My neutered male 6.5 year old GSD/Husky/Lab developed this growth on his belly a couple weeks ago. It doesn't seem to bother him much. Any clue what it is? One source suggested it could be a Mast Cell tumor.
As mentioned in the comment this is your dogs nipple if you look close you will find more.
It is totally normal all mamals have them(both genders)We have had this question here before for other animals.
Be aware of simmilar looking growths on your pet and contact your vet if you are not able to make a positive identification of what you see.
Nipples have different shapes and colors even in the same breed of animals and their numbers might vary even whithin the same group of babies.