My dog has a lump on her nipple this happened before but went away but now I'm worried since 3 days ago she poop blood with mucus and she vomited last night brown liquid now she's laying around all day she a shitzhu teacup 5 years old. Pet's info: Dog | Mixed Breed | Female | unspayed | 4 years and 6 months old | 9 lbs

I would recommend that Linda see a vet. The lump may or may not be related to her other signs but vomitting and diarrhea with lethargy can become serious quickly in small breed dogs. Blood in her stool and brown vomitus indicates bleeding in her GI tract so she may be at risk of anemia as well as dehydration. She should be seen asap if she is still vomitting or lethargic and depressed. And mammary cancer is more likely to occur in unspayed females so the lump should be checked out as well. I hope Linda is feeling better soon.

That lump is strange. My first thought is maybe Pandora got hit by something and its like a 'goose egg' on a human. It could also be a reaction to some sort of insect sting or bite. Try giving her an antihistamine for the next 24 hours and pay very close attention to the lump. If it does not go down or she starts acting sick, take her in to see the vet. Obviously, you could also just take her in today to get it checked out. It could also be an abscess but that typically takes a few days to form. I hope this helps to give you an idea of what it could be. Please post again with any further questions!

Although a picture of it would help to determine more specifically the underlying cause of it, differential causes would include lymph nodes enlargement, abscesses, tumoral masses or accumulation of fluid due to venous return impairment. A check up is essential to confirm of these causes and give you appropriate treatment options.