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My dog's acting strange. Is she in heat? What signs to look for?

Updated On September 23rd, 2025

Pet's info: Dog | American Pit Bull Terrier | Female | unspayed | 2 years and 1 month old | 70 lbs

How would I know she's in heat

3 Answers

Most Helpful Answer

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Answered By Jacqueline Nobles, DVM, DACVECC

Veterinarian, Board-Certified Emergency/Critical Care Specialist

Published on December 10th, 2016

The canine estrous cycle or "heat" occurs on a cycle that averages around twenty-one days. Your dog's heat cycle is divided into four phases each of being about different signs. Proestrus: The First Week of Heat Signs: Hormonal fluctuations bring about physical and in some cases personality resulting in more or less affection or even agitation. Your pet may experience changes in appetite. Swelling of the vulva bloody vulvar discharge are common. Bloody discharge from the vulva may be light during the first few days and grow heavier as the week goes by; you may wish to purchase dog diapers or pads to catch the discharge during your dog's heat cycle. Also, your pet may also urinate more frequently during this part of the heat cycle. Estrus: The Second Week of Heat The second week of the estrous cycle is the period during which the ovaries are releasing eggs for fertilization. Signs of estrus include decreased vaginal discharge and standing or allowing males to mount. Diestrus: The Third Week of Heat The third week of your dog's cycle is the end of the fertility phase and you will observe little to no vaginal discharge, reduction in vulvar swelling and cessation of male receptivity. Anestrus: The Resting Period After Estrus If breeding was not successful during the estrus period, your dog will go back into anestrus, the resting period. This period lasts between five to eleven months.

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Other Answers

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    Answered By Andrea M. Brodie, DVM

    Veterinarian

    Published on April 24th, 2017

    First she will go into pre-heat /pre-estrus. Her vulva will swell, and she will start having a bloody discharge for about 9 days to three weeks. This serves to attract males, but she will not be receptive. Then the bloody discharge will get clearer and she will go into heat lasting up to 3 weeks. during that time she will be receptive for the male.

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    Answered By Linda G, MS, DVM

    Veterinarian

    Published on August 31st, 2019

    Hello. The first sign will be swelling of the vulva over about a weeks time. Within days of this, a bloody discharge will be seen. This is proestrus & a female will not be receptive to a male even though a male might be interested in her. This generally lasts a week. Then the female will enter estrus. There should be less blood seen but sometimes more mucous, vulvar swelling will be at the max, & she should stand to be mounted by the male. This too, lasts about a week. Last stage is anestrus & everything returns almost to normal. Some vulvar swelling may remain if she does become pregnant. These are just average times for each stage, sometimes they can be shorter, sometimes they can last almost 3 weeks. Thanks for using Petco Pet Education Center, formerly Petcoach.

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