The enlarged and reddish breasts of dogs may be caused by a variety of reasons, including physiological factors and pathological factors.

Physiological factors: During estrus or lactation, the female dog's mammary glands will secrete milk, which may cause the breasts to become enlarged and red. . This is a normal physiological phenomenon and there is no need to worry too much. However, if it is accompanied by other symptoms, such as pain, swelling, etc., you need to seek medical attention promptly.

Pathological factors: Mastitis is one of the common causes of dog breasts becoming enlarged and red. Mastitis is usually caused by a bacterial infection and presents with symptoms such as redness, swelling, pain, and warmth in the breast. Treatment includes antibiotics and anti-inflammatory medications. In addition, some tumor diseases may also cause the dog's breasts to become enlarged and red. These tumors may be benign or malignant and require prompt diagnosis and treatment.

In either case, if you find that your dog's breasts are enlarged and red, please consult a veterinarian for diagnosis and treatment as soon as possible. At the same time, it is also very important to keep the dog’s diet and living environment hygienic.