I have to say, of all the possible causes I mentioned above, it most sounds and looks like a possible case of peritonitis to me too, which is most commonly brought about by a broken egg inside the bird.
VERY prompt treatment with antibiotics and anti-inflammatories can sometimes help, but it's always pretty marginal whether they'll recover or not.
Really think a vet should see this hen asap.
VERY prompt treatment with antibiotics and anti-inflammatories can sometimes help, but it's always pretty marginal whether they'll recover or not.
Really think a vet should see this hen asap.