
There is a condition called subinvolution of the placental sites, when the bitch will carry on bleeding right up to the next season - I had it once in a Kerry Blue of mine. Bit of a nuisance, but the male dogs seemed to know the difference, and didn't pester her. I suppose it could lead to a sort of anaemia if the bleeding is heavy.
Be best to check it out with your vet, however.
Jo and the Casblaidd Flatcoats