This article focuses upon reproduction of domestic dogs. Reproduction within other types of canid is not covered at present.

Two dogs copulating on a beach

This article covers the process of reproduction in canines (dogs and their relatives), as well as related veterinary and breeding information. Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Trinomial name Canis lupus familiaris The dog (Canis lupus familiaris) is a domestic subspecies of the wolf, a mammal of the Canidae family of the order Carnivora. ...

Canine sexual anatomy and development

Main article: Animal sexuality

See below for a glossary of terms used in this article.

Animal sexual behavior takes many different forms, even within the same species. ...

General

The female sex of the domestic canine is referred to as a bitch, and the male of the same species is referred to as a stud. In domestic canines, sexual maturity (puberty) occurs between the ages of 6 to 12 months for both males and females, although this can be delayed until up to two years of age for some large breeds. Pregnancy is possible as soon as the first estrus cycle, but breeding is not reccomended prior to the second cycle. As with other domesticated species, domestication has selectively bred for higher libido and earlier and more frequent breeding cycles in dogs than in their wild ancestors. Puberty refers to the process of physical changes by which a childs body becomes an adult body capable of reproduction. ... Dogs and sheep were among the first animals to be domesticated. ... For other uses, see Libido (disambiguation). ...

Dogs

Like most males of any species, the development of secondary sexual characteristics is dependent on the production of testosterone by the testes. Secondary sex characteristics include increased muscle mass, penile enlargement, anal hypertrophy, and development of a gland at the base of the tail. Testosterone levels are also responsible for the sex drive, which is not cyclical. Males are receptive to mating at any time, and are willing to mate even if the bitch is not fertile. The dog's penis has a bone, called the os penis, which provides rigidity regardless of level of sexual stimulation. The remainder of the anatomy is similar to other species. Dogs have a prostate gland and are susceptible to similar problems as humans.

Bitches

The anatomy of the bitch is similar to other mammals. They have two ovaries located caudal to the kidneys in the abdominal cavity. They have a bicornuate uterus, and there is single uterine body which is sealed off by the cervix. The cervix is muscular with fibrous tissue support, and closes in a stellate pattern. The vaginal vault extends to the opening of the urethra in the dorsal wall, at which point it is termed the vestibule. The vestibule makes a steep downward turn and the exit of the reproductive tract is the vulva. Bitches have a clitoris just inside the vulva. Bitches often have a vaginal stricture, which is a remnant of where the vagina and vestibule fused together during embryonic development. This stricture is often asymptomatic and is broken down during mating.

As with most domesticated species, one of the first and strongest effects seen from selective breeding is selection for cooperation with the breeding process as directed by humans. In domestic dogs, one of the behaviours that is noted is the abolition of the pair bond seen in wild canines. The ability of female domestic dog to come into estrus at any time of the year and usually twice a year is also valued. The amount of time between cycles varies greatly among individual dogs, but a particular dog's cycle tends to be consistent through her life. Conversely, undomesticated canine species experience estrus once a year, typically in late winter. Estrus (also spelled œstrus) or heat in female mammals is the period of greatest female sexual responsiveness usually coinciding with ovulation. ...

Most female dogs come into season for the first time between 6 and 12 months, although some larger breeds delay until as late as 2 years. Like most mammals, the age that a bitch first comes into season is mostly a function of her current body weight as a proportion of her body weight when fully mature. They then experience estrus about every seven months until old age. Female dogs do not experience menopause, although their cycles will become irregular and fertility becomes unpredictable as they become older. Dogs over around 7 or 8 years are usually considered no longer appropriate for breeding, but can still remain fertile.

