Well interesting posts on here, I have two books. Long distance pigeon racing by John Clements and Pigeon health management by Dr Colin Walker. Success seems to be gained by treatment or not, cleaning or not, in equal messure. I treat and have total confidence I'll get 'em from where ever they go. 275 mile for young 'uns 500 mile for yearlings North or South up to 750 mile. I have one race left to have a crack at, Lerwick, with my south roaders. Lerwick aint new to me flown it 25 years ago but not with south roaders. Have scored from Tarbes and Perth with the same pigeon.
Slugmonkey. I have a hen here that carries a high amount of kanker she breeds winners and is related to my 750 miler. She has a high tolerance so no worries.
Is it not our aim like you say raise the immunity and lower the levels of pathogens.
The biggest problem for most on here is they like certain birds and don't have the confidence to push 'em.
If you treat or test, and you are confident they are right they have to go. No place for untried birds here. No favourites. The young 'uns stand on there own merrits, as I never look in my book to see what they are off till after racing.