[header] How to diagnose mastitis in dogs [title] Check for painful mammary glands. [step] If the dog has mastitis, the mammary glands will cause pain for the dog. The breast area will be firm and swollen because of the fluid from the infection, and it will be hot to the touch.
The teats may be enlarged or red. [substeps] The mammary glands may also have pus or blood coming from them.