The reproductive cycle

Female cycle

The average length of the reproductive cycle for bitches is 7 months. Bitches reach sexual maturity (puberty) between 4 to 18 months of age. There is a tremendous variability in the maturation age between breeds, and even within a breed of dog. The first stage of the reproductive cycle is proestrus, in which eggs in the ovaries begin to mature and estrogen levels begin to rise. During this stage males are attracted to non-receptive females. Initially, the vulvar lips will swell up and become pliables, there are small amounts of bloody vaginal discharge, and signs of frequent urination and restlessness. Proestrus generally last 9 days. Estrus is the next stage, in which estrogen levels are high, mature eggs are released from the ovaries, and the bitch mentally and physically becomes receptive to copulation. It is only during estrus that copulation will result in pregnancy. During proestrus and estrus, bitches may have a clear to bloody discharge. These stages is often referred to as "heat." The length of these cycles varies greatly between individuals. Proestrus and estrus can last anywhere from 5 days to 21 days. Diestrus is the period following mating. Diestrus lasts approximately 56 to 58 days in the pregnant bitch, and 60 to 100 days in the non-pregnant bitch. During both of these periods, progesterone levels are high. Because the hormonal profile of a pregnant bitch and a bitch in diestrus are the same, sometimes a non-pregnant bitch will go through a period of pseudo-pregnancy. At that time she may gain weight, have mammary gland development, produce milk, and exhibit nesting behaviours. Anestrus is the period of reproductive quiescence. The bitch has no attraction to or from the male. Anestrus generally lasts four to five months. A pair of lions copulating in the Maasai Mara, Kenya. ... False pregnancy, also known as pseudopregnancy or pseudocyesis, is a psychological condition causing a woman to believe she is pregnant. ...

Copulation

When copulating, a male canine initially mounts the female from behind, as with most tetrapods, a position known informally as doggy style. The female will hold her tail to the side (called "flagging") and allow this if receptive. If unreceptive she may sit or lie down, snap, move away, or otherwise be uncooperative or not allow mating. The male will often move about as he tries to get a good purchase upon her, and whilst attempting penetration of his penis to the female's vulva. At this point, the penis is not erect, it is slender and held rigid by a small bone inside, known as the baculum. A pair of lions copulating in the Maasai Mara, Kenya. ... Groups See text. ... This article does not cite any references or sources. ... Sexual penetration (as opposed to outercourse) typically involves the insertion of the penis into a bodily orifice. ... The penis (plural penises, penes) is an external male sexual organ. ... The external genital organs of the female are collectively known as the vulva (plural vulvae, vulvas)[1] or genitalia feminina externa[2]. In common speech, the term vagina is often used improperly to refer to the vulva or female genitals generally, even though, strictly speaking, the vagina is a specific... The erection of the penis, clitoris or a nipple is its enlarged and firm state. ... The baculum (also penis bone, penile bone or os penis) is a bone found in the penis of most mammals. ...

When the male achieves penetration, he will often hold tighter and thrust faster, and it is at this point when he is mating that the male's penis expands. Canine reproduction is different from human sexual intercourse, because human males become erect first, and then enter the female; canine males enter first, then swell and become erect. It has been suggested that Duration of sexual intercourse be merged into this article or section. ...

The male dog has a bulbus glandis, a spherical area of erectile tissue at the base of the penis, which traps the penis inside the female's vagina during copulation as it becomes engorged with blood. [1] The bulbus glandis is an erectile tissue structure unique among domesticated animals to the canine penis. ... Erectile tissue is tissue in the body that can become erect, usually by becoming engorged with blood. ... The penis (plural penises, penes) is an external male sexual organ. ... The vagina, (from Latin, literally sheath or scabbard ) is the tubular tract leading from the uterus to the exterior of the body in female placental mammals and marsupials, or to the cloaca in female birds, monotremes, and some reptiles. ...

Once the penis is locked into the vagina by the bulbus glandis, the male will usually lift a leg and swing it over the female's back while turning around. The two stand with their hind ends touching and the penis locked inside the vagina while ejaculation occurs, decreasing leakage of semen from the vagina. After some time, typically 5 - 20 minutes (but sometimes longer), the bulbus glandis disengorges, allowing the mates to separate. Virgin dogs can become quite distressed at finding themselves unable to separate during their first copulation, and may try to pull away or run. Dog breeders' websites often suggest it is appropriate for those involved to help calm and settle the mating dogs once this stage is reached, if they show anxiety, through until eventual separation. Ejaculation is the ejecting of semen from the penis, and is usually accompanied by orgasm. ... Horse semen being collected for breeding purposes. ... “Virgin” redirects here. ...

