How long does it take for a dog to menstruate Dogs generally menstruate for 12 to 16 days. Female dogs become sexually mature at about eight months of age and will begin to menstruate. The menstrual period does not bleed but the area where you pee will be swollen and pink fluid will begin to flow for 1 to 2 days. The blood is usually in the form of drops, and smaller dogs will have more than smaller dogs. The dog will bleed for 11 to 14 days during the menstrual period. The owner must help the dog to keep warm, preferably without strenuous exercise, and the owner can also use warm water to gently wipe the swollen area.
