How to tell if a female dog is in heat

How to tell if a female dog is in heat

How to tell if a female dog is in heat

Heat is another term for estrus (pronounced es-truss) the time of sexual receptivity for in-tact, or unspayed female dogs. What should one look for to tell if a female dog is in heat?

An early sign a female dog may be going into heat is moodiness.

There might be a noticeable swelling of the nipples, more common in false pregnancy.

When a female dog is ready to mate, she will hold her tail up for easy access to her vaginal area and wait for the male to sniff her and make contact.


Step 1


The entire estrus cycle last 12 to 21 days causing the female to become attractive to male dogs, to become irritable and to be sexually receptive.

If there are in-tact males or even neutered males in the household, pro-estrus is the time they will start to become very interested in the female, even more than usual.

This is due to vaginal discharge, which become visible in the pro-estrus OR before estrus stage. It is in this stage the female becomes irritable and testy and can even be aggressive fighting with other females. In pro-estrus the female does not yet want to take a mate and any advances are met with resistance.

Step 2

Actual estrus stage

The actual estrus stage last five to 13 days. It is distinguished from the pro-estrus stage due to the coloring of the vaginal discharge. The now visible yellowish or reddish discharge indicates the female is closer to the mating stage.

The female will have a swollen vulva and will be visibly flirting getting ready to take a mate. It is in the estrus phase where hormones rage and mating takes place.

Step 3

Knowing when

A female dog comes into ‘season’, also known as in-heat or in-estrus most commonly twice a year.

Usually a female dog or bitch comes into estrus between six and 12 months for the first time. Every six months thereafter is normal, or twice per year. The Tibetan Mastiff has one heat cycle per year.

Conception can most likely happen in the middle, somewhere between seven to 14 days out of the 21 day cycle.

If the female’s cycle deviates from this pattern, it could be an indicator of serious health issues.

Step 4


Metestrus is the third stage of the estrus cycle. During this stage, the uterus is readied for pregnancy. If the female was impregnated the eggs will take about a week to attach to the uterine wall.

This stage lasts between four and 14 days.

Step 5


Anestrus means the cycle is over and the resting period between cycles commences. This resting period is usually five to six months in length.

If the female has successfully been kept away from male suitors and fertilization does not occur, then anestrus occurs.

Things Needed
• An in-tact female dog.
• A keen eye.
• Patience.
• A veterinarian if spaying is the solution.

Tips & Warnings
• To avoid pregnancy, the female must be kept away from in-tact male dogs.
• A male dog can smell a female in heat for up to five miles.
• The yellowish or reddish visible vaginal discharge stage, is the stage called estrus where the female is ready to take a mate, usually seven to 14 days into the cycle.


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