hard sore/cyst on boxer pups chest

Question
my puppy developed a dime sized lump on her chest just below her nipple overnight. The past cpl days ive put hot compresses &ointment ... Its looking scabbed over but is very hard. It isnt causing her pain but it looks awful & is worrying me.

Answer
Since it is hard and not soft as a sebaceous cyst would be, I would think it is a symptom of something else, or an insect bite.

Please take the puppy to the vet as soon as possible to check it. I would recommend this, because it could be cancerous and needs diagnoses now to treat, or meds if it's a bite of some kind.

Let me know what your vet says.