Dogs heat cycleA female Rottweiler can become pregnant around 6 month of age but most common 9 months. They are not sexually mature until closer to 18 months. Therefore it is highly recommend not to breed a Rottweiler or any other dog until after their 2nd heat cycle. Breeding a mentally immature dog will most likely result in the mom neglecting the puppies or having great complications during pregnancy or delivery. There are smaller and larger breeds. While the smaller breed goes into heat or oestrus early and likely have their first heat cycle four month of age. The larger breeds can stay up to 2 years before an encounter into their first heat cycle. Dogs come into heat twice a year or every six months depending on the variety of dog. They have four different stage of reproductive cycle; these are proestrus, estrus, diestrus, and anestrus. They tends to have signs related to physical, behavior, hormonal cytologic and physiologic changes. Poestrus is a stage which occurs when the owners notice changes about the heat in their dog. These stages last for 9 days within the range of 0 to 27 days. When this happen the males dogs will be attracted to the female. Here the estrogen levels will be at it peak and the development of follicles. The vulva usually tends to be swollen with a blood tinged discharge. Then the cytology change (vagina smear) will show mixed types of cells often with red blood cell. Here the male is receptive to the female. Estrus this happen when the female is receptive to the male, the stage tends to last for 9 days which is based on their behavioral signs, but ranges from 4 to 24 days. During this time the fertile period occurs and the vulva is enlarged, but is soften a little. In the vulvae discharge there is decrease in the blood. While the estrogen levels are decreasing the progesterone levels increases. They are a display of predominately cornified epithelial cells in the vaginal cytology. Dietrus – in this stage it last for about 2 months and the female is no longer receptive to the male. Progesterone peaks 3 to 4 week after the start of diestrus and fall to the basal levels when the stage ends while the estrogen is at a low level. Here the decrease and increase which happen in the progesterone will occur regardless if the dog is pregnant. The vaginal cytology shows a shift back in the basal cell with little red blood cells than the proestrus. Anestrus happens in the time between the diestrus and proestrus. The stage will last four months as other breed can be much longer. In this stage the vulva is no longer swollen and no sign of virginal discharge. The uterus tends to use this time to prepare for the next pregnancy. The cytology shows the basal cell. Signs that your dog is in heat period- Swollen vulva- She might allow other dogs to mount her. - They lick their genital area- They appear anxious while in heat.- Frequent urinating.