Doramectin is a new generation of macrolide antiparasitic drug developed by American shuotang (formerly Pfizer) at the end of last century. It is a kind of avermectin antibiotic which is fermented by a new strain of Streptomyces avermitilis with Cyclohexanecarboxylate as precursor. It is considered to be one of the best antiparasitic drugs in avermectin family at present. Compared with other ivermectin products, doramectin has the characteristics of high blood concentration, slow elimination, long duration of efficacy, more extensive anti insect spectrum and no allergic reaction, so it can be used as a good alternative to ivermectin. Doramectin is a new type of avermectin antiparasitic drug. Its anthelmintic effect is similar to that of ivermectin. It can inhibit the transmission of nerve impulses between nerves and muscles, and make the worm paralyzed and die from the host. However, due to the high blood concentration of doramectin in the body, its elimination is slower (half-life of doramectin is 5.7 days, half-life of ivermectin is 4.2 days), Therefore, it is safe to use.