LUNG ULTRASONOGRAPHY AS A DIAGNOSTIC SCREENING TOOL AND POST-TREATMENT MONITORING WITH TULATHROMYCIN AND KETOPROFEN IN FATTENING BULLS AFFECTED BY BOVINE RESPIRATORY DISEASE (BRD)

The clinical presentation of the bovine respiratory disease (BRD) is commonly used for the diagnosis in-field. However, the non-specific manifestation frequently may lead to a misdiagnosis. These contexts represent the critical points in animal’s health management and economic losses. The aim of this study was to evaluate the thoracic ultrasonography (TUS) in the assessment of fattening bulls with BRD during the restocking period and the response to tulathromycin and ketoprofen treatment of animals with BRD over 21 days. Animal care and procedure were in accordance with the Guide for the Care and Use of Laboratory Animals and Directive 2010/63/EU for animal experiments. Sixty Limousine fattening bulls were enrolled in this study from a single beef-fattening herds located in Veneto, Italy. The fattening bulls received a clinical examination for body temperature, cough, nasal, and ocular discharges by veterinarian to establish the clinical respiratory score (RS) [1]. The TUS of six lung’s areas [caudal (10th–7th intercostal space (ICS)), middle (6th–5th ICS), and cranial (4th–3rd ICS) of both lung sides] was performed to establish the ultrasonography score (US)[2]. The lung lesions such as hepatizations areas and fluid alveolograms were measured for the six lung’s areas and to assess the total lung consolidation. The lesion score (LS) was calculated for each six lung areas by converting the lesion findings into a numeric scale. The global lesion score (GL) represents the total of the LS of each investigated lungs area. According to US the control group (Group C; 29 animals; US<3) and the disease group (Group D; 31 animals; US≥3) were established. The TUS assessments were performed at time 0 (T0; day of restocking and treatment for group D) and time 5 (T5; after 21 days) both in group C and group D. Moreover, group D was evaluated via TUS at time 1 (T1; after 1.5 days), time 2 (T2; after 3 days), time 3 (T3; after 7 days), and time 4 (T4; after 14 days). The differences between groups and over time were evaluated by mixed models with the significance set at p≤0.05. The RS, body temperature, nasal, and ocular discharges, GL, total hepatization, and total fluid alveolograms were greater in group D at T0, whereas only RS was greater at T5. The disagreement between TUS and RS, and the 40% of sick animals in group C based on RS suggest the inaccuracy of RS in the detection of BRD in beef fattening bulls. The most affected areas of the lungs were the cranial and middle lobes with greater hepatizations and fluid alveolograms areas. Furthermore, the difference in total hepatization between groups reduced from 8.05 cm2 at T0 to 2.50 cm2 at T5. The reduction in the size of the lesions is reasonably the consequence of recovery processes of the lung tissue, and the reduction of the inflammatory process response due to early antibiotic and anti-inflammatory administration with the resolution of acute pneumonia due to BRD. The treatment was effective in improve the US, and body temperature after 1.5 days, nasal, and ocular discharges after 14 and 3 days, respectively. The total hepatization showed an improvement after 1.5 days, whereas the GL and total fluid alveolograms improved after 3 days, suggesting a better health status of lungs with a resolution of acute lesions. This study confirms that TUS evaluation on the arrival of fattening bulls is a useful diagnostic tool for screening animals and to monitor the effectiveness of the treatment.