The heat cycle in dogs typically occurs twice a year, although this can vary between breeds and individual dogs. It generally starts around six months of age but can also begin earlier or later depending on various factors. The heat cycle lasts approximately three weeks and consists of four stages proestrus, estrus, metestrus, and anestrus. During the proestrus stage, female dogs will exhibit signs such as swelling of the vulva, increased urination, and behavioral changes. Estrus is when they are in heat and are receptive to male dogs for breeding.
