So, you've got yourself the cute puppy that you and your family have been yearning for. The kids love her … and they are actually helping out!
She’s a beautiful female, the most adorable thing in the world.
Then, last night, you recall that the neighbor down the road had one of those “nightmare” problems — her pet had an unwanted pregnancy. And you wonder, “how long does a dog stay in heat?”.
Well, the short answer is: about two and a half weeks.
Basics of the Estrous Cycle
Unlike primate species, including humans and apes, who undergo a menstrual cycle, animals that 
Dogs hit puberty — that is, come into heat for the first time — somewhere between eight and fourteen months of age although, in rare cases, an individual can reach puberty as early as six months or as late as two years.
The second heat of your dog will give you an indication of her heat interval. This can vary between four and twelve months. However, the interval you record for your dog, whatever it is, tends to be fairly constant. So, if your pet had her second heat five months after the first, expect her to come into heat every five months going forward.
The Four Stages of Estrous, and the signs
Proestrus
The first signs that your dog is in heat include one or more of the following:
- Swollen vulva
- Bloody vaginal discharge
- Behavioral changes — aggressive with other bitches, interested in males
- Urine marking
- Male dogs are a lot more interested in her
- She may mount other bitches
This stage lasts about ten days, although it can be as short as three or as long as eighteen days (again, this tends to be constant for a specific dog). She is not quite ready to get pregnant, so she will resist being mounted by males.
Estrus
Estrus is defined by a key behavioral change — she will now be willing to be mounted. This phase lasts about seven days, although again, individual variations can reduce this to a day or less, or extend it for up to three weeks.
Other signs that she is in estrus include:
- Vaginal discharge changes from bloody to straw-colored
- Urine marking continues
- Flagging (holding tail up and to one side)
- Lordosis (arching of the back into a concave)
- Upward pointing of her vulva
- Males are very attracted
- She will actively seek males
Most animal professionals define “heat” to include the period of proestrus and estrus. Which means that a typical dog stays in heat for about seventeen days.
If you are interested in breeding your dog, here are some suggested methods that breeders use
- Breed every 48 hours from first acceptance until she refuses to “stand”
- Breed two or three times with a gap of 48 hours between breedings
- Breed on specific days, eg. Days 11 (from first sign of heat) and 13 or 12 and 14
- Breed when the vaginal discharge changes from red to straw-coloured
- Use whatever worked the last time
If you are not interested in breeding your dog, make sure that she’s monitored from the first signs of proestrus to a few days after estrus is complete.
Diestrus
Following estrus, there are two possibilities:
Your pet becomes pregnant. A normal pregnancy lasts between 56 and 58 days.
You will notice any or all of the following:
- She may become very sluggish
- She may experience “morning sickness” (manifested in loss of appetite and/or vomiting). This normally happens about a month after breeding and, usually, last only a few days.
- Some dogs may develop ravenous appetites
Your pet experiences pseudopregnancy. Any dog who has gone through “heat” and has not got pregnant, will experience pseudopregnancy (this is related to hormones). Pseudopregnancy may not be obvious; on the other hand, some dogs will show the following:
- Weight gain
- An enlarged abdomen
- Mammary glands may develop, even to the point of milk production
- Nesting instinct. She will use a surrogate — her squeaky toy or even the cat — guarding it and, possibly, even attempt to nurse it
Anestrus
Anestrus is when pregnancy hormones are “on holiday”. Your pet’s behavior returns to “normal”. This usually lasts about four months, but can vary, in an individual, anywhere from two to ten months.
A Few Final Words on How Long Does A Dog Stay In Heat
Your pet’s heat cycle can be a source of stress. However, once you learn how long your dog stays in heat and the accompanying signs, you will realize that its management is not difficult at all. Remember, particularly, that your pet will follow a fairly specific timetable. All the best.
Calvin is the co-founder and one of the main contributors to dogtemperament.com. He has been an avid dog lover all his life. He enjoys researching and sharing great ideas on how you can avoid common pitfalls of dog ownership and build the most loving and enjoyable relationship with your dog.