What to Expect When Your Female is in Heat

Females generally have their first heat cycle around six months of age. Depending on the breed and size some dogs can cycle as early as 4 months, others as late 2 years old.

On average this happens about twice a year. Initially there could be a great deal of variability between cycles, some females take 18mos – 2 yrs to develop a regular schedule.

Heat cycles vary in length but average two to three weeks for most dogs

Phases of the Heat Cycle

1st - Proestrus is a 10-day period characterized by a swollen vulva, a bloody vaginal discharge, and attraction of male dogs. She flirts with the male but will not allow him to mount. The bloody vaginal discharge is what seems to lead to the misconception that the dog is menstruating. In fact, the blood comes directly from the walls of the vagina rather than the sloughing of the uterine lining as occurs in menstruation.

2nd –Estrus lasts for 5-9 days and is the time when she ovulates. It is characterized by the change in color of the vaginal discharge from bloody to straw colored. At this time the female begins to allow the male to mount. Generally it is during the change from proestrus to estrus that the female is most fertile.

3rd – Diestrus 6-10 weeks; this begins either after the discharge or after mating and fertilization. During this time progesterone is produced in the ovary. If the dog is pregnant, other hormones will eventually take over to maintain the pregnancy. If she is not pregnant, the corpus luteum must simply wear out before she goes back into the period of hormonal inactivity in which she spends the bulk of her time.

4th - Anestrus usually lasts for 15 weeks. Your dog won't have any hormonal activity, produce milk or possess an interest in mating. When a female dog is in heat, both she and the intact males in her vicinity will show changes of behavior, and many of the spay/neutered dogs in the vicinity will, too. Two or more female dogs in the same home will in many cases not be able to get along, especially if one or more of them are intact.

Expected Behaviors

  • Increased risk of aggression
  • Estrus can cause moodiness, and hormone changes. Her attitude can change overnight. If your dog is going to have contact with children, that's another reason to seriously consider spay/neuter.
  • signs of pain that may be similar to cramping in humans
  • an increased urge to get out of the house or fenced yard. You won't be able to leave her outdoors unsupervised for even a second because the scent of her urine (she will urinate quite frequently) attracts males from up to a mile or so away.
  • Some dogs stay clean, while others may leave stains around the house. You can expect to see bleeding On Average for 2 weeks.

False Pregnancy

A false pregnancy may occur in a dog, regardless of whether or not she was mated. The majority of intact female dogs will show some signs of false pregnancy after an estrus cycle. After the female dog has an estrus cycle, her ovaries begin to produce hormones, regardless of whether she is pregnant or not. If the dog is pregnant, the hormones will continue to be produced until shortly before the puppies are born. If she is not pregnant, the levels of the hormones begin to decline after 4-6 weeks. The increased levels of circulating hormones cause changes that mimic pregnancy. As the hormone levels decline in the non-pregnant dog, they send signals to the body that stimulate false labor and mammary gland development. The severity of the symptoms vary. Behavioral changes of false pregnancy include:

-Mothering activity

-Decreased interest in physical activity


In mild cases treatment is not necessary and symptoms will subside in approximately 14-21 days

Benefits of Spaying

  • Ovariohysterectomy ("spaying") is the term applied to the surgical procedure involved in the removal of the uterus and ovaries of a female dog.
  • Spaying the dog prior to ever beginning heat cycles can spare both her health and her temperament. Spaying helps produce healthy and good-tempered dogs.
  • An Ovariohysterectomy eliminates most, of the female hormone production. Estrogen is one of the primary causes of canine breast cancer, the most common malignant tumor in dogs. Animals that are spayed around one year of age very rarely develop this malignancy.
  • We are now recommending spaying your dog at 4-16 months of age to avoid this and other complications.