Nipple excretions in 3 year old Cairn Terrier

Question
Our three year old Cairn Terrier bitch is not neutered.  Tonight my wife was checking her and found that one nipple of 6 is slightly swollen and when gently squeezed there is a milky excretion.  Is this normal or indication of some issue.  Her last heat was in August of this year and seemed totally normal. She has never been bred.
thanks

Answer
False pregnancies are very common in bitches, and many even secret milk from their nipples when they would have been due to whelp, whether they were bred or not. Yours, however, should be past that point by now as gestation is nine weeks, and you should be able to express something from all of the nipples.

I am concerned that she might have mastitis in that nipple. I could find nothing on the internet about that in unbred dogs, but did find plenty in regard to unbred heifers and does. I was only aware of mastitis being a problem in bitches who have delivered, but if it can happen in cows and goats, surely it can happen in dogs, too. http://www.canr.uconn.edu/ansci/ext/heifermastitis.htm

If this were my bitch, I think I would call my vet and question him about whether or not he thinks she needs to be seen.

Karen