Accuracy and inter-rater agreement among practitioners using quick thoracic ultrasonography to diagnose calf pneumonia.

BACKGROUND: Thoracic ultrasonography (TUS) is a commonly used tool for on-farm detection of pneumonia in calves. Different scanning methods have been described, but the performance of novice practitioners after training has not been documented. METHODS: In this study, 38 practitioners performed quick TUS (qTUS) on 18-23 calves each. Pneumonia was defined as lung consolidation 1 cm or more in depth. Diagnostic parameters (accuracy [Acc], sensitivity [Se] and specificity [Sp]) were compared to those of an experienced operator. Cohen's kappa and Krippendorff's alpha (Kalpha) were determined. The potential effects of training and exam sessions on performance were evaluated. RESULTS: The average relative Se and Sp were 0.66 (standard deviation [SD] = 0.26; minimum [Min.]-Maximum [Max.] = 0-1) and 0.71 (SD = 0.19; Min.-Max. = 0.25-1), respectively. The average relative Acc was 0.73 (SD = 0.11; Min.-Max. = 0.52-0.96). Over all sessions, Cohen's kappa averaged 0.40 (SD = 0.24; Min.-Max. = 0.014-0.90) and Kalpha was 0.24 (95% confidence interval [CI]: 0.20-0.27), indicating 'fair' agreement. Calf age and housing influenced Se and Sp. Supervised practical training improved Se by 17.5% (95% CI: 0.01-0.34). LIMITATIONS: The separate effects of calf age and housing could not be determined. CONCLUSION: This study showed that qTUS, like any other clinical skill, has a learning curve, and variability in performance can be substantial. Adequate training and certification of one's skill are recommended to assure good diagnostic accuracy.

Associations of serostatus upon arrival with clinical respiratory disease, lung consolidation, and growth in veal calves.

Respiratory tract infections remain a major problem during calf rearing, especially among milk (formula)-fed veal. Preconditioning of calves through appropriate colostrum management and vaccination could be helpful to address this issue. The objective of this study was to investigate whether the presence of serum antibodies against major respiratory tract pathogens (bovine respiratory syncytial virus, parainfluenza 3 virus, bovine coronavirus, Mycoplasmopsis bovis, Histophilus somni, Pasteurella multocida, and Mannheimia haemolytica) and total serum IgG concentration in calves upon arrival at the veal facility were associated with the occurrence of clinical bovine respiratory disease (BRD) or lung consolidation in the first 3 wk, as assessed by both the Wisconsin BRD scorecard (based on 5 clinical signs: cough, rectal temperature, ear position, and nasal and ocular discharge) and by quick thoracic ultrasound scanning. Additionally, the association between calves' serostatus production parameters were explored. A prospective cohort study was conducted among 442 male dairy calves on a large veal calf facility in Belgium. Both clinical scoring and quick thoracic ultrasound scanning were performed on all calves at 4 key moments in the production cycle: arrival at the facility, initiation of first metaphylactic antimicrobial treatment at peak incidence of BRD (wk 1), end of the first metaphylactic treatment (short-term evaluation) and at wk 10 (long-term evaluation). Mixed effects logit regression models were fitted to quantify relationships. The outcomes of interest were clinical respiratory disease (Wisconsin BRD scorecard positive), lung consolidation (≥1 cm or ≥ 3 cm), average daily weight gain, and cold carcass weight. In the first week of production, incidence of lung consolidation (≥1 cm) quickly increased from 14.9% upon arrival to 43.0% at the peak of the BRD incidence, while clinical BRD increased from 3.6% to 16.1%. The main finding of this study was that calves who were seropositive for bovine respiratory syncytial virus and bovine coronavirus at arrival had reduced odds of developing lung consolidation at the peak of the outbreak, 0.58 odds ratio (95% CI: 0.38-0.89) and 0.37 odds ratio (95% CI: 0.20-0.69), respectively. No relationships between serum IgG concentration at arrival and the development of lung consolidations or clinical respiratory disease were found. Nevertheless, on average, throughout the first 10 wk of the fattening cycle, calves with failed transfer of passive immunity (serum IgG < 7.5 g/L) gained 40 g/d (95% CI: 10-70 g/d) less weight (average daily gain). Hence, ensuring that calves have a positive serostatus for these respiratory tract pathogens before entering the facility may help lower the incidence of lung consolidations, subsequently reducing treatment incidence and the adverse effects on primary economic outcomes.

