Abstract
BACKGROUND: In calves with diarrhea, it is critical to accurately determine the severity of dehydration and provide adequate fluid therapy. However, objective criteria are still limited. The aim of this study, a prospective cohort diagnostic study, is to compare caudal vena cava maximum diameter with expiration (CVCmax), caudal vena cava minimum diameter with inspiration (CVCmin), and caudal vena cava collapsibility index (CVC-CI) measurements before and after fluid therapy and to establish cut-off values for distinguishing between moderately and severely dehydrated calves. Twenty-four calves, with their degree of dehydration assessed based on enophthalmos and skin elasticity duration, were divided into two equal groups. Group I: consisted of 12 calves with an estimated degree of dehydration of 8-10% and were considered moderately dehydrated (degree of enophthalmos 4-6 mm, skin elasticity duration (s) 2-5). Group II: consisted of 12 calves with an estimated degree of dehydration 10-12% and were considered severely dehydrated (degree of enophthalmos 6-8 mm, skin elasticity duration (s) 5-10). Clinical examination, complete blood count and blood gas analysis, hemodynamic parameters (heart rate, respiratory rate, capillary refill time (CRT), L-lactate, systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP)) and ultrasonographic examinations were performed for 48 h: before treatment (hour 0), immediately after the first fluid bolus, and at hours 8, 24, and 48 after the first fluid bolus. The Friedman test was used for within-group comparisons over time, and the Mann-Whitney U test was used for between-group comparisons at different time points. Categorical data were analysed using the chi-squared test, and Fisher's exact test was used when expected cell counts were less than 5. Receiver operating characteristic (ROC) analysis was performed to determine the sensitivity, specificity, and cut-off (lower limit) of CVC diameter and CVC-CI (%) compared with selected parameters (SBP, DBP, MAP, and L-lactate) to discriminate between moderate and severe dehydration. Statistical significance was set at P < 0.05. RESULTS: CVCmax and CVCmin increased significantly after treatment in diarrheic calves (P < 0.05). Additionally, a significant decrease in CVC-CI (%) was observed in the treated diarrheic calves. Receiver operating characteristic (ROC) analysis showed that the area under the curve (AUC) of CVCmax was 0.885 (95% CI: 0.823-0.946; P < 0.001), with 82% sensitivity and 85% specificity at the intercept point of 1.05, the AUC of CVCmin was 0.913 (95% CI: 0.861-0.964; P < 0.001), with 89% sensitivity and 84% specificity at the intercept point of 0.66, and were the most reliable parameters in differentiating between moderate and severe dehydration. CONCLUSION: A significant increase in CVCmax and CVCmin diameters, along with a significant decrease in CVC-CI, was observed with fluid therapy. The CVCmax and CVCmin diameters can provide valuable information for distinguishing between moderately and severely dehydrated calves.