Note that similar canine mounting behavior (sometimes with pelvic thrusting) is also used by dominant canines of both sexes. Dominance mounting, with or without thrusting, should not be confused with copulatory mounting, in which the thrusting is short term until a "tie" is achieved. Dominance in the context of biology and anthropology is the state of having high social status relative to other individuals, who react submissively to dominant individuals. ...

Gestation and litters

A Catahoula Leopard mother nursing her litter of puppies.

Dogs bear their litters roughly 9 weeks after fertilization, although the length of gestation can vary from 56 to 72 days. Litter of Catahoula Leopard puppies Taken by Leslie Bickel of the litter of puppies from which her dog came; Molly is the mom. ... Litter of Catahoula Leopard puppies Taken by Leslie Bickel of the litter of puppies from which her dog came; Molly is the mom. ... The Louisiana Catahoula Leopard Dog, also known as the Catahoula Cur, Catahoula Hog Dog, or simply the Catahoula, is named after Catahoula Parish, Louisiana, USA. Of remaining dog breeds, the Catahoula is believed to have occupied North America the longest, aside from the dogs descended from Native American-created breeds. ... Categories: Biology stubs ...

A general rule of thumb is that a mammal will produce half as many offspring as the number of teats on the mother. This rule is altered in domesticated animals since larger litters are often favoured for economic reasons and in dogs, particularly, the great range of sizes and shapes plays a role in how many healthy puppies a female can carry. An average litter consists of about six puppies, though this number may vary widely based on the breed of dog. Toy dogs generally produce from one to four puppies in each litter, while much larger breeds may average as many as 14 pups in each litter. The number of puppies also varies with the mother's age and health, the father's sperm count, the timing of the breeding, and many other factors. a Great Pyrenees pup A puppy is a juvenile dog, generally less than one year of age that has not reached the equivalent of dog puberty yet. ... The Bichon Frisé is an example of a toy dog[1] that requires considerable grooming. ...

Some breeds have been developed to emphasize certain physical traits beyond the point at which they can safely bear litters on their own. For example, the Bulldog often requires artificial insemination and almost always requires cesarean section for giving birth. For other uses, see Bulldog (disambiguation). ... This article does not cite any references or sources. ... A caesarean section (cesarean section AE), is a surgical incision through a mothers abdomen (laparotomy) and uterus (hysterotomy) to deliver one or more fetuses. ...

Since a mother can provide nutrients and care to only a limited number of offspring, humans must assist in the care and feeding when the litter exceeds approximately eight puppies.

Clinical issues

Owners of intact bitches should be aware of pyometra, an acute infection similar in effect to appendicitis which can affect any intact bitch, and which is always very serious and often fatal. The period after heat, when the cervix is closing, is a high risk period for this disease and close attention should be paid for any signs of temperature, lethargy, lack of eating, excessive thirst, or any other indicators of sickness. Pyometra should be treated as a medical emergency if suspected. Contrary to myth, pyometra can strike any intact bitch, whether she has been bred or not, and whether it is her first or tenth season, although it is more common as dogs become older. Pyometra is a disease of the uterus in bitches (female dogs). ... In medicine, an acute disease is a disease with either or both of: a rapid onset; a short course (as opposed to a chronic course). ... An infection is the detrimental colonization of a host organism by a foreign species. ... Appendicitis (or epityphlitis) is a condition characterized by inflammation of the appendix[1]. While mild cases may resolve without treatment, most require removal of the inflamed appendix, either by laparotomy or laparoscopy. ...

