At ovulation or “heat,” female dogs release pheromones that attract other dogs – especially males – into her environment. While in heat, female dogs may show unexpected behaviors such as sudden mood changes, licking of her genital area and mounting behaviors, refusing food and water consumption and refusing to eat/drink at all. Urine may also increase during this stage as will overly affectionate behavior or whining; if this behavior causes discomfort to you during heat cycle it would best serve your best to keep her somewhere safe during her heat cycle.
Your first experience of having your dog enter heat will likely be challenging. Her body is overflowing with pregnancy-related hormones that can make her irritable and aggressive; her urinating frequency will increase, as will blood-tinged discharge from her vulva; she’ll become very interested in petting as she shows off her new physique; some dogs in heat may even become ill with period cramps that cause them to vomit.
Proestrus phase of a dog’s heat cycle typically lasts seven days and marks the start of her ovulation. At this stage, her vulva may still be swollen but her bloody discharge has likely changed to watery pinkish color, she will start interacting with male dogs as well as showing marking behavior such as urinating near areas in her yard or while out walking as her way of telling male dogs not to come close.
Once her ovulation takes place, she enters the estrus phase of her heat cycle for up to 21 days. While her swollen vulva may become less noticeable and bloody discharge may stop, she remains open to male dogs (or household pets) mounting her and even mounting them himself! Additionally, she will lick her genital area excessively and may urinate more frequently-sometimes leaving urine marks behind!
As your dog comes out of her estrus cycle, her vulva should shrink back down to normal size and any bloody discharge should cease. For her safety and to prevent unwanted pregnancies from taking place during this period, it is wise to keep her in a secure, quiet area until the process has concluded. When taking her outside, always ensure she remains on a leash and away from any fenced in yards. Male dogs can detect her pheromones from miles away and will make every effort to get close enough for a sniff–even jumping fences to reach her–resulting in injuries for both male and female dogs. Keep a spray bottle of water handy to scare off male dogs; this will save both you and your pup much stress. After about a month or two, your pup should return to her usual behavior with no sign of being in heat; her anestrus phase will likely begin shortly afterwards and allow for future breeding opportunities.