Has anyone used this? My girl had this on Wednesday and this morning she had a drop or two of blood. Have spoken with the vet who says bring her back Monday if she hasn't dried up. Just wondered if this is normal? Could only speak to the receptionist and they weren't that clued up

Would never use this on a bitch that I wanted to breed from.  They either have their seasons (inconvenient as ti may be) or are spayed. 

It seems that it can cause detriment to the ability of the womb to form a good lining, and cystic ovaries.

My girl only seasons once a year and I took a litter last season. The breeding was planned as I wanted a boy for the ring. As I got the pup I wanted and that is the only reason I ever breed, then she was booked in for a spay at the end of April. She happened to throw a 7 month season unexpectedly and for personal reasons, her spay cannot be brought forward and there is no way that I will risk an unwanted pregnancy

In that case you will need to follow vets/manufacturers advise. 

The problem will be though determining the right time to get her spayed, so you may need to let her have another normal season, with the same issue of separation from males as you would have now, so I see no benefit, unless of course your going to be away or something.