Effect of on-arrival bovine respiratory disease vaccination on ultrasound-confirmed pneumonia and production parameters in male dairy calves: A randomized clinical trial.

The high degree of commingling and accumulation of stressors during and after transport makes prevention of bovine respiratory disease (BRD) extremely challenging in the veal and dairy beef industry. Upon arrival, vaccination for agents involved in BRD is practically most achievable, but its efficacy under such conditions in dairy veal calves is unknown. Given the high prevalence of subclinical pneumonia in these settings, the primary objective of the present study was to determine the effect of 2 vaccination protocols administered upon arrival against bovine respiratory syncytial virus (BRSV), bovine parainfluenza type 3 virus (BPI-3), and Mannheimia haemolytica on clinical BRD and lung ultrasonographic findings in dairy veal calves. In addition, the effects of vaccination on average daily live weight gain and cold carcass weight were determined. In this randomized clinical trial, 443 male dairy calves were assigned to one of 3 groups: a negative, placebo-controlled group (n = 151), a vaccination group with 2 subcutaneous injections 4 wk apart with an inactivated vaccine containing BRSV, BPI-3, and M. haemolytica (parenteral [PE] group; n = 149) and a second vaccination group receiving an intranasal live-attenuated vaccine containing BRSV and BPI-3 and 2 subcutaneous vaccinations with the same inactivated vaccine as the PE vaccination group (intranasal-parenteral [IN-PE] group; n = 143). Clinical scoring and quick thoracic ultrasonography (qTUS) were performed on all calves on arrival (wk 0), at the peak of respiratory disease (outbreak; wk 1), at the end of the first antimicrobial group treatment (wk 3), and at a long-term evaluation point (wk 10). Culture and nanopore sequencing on nonendoscopic bronchoalveolar lavage (nBAL) samples were used to identify pathogens involved in the outbreak. Upon arrival, 15.1% of the calves had lung consolidation ≥1cm and incidence quickly rose to 42.8% during the outbreak. In both the PE and IN-PE group, the odds of pneumonia in wk 10 were reduced by 62% (odds ratio [OR] = 0.38; 95% confidence interval [CI] = 0.23-0.64) and 41% (OR = 0.59; 95% CI = 0.37-0.96), respectively. Short-term cure rate (50.3%), as determined immediately after the first group antimicrobial treatment, was not influenced by vaccination. In contrast, long-term cure rate, determined at wk 10, was affected by vaccination with higher cure in the PE group compared with the control group (69.4% vs. 51.2%; OR = 2.2; 95% CI = 1.1-5.0). Average daily gain in the first 10 wk of production was not affected by vaccination. Vaccination resulted in an increase in cold carcass weight of 3.5 and 4.3 kg in the PE (95% CI = -0.9-7.9) and IN-PE group (95% CI = -0.17-8.7), respectively. In conclusion, under the conditions of the present study, vaccination upon arrival resulted in a reduced prevalence of pneumonia at wk 10 of production, likely caused both by an improved cure rate of secondary infections and a reduced incidence of new cases between outbreak and long-term evaluation. The present protocol, using qTUS for pneumonia detection and nBAL diagnostics for pathogen identification adds a new dimension to randomized clinical trials on respiratory disease in calves.

Dynamics of subclinical pneumonia in male dairy calves in relation to antimicrobial therapy and production outcomes.

