My Cocker Spaniel Has a severely swollen tit

My American Cocker Spaniel, Laura, has had a swollen tit near the bottom of her belly for nearly a month. Everyone says this swollem-ness will go away but im afraid of what it could be. She has barely any fleas, since we've bombed the house, but everything doesn't seem to work. Now it's begun to grow purple-ish with a few veins showing up. It's just this one tit. What do I do??

[Aleda M Cheng, D.V.M., C.V.A]

If your dog has not been spayed a swelling in mammary tissue could be breast cancer.  If your dog was spayed before her first birthday or so, than it may not be breast cancer but it could be another tumor, which may or may not be as serious, such as mast cell tumor, histeocytoma, Squamous Cell Carcinoma (or other skin cancer), lipoma, liposarcoma, sebaceous gland adenoma, fibrosarcoma, and the list goes on and on.  It should be biopsied ASAP regardless due to your description and the location.  Since you have fleas it could be skin problem, or abscess, secondary to her scratching, biting or irritating that area, especially if she has flea allergy dermatitis.  Any amount of fleas are dangerous.  Fleas carry a variety of parasites and other infectious diseases some of which can be transmitted to humans.  Fleas are so easy to control and prevent these days using Frontline, Advantage, Advantix, Capstar and others.

You must take your pet to a veterinarian ASAP to have these problems taken care of!