Use of Corid for chicken diarrhea or what?

[pacorona]

One of my hens, 2.5 yrs, is white and has now got a black behind. It seemed to be ok the other day, but it is black again and eggs have a bit of messy about them. I read to give Corid. Is this a good plan?

 

[azygous]

There are many causes of a messy vent, bacteria, fungus, mites being a few. Try adding probiotics to your chickens' diet. It may improve gut bacteria and curtail the messy poop. If your chicken isn't acting sick, it probably isn't coccidiosis causing the problem.

Inspect the vent closely for parasites, check the poop for worms, and look at the roosts after dark to see if mites may be present.

 

[aart]

One of my hens, 2.5 yrs, is white and has now got a black behind. It seemed to be ok the other day, but it is black again and eggs have a bit of messy about them. I read to give Corid. Is this a good plan?

@azygous has given good advice above.
I will add:
What all and how exactly are you feeding?

Where in this world are you located?
Climate is almost always a factor.
Please add your general geographical location to your profile.
It's easy to do, then it's always there!