Quick thoracic ultrasonography (qTUS) is increasingly used as an on-farm method to diagnose clinical and subclinical pneumonia in dairy calves. The primary objective of this prospective cohort study was to describe dynamics of lung consolidation in a purchase-dependent production system for male dairy calves in relation to antimicrobial therapy and respiratory diagnostics. In addition, we studied the association of cured and uncured pneumonia with average daily gain (ADG) and cold carcass weight (CCW). The third objective was to determine the effects of arriving with lung consolidation on the probability of developing chronic unresponsive pneumonia and reduced performance. A total of 295 male dairy calves were intensively followed by qTUS and clinical scoring on 7 strategic occasions (wk 1, 2, 3, 4, 6, 8, and 12) during the production cycle. Of the calves, 17.6% (52/295) arrived with a lung consolidation ≥1 cm. At the first outbreak of respiratory disease (wk 1 after arrival), this incidence had risen to 30.8%. Initial therapy with tulathromycin and subsequently doxycycline appeared ineffective, resulting in a increase to 43.8% of calves having pneumonia in wk 4. At the start of the first outbreak (wk 1), the majority (86.8%) of the pneumonia cases were subclinical. At wk 4, the outbreak became more clinical, and treatment with amoxicillin resulted in a cure risk of 52.7%. Culture and nanopore sequencing diagnostics on nonendoscopic broncho-alveolar lavage (nBAL) samples identified bovine respiratory syncytial virus and Mycoplasma bovis as the dominant agents in the first outbreak. The isolated M. bovis strain showed mutations associated with macrolide resistance. The second outbreak was characterized by a Pasteurella multocida superinfection and isolation of multiple M. bovis strains from nBAL diagnostic testing. Evaluated over the complete observation period, 83.4% of the calves developed consolidations ≥1 cm on qTUS. Of these calves, 53.9% (135/246) were cured by antimicrobial therapy. Chronic pneumonia (≥30 subsequent days of pneumonia) was seen in 13.9% of the animals (n = 41). Calves with uncured or chronic pneumonia had a lower ADG (992 ± 174 g/d and 930 ± 146 g/d, respectively) compared with calves that never developed pneumonia (ADG = 1,103 ± 156 g/d). In contrast, calves that did fully cure trended toward a lower ADG than calves that never developed pneumonia, but differences were no longer significant. Also, the effect of uncured pneumonia was no longer significant for CCW. Calves with lung consolidation upon arrival had a lower ADG (981 ± 159 g/d vs. 1,045 ± 159 g/d) and were more likely to develop chronic pneumonia [odds ratio = 4.2; 95% confidence interval = 2.1-8.6] compared with calves without consolidation upon arrival. Animals with chronic pneumonia, in turn, had a lower CCW than animals without chronic pneumonia (10.3 ± 4.4 kg; 95% confidence interval: 1.6-19.1 kg). This study documents the consequences of subclinical pneumonia upon arrival and pneumonia developed later in the production cycle on production outcomes in a veal calf setting. Both qTUS and nBAL diagnostics provide important information, offering potential for better control and prevention of bovine respiratory disease in dairy calves.

Sepsis and survival in critically ill calves: Risk factors and antimicrobial use.

BACKGROUND: Sepsis is a life-threatening disease for which critically important antimicrobials (CIA) frequently are used. Diagnostic and therapeutic guidelines for sepsis and critically ill calves are largely lacking. OBJECTIVES: Identify factors associated with mortality in critically ill calves and describe bacteria obtained from blood cultures of critically ill calves with sepsis and their antimicrobial resistance. ANIMALS: Two-hundred thirty critically ill calves, mainly Belgian Blue beef cattle. METHODS: Retrospective cohort study. Logistic regression, survival analysis, and decision tree analysis were used to determine factors associated with mortality. RESULTS: Of the critically ill calves, 34.3% had sepsis and 61.3% died. The final survival model indicated that calves with sepsis (hazard risk [HR]: 1.6; 95% confidence interval [CI]: 1.0-2.5; P = .05), abnormal behavior (HR: 2.3; 95% CI: 1.3-4.0; P = .005), and hypothermia (HR: 0.82; 95% CI: 0.72-0.95; P = .01) had a significantly higher mortality risk. In a second survival model, hypothermia (HR: 0.87; 95% CI: 0.78-0.96; P = .004) and hypoglycemia (HR: 2.2; 95% CI: 1.5-3.3; P < .001) were risk factors for mortality. Decision tree analysis emphasized the importance of behavior, hypochloremia, hypoglycemia, hyperkalemia, and lung ultrasonography for mortality risk. Escherichia coli (30.6%) was most frequently isolated from blood cultures, of which 90.9% were multidrug resistant. Inappropriate use of antimicrobials was frequent for penicillin, amoxicillin, and sulfamethoxazole/trimethoprim, but less for CIA. CONCLUSIONS AND CLINICAL IMPORTANCE: Many critically ill calves have sepsis, which increases mortality risk. Bacteria involved are often resistant to first-intention antimicrobials but less resistant to CIA. The other identified risk factors for mortality can support therapeutic decision-making.

