What Is a Heat?
How To Know When Your Dogs In Heat
Estrus (“heat”) is the mating period of female animals. When estrus occurs, animals are said to be “in heat” or “in season.” Dogs generally have their first estrous cycle at 6-12 months of age. Large breeds may not have their first estrus until they are 12-24 months of age.
Female dogs in heat are somewhat similar to a human female in menstruation. During the “heat” cycle, the dog may became pregnant.

The estrous cycle:

1. Proestrus: Starts with the appearance of vaginal bleeding. It normally lasts from 4 to 9 days. Increased swelling of the vulva and possibly an increase in urination. Male dogs become very persistent, but she will not yet mate with them.

2. Estrus: The female will accept the male and conception can occur. The vaginal discharge is more yellowish than bloody. Usually, the stage lasts for 4 to 13 days. Your female will allow any male dog to breed with her at this time.

Metestrus and anestrus: Periods of ovarian activity, but with no symptoms. False pregnancies can occur during metestrus.


The dog will bleed from the vagina, may have swelling of the vulva and increased urination.
Small dogs will of course have less bleeding and the swelling may be harder to spot

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