My brother has a 7 year old German Shepherd who just went out of heat and has licked and bitten one of her nipples until total infected? Is there an answer to this or is it a normal occurance?
Well obviously she's going to need to be seen by a Vet as soon as possible, as a human would if they had an infected nipple.
She may have bitten it so severely because she is in pain...maybe the the hormone change had caused a bit of mastitis. It could be serious, so no diagnosis should be assumed without seeing the Vet.