Dog breeding

Timing

Breeders and veterinarians have various methods for determining the best time to breed a bitch. Breeders rely on both the visible signs of estrus and modern testing methods when they are trying to decide the best time to breed. Visible signs of estrus (or heat) include vaginal bleeding, vulvar swelling and the female dog responding to a male dog by standing and "freezing" to allow the male dog to mount her. The three most commonly used medical methods for determining estrus are: Blood Progesterone, Blood Luetinizing Hormone(LH), and a Vaginal Smear. The first two test for the level of those hormones in the blood, and a “smear” checks the amount of cornified epithelial cells present in the vaginal secretions.

Many breeders prefer the LH and Progesterone tests because they are highly accurate while the smear method can be unreliable (especially when done by a vet who has limited experience performing this test). However the smear method is still widely used because it is much cheaper, and it's less stressful for the bitch because no blood has to be drawn.

Before the advent of modern testing a breeder might mate the two dogs every two to three days during the bitch's estrus to ensure that fertilization had occurred. Today, most breeders will track a bitch's cycle (usually by Progesterone blood tests) and breed her only during a 3 day window when she is most fertile and most receptive to the male.

A female dog allowed to roam freely during estrus can end up producing puppies from multiple fathers. Breeders might occasionally breed a female to more than one desirable male for various reasons, in which case the only reliable way to determine parentage of the puppies is through DNA testing of the pups. Genetic fingerprinting or DNA testing is a technique to distinguish between individuals of the same species using only samples of their DNA. Its invention by Sir Alec Jeffreys at the University of Leicester was announced in 1985. ...

Procedure

Natural breeding can be easily accomplished between most dogs as long as the bitch is in estrus during the attempt. Simply placing both dogs in the same environment for a few days will usually result in a pregnancy.

If, due to breed characteristics or the stud only being available for a short time, natural breeding is not desirable, artificial insemination can be used. This is often done at a veterinarian's office. An artificial vagina is prepared, which is a conical thin latex sleeve ending in a sterile collection tube. The inside of the latex sleeve is lightly lubricated. The male is allowed to sniff a female in estrus. Experienced studs cooperate readily in the process. New studs often require encouragement in the form of manual stimulation. Generally the male will mount the female, and the collector quickly directs his penis into the latex sleeve. The male emits semen in the normal way and it is collected in the tube. The semen is then drawn up into a long thin pipette. The pipette is threaded through the bitch's cervix and the semen deposited in her uterus. There is ongoing research into techniques for chilling or freezing canine semen. Currently, for high quality breedings, one of the mates is often flown to the location of the other for this procedure.

Amateur breeding

Amateur breeding is also referred to as "backyard breeding." People practice this for a variety of reasons - they may want their dog to experience pregnancy, they may have failed to spay their dog, or they plan on selling the offspring. Due to the huge numbers of unwanted dogs that are routinely euthanized in animal shelters, this type of breeding is generally frowned upon.

Professional breeding arose in response to the evolution of dog shows. As people began to request dogs with very specific characteristics, breeders began to pay careful attention to which dogs were chosen to mate. Breeders also recognized that there were jobs for which no available dog was fit, so they crossed existing breeds to get qualities appropriate for that job.

Professional breeders attempt to improve what they deem the standard of their breed, though in actual fact there is no evidence that those that consider themselves to be professional produce healthier dogs, of higher quality than other individual. Standards are exhaustively described by national breed clubs, and it is organized under the American Kennel Club, but they may be interpreted very differently by individuals. Professional breeders attempt to maximize the good qualities in their lines; however these qualities may be subject to fashion and change over time. Breeders may think they learn which of their dogs are superior by having them compared to other dogs of the same breed in dog shows. However these qualities are highly subjective, and opinion may vary widely among breeders and judges alike. This is why only intact dogs are allowed to compete; the purpose is to choose the best dogs for reproduction. Some breeders are less interested in show status, and may test their dogs' abilities in other activities, such as hunting, pointing, working, herding, or rescue. Some breeders are interested in improving the temperament of their chosen breed, and may work to that end.

