I have 7 Australorp hens, 4 EE hens, 6 Partridge Rock hens, 2 EE cockerels and 3 Autralorp/EE crosses that I keep in one coop. Tonight when shutting them in I noticed one Australorp hen had a pale comb (which I take as a sign of sickness) so I checked her out and sure enough she had some yellow poop/pus(?) on her vent. The vent itself did not look irritated nor is she bloated. The last time I saw this the hen became miserable and eventually died. I then checked my other hens and all of my Australorps (minus a broody one who wont leave the nest) seem to have vent problems. One hen is bloated with yellow poop/pus(?) on the vent and one has nothing on the vent, but the vent is blue! The others just have that same yellow poop/pus(?). All the other non-Australorp birds seem fine. I have noticed that the Australorps are not laying much at all recently. What the heck is this? Mass EYP? Are Australorps susceptible to some weird disease? Please help, I don't wish to have this spread to the rest of my flock!