A Cat's Menstrual (Heat) Cycle

Introduction

The number of days a cat is in heat, the phase of the reproductive cycle when the queen (female cat) is receptive to the tom (male cat), varies. If the queen is not bred, the heat phase may last as little as 2 days or as long as 19 days. In the early spring, some females do not completely come out of heat, and instead the signs of heat just wax and wane.

The Feline Heat Cycle

Queens are induced ovulators. This means that after a few breedings the heat phase will be shorter as eggs will be released from the ovary in response to a hormone surge triggered by breeding. Four breedings will induce ovulation in most queens, while one breeding will produce ovulation in about half of the queens. Ovulation occurs 24 to 72 hours after the breeding.

The full estrous cycle (of which the heat is one phase) may last as little as 4 days or as long as 30 days, with the average being 6 days. Cycling may begin in females as young as 4 months of age or may start as late as 1 1/2 years of age. In a typical cat, puberty occurs at around 8-9 months of age. A typical longhair breed starts her cycle later than a shorthair breed. Most queens cycle from January through October. This is termed seasonal polyestrous cycling.

Signs of heat may be minimal, or in some females so pronounced that an owner may think the cat is ill. Typically a cat in heat will cry, roll over, and in response to petting along her spine, drop her forequarters and elevate her rear with the tail raised and held to the side. She may also be very interested in going outdoors (especially if a tomcat comes calling), and may show increased affection for her human companions.

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