- Mar 10, 2013
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I have a female dog that is 10 years old unsprayed, has never been pregnant, and she's in perfect health. Last check up the vet said he could see her living another 5.I've read that female dogs not spayed before their first heat have a greater chance of developing breast tumors, and this increases to 25% chance of developing breast tumors if the dog is not spayed before her fourth heat. Not all breast tumors are malignant, but if an unspayed dog starts developing breast tumors then spaying will help reduce the risk of the tumors spreading.