Short communication: Diagnostic accuracy of focused lung ultrasonography as a rapid method for the diagnosis of respiratory disease in dairy calves.

This study estimates the accuracy of the focused lung ultrasound (FLUS) compared with systematic thoracic ultrasonography (TUS) as the reference test for diagnosing pneumonia in pre- and postweaned dairy calves. One hundred thirty-five Holstein Friesian calves, aged between 1 to 6 mo were enrolled and were kept in the same pen with one or more animals showing signs of bovine respiratory disease complex (BRDC). One operator performed FLUS on each calf, and then a second, blinded operator performed TUS on the same calf. For the FLUS, we only scanned the lung lobes that are most frequently affected during BRDC and are thus easier to detect, such as the caudal aspect of the cranial lobe of the left lung (fifth and fourth left intercostal spaces; ICS), the middle lobe of the right lung (fifth right ICS), and the caudal aspect of the cranial lobe of the right lung (fourth right ICS). Pneumonia was diagnosed when a calf had a minimum of one small lobular lung lesion that was at least 1 cm deep within a normally aerated lobe (TUS score of ≥2). Diagnostic accuracy indexes of the FLUS were calculated using TUS as the gold standard. The McNemar test was performed to evaluate the differences between the 2 techniques. In addition, an intertest agreement was assessed using the weighted kappa test. A total of 76 out of 135 calves had a TUS score of ≥2 and were therefore considered to be affected by BRDC. The FLUS had a sensitivity of 81.6% (95% CI = 71.0-89.5%), specificity = 100% (95% CI = 93.9-100%), positive predictive value was 100%, negative predictive value was 96.6% (95% CI = 94.7---97.9%), and accuracy was 97% (95% CI = 92.6-99.2%). The McNemar test highlighted a difference of 10.3% between the FLUS and TUS. The agreement between the TUS and FLUS was substantial (weighted kappa test 0.78). Although FLUS shows some limitations in diagnosing lung lesions associated with BRDC compared with the systematic approach, this study shows that the focused method could be used as an additional tool for evaluating consolidation, especially when examining a large number of postweaned dairy calves.

Plasma procalcitonin concentration in healthy calves and those with septic systemic inflammatory response syndrome.

The diagnosis of sepsis in calves is challenging. Blood culture and clinical signs combined with a complete blood count have been used for the diagnosis of sepsis. Recent literature in humans and animal species has been focused on sepsis-specific biomarkers, such as procalcitonin (PCT), that may more accurately and efficiently diagnose sepsis. The aim of this study was to evaluate plasma PCT concentrations in healthy and septic calves. Twenty healthy control calves and 58 sick calves with septic systemic inflammatory response syndrome (SIRS) based on SIRS score and clinical findings were included. Calves with septic SIRS were further divided in septic SIRS survivors (SSS) and non-survivors (SSNS). Plasma PCT concentrations were measured with a commercial ELISA assay for cattle. A receiver operating characteristic curve was used to determine cut-off values and corresponding sensitivity and specificity for the diagnosis of sepsis. Differences in plasma PCT concentration between groups (control vs. SSS vs. SSNS) were evaluated. Plasma PCT concentrations in healthy calves and those with septic SIRS were 33.3pg/mL (0-44.3pg/mL) and 166.5pg/mL (85.9-233.0pg/mL), respectively (P<0.001). The optimal cut-off value to predict septic SIRS was 67.39pg/mL (81.0% sensitivity, 95.0% specificity). Plasma PCT concentrations were 127.4pg/mL (72.2-216.0pg/mL) and 234.3pg/mL (204.5-309.4pg/mL) in the SSS and SSNS subgroups, respectively. Statistically significant differences were found among groups (control vs. SSS and SSNS, P<0.0001; SSS vs. SSNS, P>0.05). These results confirmed an increase in plasma PCT concentrations in calves with septic SIRS, as previously reported in humans and other species.

Risk factors associated with case fatality in 225 diarrhoeic calves: A retrospective study.

