The Heat Cycle of Cats
Estrus in the queen (female cat) is defined as the time during the reproductive cycle when she displays interest in mating. Estrus begins when the queen allows the male to mount and breed, and ends when her receptive behavior ceases. In cats, mating behavior is required to induce ovulating.
Domestic cats usually reach sexual maturity (puberty) between five to 12 months, at which time they experience their first estrus. The adult cat is seasonally polyestrus, cycling repeatedly (about every two to three weeks) throughout the breeding season (mid-January to August), unless interrupted by pregnancy or illness. Several major phases compose the estrous cycle, and variations in the level of normal circulating hormones contribute to these different phases.
- Proestrus – the period that precedes estrus when males are attracted to nonreceptive females
- Estrus – the period of breeding, also known as being "in heat"
- Diestrus – the period following mating
- Anestrus – the period of reproductive quiescence; the queen has no attraction to or from the male.
- Nonestrous – the period of hormonal inactivity
What to Watch For
- Frequent vocalization or moaning
- Frequent urination
- Rolling around
- Rubbing the body against objects
- Receptivity to the male
During estrus, your cat may respond to stroking of the lower back and rubbing of the area at the base of the tail by lowering her forequarters so the elbows rest on the ground, raising her pelvis, and moving the tail to one side. There is no vulvar swelling or vaginal bleeding to be noted when a cat is in heat.
Generally speaking, the behavioral aspects of estrus in the cat are diagnostic. If the cat is not cycling properly or seems infertile, then tests are available to determine the general health of the cat and assess reproductive status. These include:
- A thorough history and physical examination are initially performed.
- Baseline blood tests include a complete blood count (CBC), biochemical profile, and urinalysis as a broad general health screen
- A feline leukemia virus and feline immunodeficiency virus are often done.
- Assays of certain reproductive hormones, such as estradiol and progesterone may help identify stages of the estrous cycle.
- Screening thoracic and abdominal radiographs may be considered.
- Abdominal ultrasound and/or and exploratory laparotomy may be done to better visualize and confirm the presence of reproductive structures.
- Vaginal cytology is of little help in documenting the presence of estrus in the cat.
Estrus is a normal physiologic function of the intact female cat. Estrus can be prevented or eliminated by spaying the cat. The medical term for spaying is ovariohysterectomy, which means that both the ovaries and uterus of the cat are surgically removed. All signs of estrus cease within a few days of spaying the cat.
It is not uncommon for pet owners to mistake normal estrus for illness in some cats, as their behavioral changes can be quite remarkable. It is important to know when your cat is in estrus, as it is common for a queen in heat to attract male cats from the surrounding neighborhood. Inappropriate mating is not uncommon, and preventative measures should be taken should keep the cat confined indoors through out the breeding season.