Having watched Youri Deblanc's videos again I am am very impressed. The bloke is not trying to 'big'himself up' as some sort of world authority, he is simply telling how he prepares his pigeons. And with his success, we might listen.
It got me thinking.
Youri Deblanc says he uses medications when he knows they have a disease.
Mark Gilbert treats his breeders and racers for canker, but will not treat his racers unless he has too.
Ad Schaerlaeckens always says that giving medications to pigeons routinely is a huge no no!
And this I know. When I was a jockey it was commonly accepted that if you had to give a racehorse penicillin for a chest infection or something, it would not win a race for at least 3 months afterwards. The antibiotics absolutely flattened them. These days there are other drugs, like Doxycycline and Trimethoprim, but they still come with a price.
A couple of weeks ago I had an abscessed tooth. Much pain and suffering

I ate some of my wife's Doxycycline and a great many pain killers and the dentist gave me another antibiotic to take in tandem. It all settled down, but the tooth will have to come out.
But the trade off was the antibiotics knocked hell out of me. I wasn't feeling all that good for a week or so.
And yet the notion that giving a racing pigeon a course of Doxycycline or ronidazole or similar will somehow make it healthier and therefore better still persists. I am convinced it will not. If a pigeon is fit and well and in form it will be about 100%.
You cannot make them be 110%