I cannot help you of course, but the fact that you are dealing with multiple bladder issues on different piggies sound me so strange. I guess there is something "wrong" in the diet...
Do your piggies eat fruits? or much vegs? vegs and fruits have an action on urine ph and bacteria need a certain ph for reproducing.
Do your piggies eat fresh grass? The piggies used to the grass (great amount) have usually less bladder issues (I have read a lot of vets reviews about this; a lot of grass, a lot of hay,few vegs and no fruits).
Anyway, as amother of a daughter who had serious bladder/kidney issues as a baby, I can say that yea, high proteins is not good and means that kidneys are not filtering in the proper way. But this can be only a temporary condition. Blood means a stone (no infection) or an infection (no stone); presence of nitrates, too, are important. Pain can be present or not...
Of course you need a vet, but I suggest you cranberry pure juice (diluited in water). I give it to my piggies, they love it and it might help.
Another thing: when a piggie is fighting over an infection here the best vets suggest to double the supplement of vit C reaching a dose of 40-50mg a day. We are adviced to use drops for humans, but usually vets make an injection. I have seen piggies recovering by themselves without important therapies. Vit C boosts immunitary system and also my daughter was given huge doses of vit C at the time of her nephritis (plus antibiotics of course). Cranberry juice is rich of vit C.
A herd with urinary issues is not normal... try to find out the possible cause
(cut off pellets and see if things improve)
