Dog: Suppression of Heat

Other common/scientific names: estrus suppression

General Information

A female dog cycles every six to eight months. The first phase of the cycle is called proestrus and is characterized by a swollen vulva and bloody vaginal discharge. This phase lasts 7-9 days and the female will not allow the male to mount or breed her during this phase. The second phase is called estrus. The discharge becomes less bloody and the female will allow the male to mount and breed. This phase lasts 5-9 days. Males are attracted to the female during both these phases and can break into the yard or stand vigil outside your door when your female is in heat.

Suppressing the heat cycle can reduce harassment of the male dog, prevent the bloody discharge which can stain carpet and furniture and eliminate the risk of unwanted pregnancy. This can be accomplished with hormone therapy.


Two forms of progesterone (progestins) are available for suppression of canine heat cycles. One is an oral form and another is a long acting injectable form. The oral form is available as a compounded (specially prepared) medication. The injectable form is available from the human market. Progesterone should be given prior to the anticipated heat cycle or in the first three days of proestrus to suppress estrus. Depending on when progesterone is given, the next heat cycle may be postponed for months. It is best to avoid long acting injections or long term oral progestins in dogs intended for breeding.

Side effects of progesterone administration include:


Androgens are male hormones which are also used to suppress canine heat cycles. An oral product is available as a compounded product. This medication must be started at least 30 days before the next anticipated heat but does not have the side effects of progesterone.

Injectable testosterone has been used to for heat suppression but is not recommended. Also, availability is more difficult due to the abuse by human athletes.

While suppressing the canine heat cycle can be accomplished with hormone therapy, spaying your female dog is recommended. In the long run, this provides a much more convenient and healthier way to prevent unwanted cycles.

Update version: 4/24/2014, © Copyright by
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