I will preface this article by saying although I am not a veterinarian, I have done some research and consulted trained veterinarians before writing this piece along with being a rare breed poultry breeder for over 25 years. Feel free to do your own research to make your own executive choices on this controversial subject.
Many customers come in asking for Ivermectin as they have been advised to use this product by a friend, relative or poultry breeder. What many do not understand is that the product is not labelled for poultry use and therefore not researched as to the required dosages, effect on birds (some say it causes infertility in flocks) and long term issues in birds (i have seen "burnt skin" from overdose, long term infertility etc) and the big question is what you and your family are consuming through egg production as it has not been labelled as safe for poultry.
I know there is a lot of confusion about using Ivermectin for chickens and that’s because it would be used off-label, meaning that, although it is often referred to by poultry owners an effective when treating chickens it was not developed for them. There is no scientific data about how it might affect them differently than mammals, the best route of administration and withdrawal periods for eating eggs or meat. The important thing to note here, is that due to no actual scientific research being carried out for poultry use, there are no guidelines for egg consumption when using ivomectin in poultry.
Now, my personal option on this is that due to these companies being a multi billion dollar companies, the fact no scientific research being carried out on poultry use would indicate that there is a very good reason that it hasnt been done. If these companies could make additional money from a product, most would spend the money and label accordingly IF IT WAS SUITABLE FOR THAT PURPOSE. I relate this to being no different to Glyphosate and what we have learnt from that.
I have spoken to many veterinarians about correct dosages for chickens and when I mentioned 3 drops for a standard sized bird, was told that was too much. They could not give me the correct dosage because it would be used off label, but pointed me in the right direction to make the calculation myself. They also gave me some info about how it works.