysema) was 0.12 kg/d less (P < 0.05) than calves without lung lesions. Conclusions Thoracic ultrasonography detected lung consolidation in calves that did not show signs of respiratory disease. The presence of severe lung lesions was associated with reduced pre-weaning growth. These findings emphasise the importance of using TUS in addition to clinical respiratory scoring of calves for an early and accurate detection of clinical and sub-clinical BRD.

Assessment of Rapid MinION Nanopore DNA Virus Meta-Genomics Using Calves Experimentally Infected with Bovine Herpes Virus-1

“…Bovine respiratory disease (BRD) is the leading cause of morbidity, mortality and economic loss in cattle of all ages [1][2][3][4][5]. The extensive use of vaccines against BRD-associated viral and bacterial pathogens has not reduced the incidence or severity of BRD in cattle.…”

“…A diagnosis of BRD is generally based on clinical signs that are assessed via visual inspection of the animal, measurement of rectal temperature and pulmonary auscultation [2,3,14,15]. If the identification of the causative pathogen(s) is attempted (which is often not the case), a nasal swab from the affected animal is sent to a diagnostic laboratory, where a targeted qPCR diagnostic analysis of only four or five of the most likely (e.g., previously mentioned) bacterial or viral pathogens is conducted [16,17].…”

Optimisation of rapid untargeted nanopore DNA virus metagenomics using cell cultures and calves experimentally infected with bovine herpes virus-1

“…Bovine respiratory disease (BRD) is the leading cause of morbidity, mortality and economic loss in cattle of all ages both in Ireland, and internationally [1][2][3][4][5] . The extensive use of vaccines against BRD-associated viral and bacterial pathogens has not reduced the incidence or severity of BRD in cattle.…”

“…A diagnosis of BRD is generally based on clinical signs which are assessed by visual inspection of the animal, measurement of the rectal temperature and pulmonary auscultation 2,3,14,15 . If identification of the causative pathogen/s is attempted (which is often not the case), a nasal swab from the affected animal is sent to a centralised laboratory where targeted qPCR diagnostics of only four or five of the most likely previously mentioned bacterial or viral pathogens is conducted 16,17 .…”

Показники Крові, Хворих На Бронхопневмонію Телят, За Умов Інтенсифікації Вільнорадикального Окиснення

“…Лікування тварин, хворих хронічною бронхопневмонією, до повного видужання не приводить, але допомагає припинити процес. Молодняк, що перехворів хронічною бронхопневмонією, не може бути використаний для племінних цілей і підлягає вибраковуванню [7][8][9]14].…”