I have a 3 year old bitch who had her first litter in May of this year - just two puppies. She had a lot of milk and her two boys did really well. She got mastitus and was put on a course of Synulox which seemed to sort it out.  About a week later, it came back so she was put back onto Synulox, but this time it didn't seem to be having any effect.  If you gently squeezed the infected teat a bloody pus came out, and the Vet took a swab of this for analysis.  Subsequently, she was put onto Baytril for 10 days.  Whilst the hard lumpiness has now gone from the teat in question - the mass has remained, and the teat does not look as though it is shrinking at all. The rest of her teats have gone back as normal, but I obviously cannot show her with this one enlarged teat still so evident. 
Any ideas anybody??

i would get the vet to check it out ......

hows it all going........................
fiona