Two of my dogs are licking up their urine

My dogs Bonnie and Donna are licking up their urine, I was wondering what would make them do this, and how could I stop it? If anyone has any kind of help I would greatly appreciate it.

How old are the dogs?

This is sometimes a result of dogs beeing confined as a young pup, if they have only just started though then thats probably not the case. I have also heard that it can happen in unspayed females when their hormones change. It isnt harmful for them to drink their own urine as long as there is also clean water available to them. Have you changed anything in their diet or routine recently?