How effective is doramectin in treating swine parasitic diseases?
Doramectin is a new-generation macrolide antiparasitic drug. Compared with other commercially available ivermectin-class products, it has a broader antiparasitic spectrum, better efficacy, and a longer effective period for preventing parasite reinfection, making it currently the most effective and most development-worthy new veterinary antiparasitic drug in the world.
Doramectin is obtained by biosynthesis from a genetically engineered mutant strain of Streptomyces avermitilis after the addition of cyclohexylcarboxylic acid, and it has a cyclohexyl group at the C25 position. Doramectin is an endoparasiticide and ectoparasiticide combined, and is effective against both nematodes and arthropods.
The main parasites in large-scale pig farms in China include internal parasites such as Ascaris suum, Trichinella, Oesophagostomum, lungworms, kidney worms, and whipworms, and external parasites such as sarcoptic mange mites and blood-sucking lice. After infection by these parasites, pigs develop anemia, emaciation, and stunted growth and development, feed conversion rates decrease, and susceptibility to other diseases also increases, causing serious economic losses to the @#@227@#@ industry.
At present, the deworming drugs commonly used in China's pig industry include: (1) internal parasite drugs: albendazole, levamisole, trichlorfon, destomycin, hygromycin, ivermectin, abamectin; (2) external parasite drugs: trichlorfon, amitraz, diazinon, dichlorvos, pyrethroid drugs, abamectin, ivermectin. None of the above products alone can control both internal and external parasites at the same time. Generally speaking, two other products need to be used repeatedly multiple times to achieve a good deworming effect.
1. Therapeutic efficacy of doramectin
Doramectin has a good effect on swine gastrointestinal nematodes. For example, when pigs are given intramuscular injection at a dose of 0.3 mg/kg body weight, in both artificially infected and naturally infected cases, weight gain at 7 d, 14 d, and 21 d after administration is significantly higher than that of the control group (pig p<0.0001)；与对照组相比，虫体被100%驱除，同时没有副作用发生。
In the treatment of swine sarcoptic mange, it has a good effect from suckling piglets to sows. After artificial infection with sarcoptic mange mites, intramuscular injection at 0.3 mg/kg body weight was given, and after a 4-week trial, the results indicated that the effect on eliminating skin inflammation, lesions, and mite transmission among pigs was very obvious (p<0.05)。对怀孕母猪肾蠕虫的治疗中，0.3mg/kg的剂量颈部一次性注射，第56和57天检测时，尿虫卵的检出率为0，驱除率为100%，而对照组为每毫升尿液3762个卵。对猪肺蠕虫、消化道圆虫、猪虱等有同样的效果。
Based on the fact that a tissue drug concentration greater than 1 ng/ml(g) has antiparasitic activity, the effective duration of the drug can be evaluated:
The duration for which ivermectin remains at a concentration greater than 1 ng/ml(g) is: skin (18 d), lungs (18 d), gastrointestinal mucosa (18 d), abomasal mucosa (18 d).
The duration for which doramectin remains at a concentration greater than 1 ng/ml(g) is: skin (26 d), lungs (38 d), gastrointestinal mucosa (38 d), abomasal mucosa (38 d).
It can thus be seen that doramectin remains at greater than 1 ng/ml(g) in the gastrointestinal mucosa and lung tissue for 38 d, which is 20 d longer than ivermectin. Therefore, the parasite-killing effect of doramectin is significantly stronger than that of ivermectin, and its effective period for preventing parasite reinfection is also longer.
2. Methods of using doramectin to control parasitic infections in large-scale pig farms
1% doramectin injection, intramuscular injection, with a dosage of 0.3 mg/kg body weight, that is, 1 ml per 33 kg body weight. All pigs on the farm are dewormed once in spring and once in autumn each year. Sows: deworm once within 7-14 d before farrowing. First-parity sows: deworm once within 4-14 d before mating, and deworm once again within 7-14 d before farrowing. Breeding boars: generally deworm once in spring and once in autumn. Piglets: deworm once at 20-30 days of age (during the period of creep feeding for suckling pigs) and once at 60-70 days of age (before piglet transfer between groups). All newly introduced pigs should be treated once as a whole group, and after 10 d they can be mixed with other pigs.
Precautions: (1) Within one week of treatment, contact between untreated pigs and treated pigs should be avoided. (2) Deworming of sows should preferably be carried out during the non-pregnant period. (3) After medication, the environment must be thoroughly cleaned, and disinfection and insect control should be carried out at the same time.