ABCD of deworming an animal effectively

Deworming by drenching is among farm health operations that farmers carry out on their own but one that can be fatal if not done the correct way.

Dear daktari,

I consulted a friend, also a farmer about deworming my cows. He told me that I can deworm them on my own. But he also confessed that he once lost his good animal while doing that. That scared me and I think I would rather call a vet to do it for me. What is your take on this?