How many days does a dog's heat cycle usually last?

The duration of a female dog's heat cycle usually ranges from 7 to 14 days. Most female dogs experience their first heat between 8 and 10 months, with some experiencing it as early as 6 months and others as late as 12 months. Large breeds may experience heat later, while small breeds may experience it earlier. Normal sexually mature female dogs have two heat cycles per year, most commonly in March-May and September-November.

The physiological changes that occur during a female dog's heat include several symptoms, such as vaginal bleeding, genital tract congestion, and swelling. Additionally, they may exhibit excitement, restlessness, and reduced appetite. As a dog owner, it is important to distinguish between a normal heat cycle and potential urinary tract issues or pyometra. If in doubt, consult a veterinarian for diagnosis.

Female dog heat cycles follow a periodic pattern, consisting of estrus, proestrus, metestrus, and anestrus. In proestrus, the female dog's external genitalia swell, redden, and become moist, with bloody vaginal discharge. She may be willing to play with male dogs, urinate frequently, but refuse to accept mating. During estrus, the color of the bloody discharge gradually changes from bright red to dark red and finally light red. The female dog actively seeks out and teases male dogs, becoming willing to accept mating. In metestrus, the female dog refuses to mate. At this point, the external genitalia return to normal and bleeding stops. If the dog is pregnant, she will enter the gestation period. Anestrus follows immediately after metestrus, with the reproductive system remaining inactive for about three months.