I have two yorkies now, Reyna who is 1 yr 8 mo and Roxy the new baby who is 3 mo. I just discovered Roxy eating her own poop!!!!!!!!

ewwwww!!! Not only do I think is is absolutely disgusting but I am very concerned that she could pass on bacteria to Reyna via kisses, water bowl etc. causing an illness.
Is this a legitimate concern? Or will they both be fine? Will she grow out of this?
I could definitely use some advise....
Thanks so much!