Reproduction

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While the goal of reproduction is always the same – the birth of healthy puppies – the resources for achieving this vary greatly between private owners and professional breeders. Owners of a companion or working dog will sometimes mate their dog to obtain puppies with comparable qualities, but reproduction is not vital to a dog’s psychological or physiological balance, as many people mistakenly think. Participation in reproduction is closely related to hierarchical status in wild dog packs, because mating is a sign of dominance, which sometimes explains incompatibilities of character between mating dogs.

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Meticulous selection

Breeders select their breeding stock based on ancestry, offspring and genetic traits. They manage to sidestep the hierarchical aspect by assisting and directing mating between dogs of their choosing. And if one or both of the dogs refuse to cooperate, they can employ artificial insemination to get what they want.

Mating

After the partners have been selected and the approximate moment of ovulation determined, the female is presented to the male – the stud – for mating. For reasons of hygiene, it is worthwhile checking the genitals of both dogs for lesions. This will limit the risks of transmission of STDs such as canine herpes virus. The genitals must be clean, and regular blood tests are preferable to the use of antiseptics, which often have spermicidal qualities that can prevent fertilisation.

In longhaired females, the hair around the vulva may be smoothed, separated or clipped to make penetration easier. Mating is preceded by a short period of wooing and smelling, which increases the excitement of both dogs. The erection caused by the rigidity of the penis bone (os penis) and the inflow of blood into the erectile tissue enables the male to insert the penis. This triggers contractions of the vagina, which favours the ascent of the spermatozoa, maintenance of the erection and tying during ejaculation.

Grossemy

This phase should last for at least five minutes, but can last for up to half an hour if the female’s movements maintain stricture of the erectile tissue. In most cases, if the time is right, the male and female will manage perfectly well on their own and there will be no need to disturb them. Discreet remote observation (or by CCTV link) will generally be enough to verify that the two dogs have accepted each other and that tying has occurred. Fertilisation can occur without tying, but litters will generally be smaller.

Despite advancements in the diagnosis of ovulation, it is always a good idea to repeat mating after 48 hours, although more than two matings will not be necessary if the female’s ovulation has been monitored correctly.

While the risk of superfecundation (fertilisation of a female by more than one male) is lower in dogs than in cats, it is advisable to isolate other males until all signs of oestrus have disappeared.

Superfetation (fertilisation of an ovum in an already pregnant female mammal) does not occur in dogs.

Artificial insemination is available if natural mating between the selected male and female proves impossible for any reason.

© Diffomédia/Royal Canin

Pathology of reproduction

Infertility in females

© Diffomédia/Royal Canin

Fertility in a population is never 100% in any species. The maximum fertility observed in dog kennels where reproduction conditions are optimal does not exceed 85%. It is actually recommended that females do not mate during at least the first oestrus every other year.

With this in mind, infertility should not be suspected until the female has remained infertile during oestrus for two successive periods. That said, the veterinarian does not need to wait so long before running a few tests if fertilisation does not occur.

The veterinarian will start by checking the male’s semen and investigating recent offspring. If this does not identify anything of concern, attention should be turned to the female. There are a great many potential causes of infertility in females. An extensive investigation, covering earlier cycles, any treatment (especially hormones), the date of mating, how it went and the nature of vulval discharge will help to identify the cause, be that a problem with egg production, fertilisation, implantation or gestation. Normal fertilisation requires healthy genitals, proper ovulation, copulation or insemination during the optimal period of fertility, good-quality semen and the maintenance of gestation for two months. Any abnormality in these areas can cause infertility.

• Ovum production abnormalities

Possible causes of abnormal ovum production:

• Linked to the absence or stunted development of oocytes in the ovary (oocyte maturation disorder), manifesting as nonexistent, discreet or irregular oestrus.

• Due to an obstruction of egg release, sometimes manifesting as the appearance of cysts in the ovaries, which can result in nymphomania, extended or permanent oestrus.

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Cysts can result in nymphomania, extended or permanent oestrus

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• Consequence of hormone treatments (anabolic steroids, progestogens, corticosteroids) or excessive sports training (excessive secretion of male hormones in female sporting dogs).

• Consequence of hormone dysfunction (thyroid or adrenal gland disorders, obesity).

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In dogs, hormones essentially cause all these disorders, so the veterinarian must complement the diagnosis with hormone measurements.

Treatment obviously depends on the origin. The absence of puberty cannot be treated in the same way as an androgen level disorder, even though the fundamental problem is the same (absence of follicular maturation).

Treatment obviously depends on the origin. The absence of puberty cannot be treated in the same way as an androgen level disorder, even though the fundamental problem is the same (absence of follicular maturation).

Hormone treatments are prescribed to stimulate the defective glands or replace the deficient hormones. The veterinarian will always use hormones with prudence, as their administration can cause the glands normally responsible for producing them to shut down temporarily or for good. For example, the use of progestogens in prepubescent bitches to slow down the appearance of first oestrus can stunt growth and stop their cycles temporarily or permanently.

It is therefore vital to refrain from all preventive or curative hormone treatments unless the cause of the infertility has been clearly identified. Hormones are a last resort when all other treatments fail.

• Fertilisation abnormalities

By far the most common reason for non-fertilisation of a female is the choice of the wrong date for mating or insemination. Once this potential cause has been eliminated the veterinarian will study any obstacles that may have prevented the gametes from uniting.

