Every since my yorkie puppy had first period her breast have gotten big,is that normal?
Hormones move in…and things get swollen. If they are getting swollen around the nipple, she may be pregnant. If so, way to contribute to our already grossly over bred dog population. GET HER SPAYED ASAP PLEASE!

YES it is!!
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Pretty normal unless it is unusually big. Hormones kicking in here. If you have your Yorkie spayed it won’t happen anymore. It is not called a period with dogs, it’s called a "heat cycle". Hopefully your girl didn’t get bred on her first heat. If you think she did then you will need advice from your vet and pretty quickly.
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Dogs don’t have periods. They go in heat. Is she pregnant? WHY is she not spayed?
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Now that she’s had her first heat she is now at an increased risk of getting mammary cancer later in life. With every heat cycle she goes through, the more her risk increases. Spay her before she goes into heat again.
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Hormones move in…and things get swollen. If they are getting swollen around the nipple, she may be pregnant. If so, way to contribute to our already grossly over bred dog population. GET HER SPAYED ASAP PLEASE!
References :