REPRODUCTION: ESTRUS CYCLE

Q. When does a female dog first come into heat?

A. Puberty or sexual maturity in the female dog usually occurs around six months of age. The smaller breeds tend to go into “heat” earlier and some females can have their first “heat” or estrus as early as four months of age. On the other hand, the large and giant breeds can be up to two years old before they come into heat for the first time.

Q. How often is my female likely to come into heat?

A. On average this occurs about twice a year, although it varies from dog to dog. After the first heat there is often a great deal of variation in the frequency and this is normal.  Some females take a year to eighteen months to develop a regular cycle.

There is no evidence that irregular heat cycles predispose the dog to false pregnancies or pyometra (uterine infection). Small breeds tend to cycle more regularly than the larger breeds. Three and occasionally four heat cycles per year can be normal in some females.

Very large breeds may only cycle once every 12-18 months. In most giant breeds (Great Danes, Irish Wolfhounds, St Bernard’s) a yearly estrus is common.

Q. How long does a “heat cycle” or estrus last?

A. Heat cycles vary, but average two to three weeks for most dogs.  Heat should be considered to begin with the first signs of discharge and with the female paying attention to her vulva. The vulva will begin to appear swollen. It ends when all discharge ceases and the vulva has returned to its normal size.

Q. What are the signs of heat? 

A. The most notable sign is vaginal bleeding. Often this does not become apparent until a few days after the female has actually come into estrus. Vulvar swelling should be taken as the first sign in addition to the female paying increased attention to her rear end. 

From the beginning of the heat period she will be attractive to male dogs but does not usually allow mating until about 8-13 days later. The discharge will usually become less bloodstained at this time. 

Some females experience heavy vaginal bleeding during estrus. If you are concerned, please consult us.

You may also find that she is passing small quantities of urine more frequently. The urine contains both pheromones and hormones signaling to any interested males that she will be receptive soon.

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