Some people believe that there is unifying theme among professional breeders, namely that they have a specific goal for improving the breed. However many seek to achieve these goals by extreme line breeding which ultimately reduces fertility, result in birth defects, and encourages the proliferation of genetic health conditions, and there may be much disagreement about how improvement in a breed is achieved in reality. Sadly very few professional breeders have more than a rudimentary understanding of genetics, which mean that many myths still prevail concerning the heredity of health problems. Professional breeders are often highly protective of their work. While in many cases this may well be laudible, it can sometimes lead to the perception that those new to a breed are amateur or entering for reasons deemed inappropriate, especially if they hold views on breeding that differ from received wisdom.

Spaying and neutering

Main article: Spaying and neutering

Spaying (females only) and neutering (both genders but more usually males) refers to the sterilization of animals, usually by removal of the male's testicles or the female's ovaries and uterus, in order to eliminate the ability to procreate, and reduce sex drive. Neutering has also been known to reduce aggression in male dogs, but has been shown to occasionally increase aggression in female dogs.^[1] Spaying and neutering are the respective processes of female and male animal sterilization, in order to keep them from producing offspring. ... Sterilization can mean: Sterilization (surgical procedure) - an operation which renders an animal or human unable to procreate Sterilization (microbiology) - the elimination of microbiological organisms It can also mean the death of sperm cells due to radiation. ... Look up testes in Wiktionary, the free dictionary. ... // For ovary as part of plants see ovary (plants) An ovary is an egg-producing reproductive organ found in female organisms. ... This article is about female reproductive anatomy. ...

Animal control agencies in the United States and the ASPCA advise that dogs not intended for further breeding should be spayed or neutered so that they do not have undesired puppies.^[2] American Society for the Prevention of Cruelty to Animals (usually referred to as the ASPCA) is a non-profit organization dedicated to preventing the abuse of animals. ...

Because of the overpopulation of dogs in some countries, puppies born to strays or as the result of accidental breedings often end up being killed in animal shelters. Spaying and neutering can also decrease the risk of hormone-driven diseases such as mammary cancer, as well as undesired hormone-driven behaviors. However, certain medical problems are more likely after neutering, such as urinary incontinence in females^[3] and prostate cancer in males.^[4] The hormonal changes involved with sterilization are likely to somewhat change the animal's personality, however, and some object to spaying and neutering as the sterilization could be carried out without the excision of organs. The tone or style of this article or section may not be appropriate for Wikipedia. ... Prostate cancer is a disease in which cancer develops in the prostate, a gland in the male reproductive system. ...

It is not essential for a female dog to either experience a heat cycle or have puppies before spaying, and likewise, a male dog does not need the experience of mating before neutering.

Female cats and dogs are seven times more likely to develop mammary tumors if they are not spayed before their first heat cycle. ^[5] The high dietary estrogen content of the average commercial pet food as well as the estrogenic activity of topical pesticides ^{[citation needed]} may be contributing factors in the development of mammary cancer, especially when these exogenous sources are added to those normal estrogens produced by the body. Dog food containing soybeans or soybean fractions have been found to contain phytoestrogens in levels that could have biological effects when ingested longterm.^[6] A mammary tumor is a tumor originating in the mammary gland. ... The oestrus cycle (also Å“strus or estrous cycle) refers to the recurring physiologic changes that are induced by reproductive hormones in most mammalian placental females (humans and great apes are the only mammals who undergo a menstrual cycle instead). ... Binomial name (L.) Merr. ... Phytoestrogens are chemicals produced by plants that act like estrogens in animal cells and bodies. ...

Gender-preservative surgeries such as vasectomy and tubal ligation are possible, but do not appear to be popular due to the continuation of gender-specific behaviors and disease risks.

Variations for other types of canid

Glossary of terms

Main article: Glossary of terms used in animal husbandry

References

• Siegal, Mordecai (1995). in (editor): UCDavis Book of Dogs. HarperCollins. ISBN 0-06-270136-3. 

Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era. ... May 16 is the 136th day of the year (137th in leap years) in the Gregorian calendar. ...

See also

• Canidae
• Puppy
• Animal husbandry
• Puppy Whelping Birth DVD