Cross-sectional study of primary antimicrobial treatment and vaccination coverage in outbreaks of bovine respiratory disease on dairy and beef farms in northern Belgium.

BACKGROUND: To what extent veterinarians active in the dairy or beef sector follow the antimicrobial therapy guidelines made available in different European countries for bovine respiratory disease (BRD) outbreaks, and whether differences in therapeutic or preventive preferences for BRD management exist, is currently unknown. Therefore, the objectives of this cross-sectional study were to compare vaccination coverage and primary antimicrobial and anti-inflammatory treatment on dairy, beef and mixed-breed farms in northern Belgium, and determine their compliance with the recommendations made by the Belgian formulary. METHODS: Information on antimicrobial and anti-inflammatory drug use and vaccination coverage from 190 BRD outbreaks in 180 herds, submitted by 101 veterinarians, was analysed. Multivariable linear probability models, adjusted for clustering at the veterinarian level, were used to determine differences between dairy and beef farms. RESULTS: Antimicrobials and non-steroidal anti-inflammatory drugs (NSAIDs) were used in 93.5% and 81.7% of the BRD outbreaks, respectively. First-line antimicrobials were used as primary treatment in only 42.3%, 50.9% and 38.6% of dairy, beef and mixed-breed farms, respectively. Significant differences (p < 0.05) were observed between dairy and beef farms in terms of use of long-acting macrolides (-17.2 percentage points [pp]; 95% confidence interval [CI]: -31.9, -2.5), steroidal anti-inflammatory drugs (15.2 pp; CI: 0.5, 29.8) and vaccination coverage (bovine respiratory syncytial virus, parainfluenza virus type 3 [33.1 pp; Cl: 15.7-50.6] and Mannheimia haemolytica [23.1 pp; Cl: 3.4-39.8]). LIMITATIONS: The herds that participated in this study were likely among the more motivated regarding BRD control. As such, the information on vaccination coverage is likely not entirely representative of herds in the study area. Interpretation is further complicated by the fact that vaccinated herds were potentially less likely to face a BRD outbreak and therefore participate in the current study. CONCLUSION: This study reveals differences in the primary use of (N)SAIDs, type of antimicrobials used and vaccination coverage on beef and dairy farms in the study region, and also differences in the appropriateness of antimicrobial selection based on the Belgian formulary.

Treatment protocols and management of retained fetal membranes in cattle by rural practitioners in Belgium.

Retained fetal membranes (RFM) is a frequent postpartum disorder in cattle causing considerable economic losses, and a common indication for antibiotic (AB) administration. There is controversy with regard to the treatment of RFM, and scientific recommendations are often in conflict with current legislation on AB use and practical routines in the field. The aim of this study was to assess the therapeutic approaches of RFM by Belgian rural veterinarians. A digital survey was sent to 468 Belgian veterinarians; 149 complete questionnaires (Wallonia: 78; Flanders: 71) were obtained. Survey questions captured socio-demographic characteristics, case definition, therapeutic approaches and treatment options for RFM. Questions on treatment were duplicated for dairy and beef cattle. When confronted with dairy cows suffering from RFM without fever, 35.6 % of vets do not treat with AB, while the majority administers AB, either intrauterine (47.6 %), systemically (10.7 %) or both (6.1 %). Dairy cows with RFM and fever receive a systemic (33.5 %), intrauterine (2.7 %) or combined (61.8 %) AB treatment. For a beef cow with RFM without fever, 21.5 % of vets prefer no AB treatment, while others prefer an intrauterine (24.2 %), systemic (24.8 %), combined (29.5 %) AB treatment. Beef cows with RFM and fever receive AB from the large majority of vets, by systemic (34.9 %) or combined (56.3 %) administration. In case of a parenteral treatment, benzylpenicillin, amoxicillin and ampicillin are by far the most frequently used molecules; only a minority of vets use cephalosporins. Manual placental removal is attempted by 93.9 % of the respondents. These results demonstrate that there is room for improvement when considering the treatment protocols of RFM. Many veterinarians use AB in RFM cows not presenting symptoms of general illness, or administer intrauterine AB in cows with or without clinical signs of illness. Concerning the molecules of choice, practical routines are largely in line with national AB recommendations. Beef cows suffering from RFM are treated more rigorously than dairy cows, regardless of their rectal temperature.