[JaK]

None of my chickens have been vaccinated so I'm a bit worried...
A few friends have had trouble with myco and some of their hens have even died as a result despite treatment from the vet. I'm wondering if it's only a matter of time before my girls come down with it?
Can I vaccinate my girls against it?

[joyfull]

often birds are hatched with myco although it can remain dormant for a long time. It doesn't have to be a killer - just keep a very close eye on them and at the first sign of any respiratory infection then get them to a vets for a broad spectrum antibiotic. Nobody can say if it is myco until they have carried out a blood test.

[JaK]

Thanks, it's been bothering me that so many people seem to be dealing with it at the moment and have been wondering how it was spread. We have pigeons that roost in the trees above the chicken coop and often scratch around in the garden with the the chickens, it's just made me paranoid about it. 
Touch wood, I've not had any bother yet.

[joyfull]

it can be spread by wild birds but unless you keep them locked up all the time then this is a risk that you have to take. Are you absolutely sure the others had myco? did they go down the blood test route - they could have had another respiratory infection (of which there are several).

[Sassy]

Vaccinated birds can still come down with myco

[New shoot]

Its not inevitable you get problems JaK    I've had chickens for years and never had myco in the flock.

If you keep them clean, well-fed and healthy, that's half the battle.  If you have friends with chooks showing any signs of respiratory infection, I would say don't handle or go near the birds just as a precaution.  

Bird poop from wild birds can transmit worms, so if you have pigeons roosting above your coop, its worth roofing the coop or pruning back branches.  As Joyfull says, if you want to let them free-range, they will be in contact with wild birds and that is a risk you have to weigh up and decide whether you are OK with it or not  

[JaK]

Sadly it was myco that they had.

My Eglu is covered in pigeon poop, hence my worry but I think you have put me at ease. i have decided to scale things down again for next year because the weather has been so bad, keeping on top of the mud has been a huge battle.

I've had to stop mine from free ranging now but that's down to the mud that the flood left behind. The run we made is lightly raised with slabs on the ground so it's lovely and dry in there.