Some inflammatory conditions may lead to this type of symptoms, but don't worry & get proper examination & treatment from Vet., mean while & additionally with any treatment you may use Canine clan ( wound & Abcess ) supplement powder - 2.5 gm twice in a day dissolving in waler or

Licking or biting around her nipples with redness may indicate irritation, pain, or an underlying medical condition affecting the mammary glands or surrounding skin. Common causes include mastitis (infection or inflammation of the mammary gland), dermatitis due to allergies, bacterial or yeast infections, insect bites, or local skin irritation. Hormonal changes such as pseudopregnancy can also lead to licking and mild swelling of the mammary area. Since the dog is middle-aged, mammary tumours should also be considered, especially if there is a firm lump, asymmetry, or persistent redness. Continuous licking may worsen inflammation, so an Elizabethan collar (E-collar) should be applied to prevent further trauma, and the dog should be taken to a veterinarian for a thorough physical examination to identify the underlying cause and start appropriate treatment.

There are so many reason of this Is she spayed ? If not then any chances of mating ? Or she might be in heat or may be false pregnancy or any uterine infection or any kind of allergies ( less likely ).

It can ve due to infection/ inflammation. We need to check few more details to help her better. Kindly get her checked