How Often Does a Chihuahua Go Into Heat?

Unlike humans, who take years to develop sexually, female Chihuahuas can conceive as early as three months after birth. Pregnancy generally occurs during the heat cycle, a series of phases that change both the attitude and physical appearance of female Chihuahuas. Each phase varies in length, but the entire heat cycle generally occurs every six to nine months.

  1. Proestrus

    • Proestrus, the first stage of the Chihuahua heat cycle, is extremely noticeable to pet owners. For one, female Chihuahuas will start to bleed. The dog's nipples and the vagina also swell. This discharge may draw attention from males, but attraction will not be reciprocated by the female. Chihuahuas rarely engage in intercourse during this phase. Proestrus typically lasts between four and 11 days.

    Estrus

    • Immediately following Proestrus is the Estrus phase. During this phase, a Chihuahua is able to conceive. Unlike Proestrus, females are extremely receptive to male attention. Bleeding is not as intense in this stage. Estrus generally lasts anywhere between five and nine days. If intercourse occurs, fertilization may result, creating a zygote, or fertilized egg.

    Diestrus or Pregnancy

    • If a female fails to conceive, she will enter Diestrus. During Diestrus, females have no desire to mate with males. This phase lasts 80 days. Females that do conceive will enter the pregnancy phase. Owners can generally tell the pregnancy status of their dogs four to five weeks after intercourse. Female Chihuahuas will discharge clear mucous and nipples will swell in size. Pregnancy lasts for approximately 60 days. Pregnant Chihuahuas should regularly visit the vet. Because they are so small, pregnancy complications are common.

    Anestrus

    • Anestrus is the phase between heat cycles and following pregnancy. Females that failed to conceive will show symptoms similar to the Diestrus phase and display no signs of being in heat. They will not bleed or have any discharge, and owners will not notice any swelling in the nipples or vagina. The length of Anestrus depends entirely on the length of the other phases. However, if a female has a fairly regular heat cycle without lengthy phases, Anestrus will last between three and six months. Once Anestrus is over, females begin the Proestrus phase, completing a heat cycle.

    Heat Cycle Symptoms

    • Bleeding is one of the more obvious signs of a heat cycle. Some subtle changes may be noticed as well. Some Chihuahuas may even show signs of personality changes. Attitude varies from dog to dog. Some Chihuahuas may be excessively clingy. Slight depression regularly occurs in Chihuahuas in heat as well. Females may also become extremely aggressive to other animals they know well. At the same time, female Chihuahuas may also be sexually assertive and exert themselves on male dogs.