Practicability of somatic cell count and electrical conductivity as subclinical mastitis diagnostic tests in camels (Camelus dromedarius)

Critical gaps exist in our understanding of the diagnostic reliability of subclinical mastitis tests in dromedary camels. Using a retrospective longitudinal cross-sectional approach, 191 lactating camels were randomly sampled from 47 camel herds to investigate at first the practicability of somatic cell count (SCC) and electrical conductivity (EC) tests as subclinical mastitis tests in camels through their validations by California mastitis test (CMT) score, and then through the subsequent employments of those objective means in assessing certain potential risk markers predisposing camels to this disease. Results indicate the reliability and validity of SCC test, in contrast to EC test, in distinguishing subclinical mastitic udders in camels, as demonstrated by the strong interrelationships (r = 0.83 vs 0.12; R-2 = 0.80 vs 0.02), excellent agreement beyond chance (kappa coefficient = 0.76 vs 0.09) between SCC test and CMT scores, as well as by the high sensitivity of SCC test [Area Under Curve (AUC) = 0.94 vs 0.48] in distinguishing mastitic udders compared to the EC test. Based on the SCC test, the calculated overall prevalence rate for subclinical mastitis was 35 %, and the breed, parity, and lactation period were the only risk markers predisposing camels to subclinical mastitis. Collectively, it can be concluded that the objective SCC test possesses considerable diagnostic merit for early detection of subclinical mastitis in camels, while the EC test was non-satisfactory and non-diagnostic. Accordingly, it seems logical to base herd management decisions on SCC readings using the cut-off Log(10)SCC value of 5.67 (or SCC = 472.50 x 0(3) cells mL(-1)).