My 1-year-old female dog has lumps under her nipples. What is it?
Hello. This is probably benign mammary hyperplasia, but you do want to have this looked at, especially if she has been spayed. If she has not been spayed & has never been with a male dog, then this could be related to a false pregnancy. Also, has she been in contact with anyone who is on hormone replacement therapy? Sometimes, this can rub off on a pet & cause mammary enlargement. If no outside cause can be found, then have her spayed if that has not already been done, & submit a biopsy to see exactly what is going on with the tissue. Thanks for using Petco Pet Education Center, formerly Petcoach.
Updated on September 23rd, 2025