my great dane is bleeding but is not in season last one was

Welcome! My name is Dr. Andy. I am a 2003 graduate from UC Davis, and currently a Medical Director of a veterinary hospital.

I am sorry to hear about this concern.

A lump involving a mammary gland is significant. We don't know if this could represent mastitis (mammary gland infection), or a possible cancer.

Definitely, I do feel this is well worth a veterinary examination. The vet may suggest a course of antibiotics if worried about infection, but if feeling like a lump, they may also suggest a simple needle poke test as well.

Fine-needle aspirate test is performed usually without anesthesia and is very quick. Your veterinarian takes a few needle samples from the lump (the needle is no larger than the needle used to give vaccines). The sample is smeared on to microscope slides and submitted to the laboratory. It is not always as definitive as a biopsy (this is a full tissue sample), but often it can yield enough information to help guide you and your vet as to whether a biopsy is needed, or if surgery should be performed.

I hope that information has been helpful.
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Dr. Andy