my bitch was mated on the28 june 2nn of july noticed today she is losing a little dark red blood she is fine in herself and eating what do you think

I would still expect a bitch to finish her season after mating.  I assume it is just that blood you are talking about?

We have had many females still spotting after mating,

My bitch was mated on the 31st may and then the 2nd june, she had a few bloody spots come from her but then it went to a creamy colour, she was always licking her bits, i asked for advice on here and had loads of people come back to me, they told me to see a vet, which i did and the creamy colour was an infection a common one, so was treated with antibiotics. She is now 6 weeks and 2 days pregnant and doing well. But i would not worry about the dark colour but if it changes colour and your bitch is always licking her bits get her to the vets! Good luck!