If its emaciated- they tend to fall over through being so weak :
Have you lot never had a bird come home, so weak, you don't know how it made it back - no breast muscles at all - just bones and feathers, s...ing through the eye of a needle unable to stand up
I have, one last year - and one today
If its a race bird it won't be PMV - because it will have been vaccinated, won't it? They have to be - or you can't race them