The aim of this retrospective study was to identify the major risk factors associated with case fatality in diarrhoeic calves undergoing a standard therapeutic protocol. Clinical and laboratory findings were reviewed in 225 Holstein Friesian diarrhoeic calves over a 2 year period. Calves were treated according to a fluid therapy protocol using an oral electrolyte solution or an IV infusion. After therapy, 159 calves were discharged in a healthy state, whereas 66 calves died. Logistic regression analysis showed that serum total protein (STP) concentration (odds ratio, OR, 0.51; 95% confidence interval, CI 0.31-0.84; P<0.01) and the strength of suckle reflex (OR 4.83; CI 1.17-19.88; P<0.05) were the major risk factors associated with case fatality in diarrhoeic calves. These results could help to distinguish between diarrhoeic calves with a good prognosis and those with a major risk of treatment failure.

Pharmacokinetics and sedative effects of dexmedetomidine in dairy calves.

AIMS: To evaluate the pharmacokinetics of dexmedetomidine (DEX) administered I/V at a dose of 5 µg/kg bodyweight in dairy calves and to compare the sedative effects of anaesthetic protocols involving DEX and xylazine. METHODS: Nine dairy calves, aged 17-20 days, were treated with 5 µg/kg I/V dexmedetomidine. For pharmacokinetic evaluation, blood samples were collected over 12 hours and serum samples were analysed by high performance liquid chromatography-mass spectrometry. Another nine dairy calves, aged 16-20 days, were treated with 0.2 mg/kg I/V xylazine. After both treatments, heart rate, respiratory rate and rectal temperature were measured for 20 minutes. Sedation quality and recovery times were also assessed. RESULTS: The kinetics of DEX was best described by a two-compartment model. The distribution and elimination half-lives were 8.7 (SD 5.0) and 83.5 (SD 67.5) minutes, respectively. Mean maximum concentration and body clearance were 12.5 (SD 8.6) ng/mL and 27.9 (SD 13.1) mL/minute/kg, respectively; the mean volume of distribution at steady state was 2,170.8 (SD 1,657.5) mL/kg. A decrease in heart rate was observed after treatments with both DEX and xylazine. No differences in heart or respiration rate, or rectal temperature were observed between the two treatment groups. The onset of sedation occurred after 2.7 (SD 0.67) minutes for calves treated with DEX and 2.8 (SD 0.78) minutes for calves treated with xylazine, and was characterised by a similar degree of deep sedation and ease of handling of the calves. All recoveries were eventless, and no adverse reactions were noted. CONCLUSIONS AND CLINICAL RELEVANCE: Dexmedetomidine treatment resulted in a reliable and long lasting sedation in calves, a transient decrease in heart rate and no modification in respiratory rate or rectal temperature. The results were comparable to xylazine, the most popular alpha-2-agonist among bovine practitioners. The use of DEX in dairy calves for rapid procedures such as dehorning or castration could be suggested.

Intravenous immunoglobulin transfusion in colostrum-deprived dairy calves.

Immunoglobulin transfusion is employed in the management of the failure of passive transfer (FPT). The aim of this study was to investigate the dose of immunoglobulin G (IgG) needed to reach a protective concentration (>10 g/L) in colostrum-deprived dairy calves. Twenty-eight Holstein Friesian newborn male calves were randomly assigned to either a control group (CG) or a treatment group (PG). Calves in the CG received 4 L of high quality colostrum within 12 h of birth. Calves in the PG received 62.7 ± 3.1 g of IgG IV in 2.6 ± 0.3 L of plasma within 6 h after birth. Serum immunoglobulin G (sIgG) and serum total protein (sTP) concentrations were assayed before and after (24 h, 72 h and 1 week after birth) plasma transfusion or colostrum ingestion. Serum (s) IgG and sTP concentrations increased in both groups throughout the period of observation. Mean sIgG and sTP concentrations after colostrum ingestion or plasma transfusion were higher in the CG than in the PG (P <0.01). Nine treated calves developed diarrhoea during the study and four were humanely euthanased due to progressive clinical deterioration. None of the calves in the CG showed signs of disease or died during the study. The dose of IgG used in this trial effectively provided an adequate sIgG concentration in colostrum-deprived calves (>10 g/L). Calves in the CG had significantly lower morbidity and mortality rates compared to those in the PG, suggesting that plasma transfusion alone is ineffective in providing complete protection against neonatal disease.