Information on the Menstrual Cycle of a Chihuahua

If you are a Chihuahua owner or know someone with a Chihuahua, then you are well aware of how feisty, funny and ferocious these tiny terrors can be. An ancient breed, Chihuahuas have many terrier characteristics which make them alert and vocal watchdogs, as well as loyal and loving lapdogs. If you have a female Chihuahua, you may be curious about breeding her and wondering about when to bring a male Chihuahua into the picture.

The Chihuahua is named after the state of Chihuahua in Mexico where it first became widely-recognized as a singular breed in the 1850s, but its lineage reaches much farther back. Carvings of Chihuahua-like dogs called Techichi have been found on Toltec structures. When the Toltec were conquered by the Aztec, the Techichi became an important part of religious observance and Techichi skeletons have been found in graves alongside human remains, perhaps intended as spirit guides. Later, the Techichi may have been bred with hairless dogs from Asia to become the modern Chihuahua. Recognized by the American Kennel Club in 1904, the Chihuahua quickly grew in popularity throughout the United States and especially in the Southwest.

Although the American Kennel Club sets the weight limit at six pounds for a Chihuahua, these petite pets can be as small as one and a half pounds or as heavy as nine pounds. They can be either short coated or long coated and almost any color and pattern. Their heads are very round, similar to an apple, and their bodies, long and slender with long stick-like legs and tiny feet, resemble a deer's body. Their noses are small and pointed and their eyes large and luminous. Perhaps their most remarkable feature is their huge, bat-like ears that droop, perk and flare to display their emotional state or level of alertness.

Although it may seem as though your Chihuahua has a menstrual cycle (vaginal swelling and bleeding for about nine days), dogs do not menstruate as humans and other primates do. Instead, dogs have an estrus cycle, which occurs (in small dogs like Chihuahuas) every four to six months. Dogs also do not experience menopause but go through this estrus cycle throughout their lives if not spayed. The estrus cycle of a Chihuahua consists of four stages: proestrus, estrus, diestrus, and anestrus.

Just before your Chihuahua begins proestrus, she may start shedding and licking herself. She is preparing to enter proestrus when the vulva swells and a bloody discharge becomes evident. During this phase (which lasts from four to 20 days), she will be very attractive to males but will not let them near her. Near the end of this phase and the beginning of the next, estrus, she will let males approach or even mount her, but will not allow penetration. When the estrus phase begins, she will allow full contact with the male dog. This stage lasts on average nine days.

The third phase of a Chihuahua's estrus cycle is diestrus (also called metestrus). In this phase, your dog will stop accepting males and whether she is pregnant or not, will exhibit pregnancy behaviors, such as trying to nurse other animals or toys. This stage lasts from 80 to 90 days. If she is not pregnant, the final stage, which last about three months, is called anestrus. During this time your dog's body is resting and reenergizing itself so she can begin the cycle of estrus all over again.

If you have a female and a male in your home full-time, nature will take its course, but if you are "borrowing" a male or breeding your Chihuahua through artificial insemination, ask your vet about conducting regular vaginal smear tests at home to check on fertility.