Skip to main content


Table 1 In vivo efficacy of macrocyclic lactone products against Psoroptes ovis on 16 Belgian Blue beef farms in Belgium and the Netherlands

From: Resistance against macrocyclic lactones in Psoroptes ovis in cattle

FarmNo. of animalsAcaricideRedMC (%)95% CIResistance statusnTRMite-free proportion (%)
113IVM68.525.4–93.2Resistant> 70/13 (0)
210IVM99.397.7–100Sensitive48/10 (80)
39IVM /DOR33.3− 65.8 to 87.6Resistant32/9 (22)
47MOX-LA DOR7.6− 58.6 to 56.1Resistant> 40/7 (0)
59IVM− 36.8− 200.7 to 63.0Resistant> 50/7 (0)
69DOR97.892.4–99.0Sensitive24/9 (44)
79DOR78.572.2–83.9Resistant42/9 (22)
89IVM-82.5− 203.1 to 7.8Resistant52/9 (22)
910DOR97.894.0–99.7Sensitive35/10 (50)
109MOX89.765.4–99.5Resistant42/9 (22)
119DOR80.456.7–94.8Resistant23/9 (33)
129DOR95.886.2–99.8Suspected resistant41/9 (11)
138DOR50.329.7–67.8Resistant34/8 (50)
148DOR86.277.8–92.7Resistant35/8 (63)
1510DOR65.551.6–77.0Resistant22/10 (20)
169DOR92.082.6–97.8Resistant33/9 (33)
  1. Abbreviations: CI, confidence interval; IVM, ivermectin injectable (Ivomec 1%®); DOR, doramectin injectable (Dectomax®); MOX, moxidectin injectable (Cydectin®); LA, moxidectin injectable long-acting formulation; RedMC, average reduction in mite counts on a given farm after the first treatment round; nTR, number of treatment rounds until all animals at a given farm had a mite count of zero; mite-free proportion, the proportion of the animals with negative mite counts after the first treatment round