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I have a nine month old female cat and about three months ago and I got a male cat too. We thought maybe my female was pregnant cause her nipples started to swell, and now she has huge golf ball size bumps on her belly. She acts pregnant but not sure.  I was wondering if anyone could help me out. How long does it usually take for tumors to get huge if they are?  This all started when the male cat came to live with us. Help!