Detection of subclinical mastitis in camels (Camelus dromedarius) using somatic cell count, N-acetyl-β-D-glucosaminidase and lactate dehydrogenase activity

Abstract

Clinical and subclinical mastitis (SCM), mostly related to intramammary infection (IMI), is prevalent in pastoralist camel herds. An IMI has implications for public and animal health as well as for household economy. As bacterial culturing is expensive, time consuming and impractical in a pastoralist setting, other early detection methods for SCM in camels need to be investigated. Somatic cell count (SCC) is the standard for detecting SCM in cattle. The udder health indicators of N-acetyl-β-D-glucosaminidase (NAGase) and lactate dehydrogenase (LDH) activity are useful as diagnostic markers in cow, sheep and goat milk; they could be of potential use in camel milk production. The aim of this study was to improve the understanding of SCM in camels, and specifically to assess SCC, and NAGase- and LDH activity in camel milk. In addition, potential associations between SCM (defined by a California Mastitis Test (CMT) score ≥3 and no signs of clinical mastitis) and SCC, NAGase- and LDH activity were investigated. In total, 40 healthy camels without clinical mastitis were sampled in four herds in Kenya. Quarter milk samples were collected aseptically and screened using CMT. SCC was analysed using a direct cell counter (DCC, DeLaval), and NAGase and LDH activity was analysed using kinetic fluorometric measures. In total, 116 milk samples were tested with CMT and analysed for SCC. Of these, 88 were analysed further for NAGase and LDH. The median SCC was 151,000 cells/mL (IQR: 49,500–709,000 cells/mL), and median NAGase and LDH were 18.5 U/l (IQR:14.8–24.0 U/l) and 12.0 U/l (IQR: 8.5–16.2 U/l) respectively. All inflammatory markers (SCC, NAGase, LDH) were significantly associated with SCM (P < 0.001). In conclusion, SCC, NAGase and LDH are potential inflammatory indicators in camel milk that can be used for detection of udder quarters with SCM.