Rhode Island Red hens dying suddenly

[nessie909]

I have several different breeds in my flock and all seem fine except my Rhode Island Red hens. I have lost 3 in less than a week. First we thought they were getting egg bound from their eggs shells being too hard and too big so I cut back on the oyster shell I had been giving them. Then we thought maybe the roosters, even though they typically all got along as they've all been together since they were babies. But we took two of the four roosters out and put them in separate cages and still lost another one. I am noticing blood in a nesting box and 2 of the 3 have bloody bottoms and look like their vents are wide open. I'm confused as to why this is only happening to this breed and what it even could be?

 

[ChickenCanoe]

There is no way to know for sure without lab work but when one loses multiple birds in short order it is definitely time to have a necropsy done.
Here is your state poultry lab. Send a freshly dead bird or a sickly one for euthanasia and necropsy.
Ohio

Animal Disease Diagnostic Laboratory
Ohio Department of Agriculture
8995 East Main St., Bldg. # 6
Reynoldsburg, Ohio 43068-3342
Phone: 614-728-6220
IAV-A, CSF, CWD*, ISA*, ND, FMD, PRV, SCRAPIE, IAV-S*, VHS*
Call them to see how they want the bird shipped.
How many hens do you have in that flock total?

Bloody stool can be a sign of coccidiosis but there are other things it could be. Some breeds/strains are more resistant or vulnerable than others.