Labat

Vaginal, uterine, urinary or even prostatic infection may provoke the destruction of spermatozoa or disrupt their advancement prior to fertilisation. Likewise, an obstruction of the fallopian tubes (oviducts) due to salpingitis (inflammation of the fallopian tubes) can stop the ova from advancing.

• Implantation abnormalities

Once the ova have been fertilised the eggs divide several times but remain free in the uterine horns before implanting themselves in the mucosa of the uterus, which must be ready to receive them to enable the formation of placentas and thus provide the nutrition needed for the embryos to develop.

Many obstacles (infection, glandular-cystic hyperplasia etc.) can hamper this process. Likewise, if the interval between oestrus is too short the uterus will not have time to return to its initial shape and will not be able to accommodate embryos. Some treatments give the uterus the recovery time it needs.

Some dietary deficiencies (vitamins A and E) have an impact here, but they usually cause much more conspicuous symptoms suggestive of malnutrition before this stage.

• Gestation abnormalities

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Embryogenesis is the process by which an embryo forms and develops, with the concomitant differentiation of tissues.

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Embryogenesis is the process by which an embryo forms and develops, with the concomitant differentiation of tissues. During this process the foetus is particularly sensitive to any disease or poisoning that the gestating female may suffer from. The need to limit all risk of mortality or malformation is why no medical treatments are recommended during the first 20 days of gestation.

Gestation can be spontaneously terminated for many other reasons:

• Genetic incompatibility between the male and female when both have a lethal recessive genetic disorder that renders homozygote embryos non-viable.

• Some chromosome disorders.

• A large number of microorganisms that are reputed to be abortive or teratogenic:

– Viruses: herpes, canine distemper virus

– Parasites: toxoplasma

– Bacteria: salmonella, pasteurella

– Some of these are endemic, such as canine brucellosis in the United States.

• All traumas, either physical or psychological, can sometimes provoke complete or partial abortion (expulsion of part of a litter and continuation of the gestation to term).

• Involution of the corpus luteum, which secretes progesterone, an essential female hormone throughout gestation. This is known as luteal deficiency.

© Diffomédia/Royal Canin

Pseudopregnancy and lactation

Lanceau_Royal_Canin

These disorders are not considered to be pathological insofar as they are more commonly observed in wild dogs than in domesticated dogs, where they recede spontaneously after a few weeks in the absence of treatment and generally have no after-effects.

Females suffering from pseudopregnancy (false pregnancy) present all the symptoms and hormonal changes expected in regular pregnancy without them being pregnant. This further complicates diagnosis because behavioural changes, such as a tendency to hoard objects, weight gain and even lactation cannot be used to determine the female’s status.

The development of the mammary glands is stimulated by prolonged exposure to serum progesterone during dioestrus. At the end of gestation the drop in progesterone is accompanied by a rise in the concentration of prolactin, the hormone responsible for milk production.

This disorder is curiously rare among dogs living in kennels, affecting privately owned females to a greater degree.

Pseudopregnancy does not seem to be an unappeased desire for pregnancy as it can also occur in females that have previously given birth.

Unlike pseudopregnancy, spontaneous lactation is a common reason for visits to the veterinarian. Excitable females will constantly lick their mammary glands, which are swelled up with milk, prolonging lactation by a neuro-hormonal mechanism identical to the suckling reflex.

Lactation during pseudopregnancy is treated with anti-prolactin drugs. During treatment the owner must refrain from massaging the area around the mammary glands and prevent the dog from licking by fitting an Elizabethan collar. This will break the cycle. Removing the ovaries is the only way to ensure pseudopregnancy does not reoccur. This is generally performed as ovariohysterectomy (spaying).

Metritis

Duhayer_Royal_canin

Metritis is a range of uterine infections that generally only affect females during a very specific part of the oestrus cycle. The most common cause is pathogens that enter the uterus when the neck is open, either during oestrus or after whelping. When the neck closes and dioestrus occurs (increased progesterone), metritis can be aggravated by the accumulation of pus in the uterus, known as pyometra.

Pyometra

The symptoms of pyometra may be inconspicuous if there is no purulent discharge from the vulva (closed pyometra). This is the serious form of pyometra because it does not drain spontaneously. There are three main reasons for this:

• The neck of the uterus is closed.

• Circulating progesterone maintains relaxation of the uterus as if gestation was ongoing.

• The horizontal position of the uterine cornua (horns) does not facilitate spontaneous drainage.

In clinical terms, pyometra often provokes lethargy combined with increased water intake and increased urination (polyuria/polydipsia). This can be complicated by an attack on the kidneys by the secreted toxins. The veterinarian can confirm pyometra with a vaginal smear, abdominal palpation, blood tests, X-rays and ultrasound.

A considerable quantity of pus (several litres) can accumulate.

Rapid response is essential. Medical treatment involves the use of antibiotics and hormones (anti-progestogens, prostaglan-dins) that contract the uterus and open the neck to allow drainage. This treatment can only be given to less severely affected females that the breeder wishes to use in reproduction. The treatment of choice is the removal of the uterus and the pus it contains if the female is to make a full, fast recovery.

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Is it true that every bitch should have puppies at least once in a lifetime, for reasons of health and wellbeing?

There is no scientific evidence showing that pregnancy prevents genital tract diseases in the bitch. The view, that having the puppies at least once in a life time is beneficial for the bitch’s wellbeing is anthropomorphic.
In bitches not intended for breeding (pets) spaying should be carried out at a young age. When performed before the first oestrus (heat), it significantly decreases the risk of later development of mammary tumours. It is obvious that neutering prevents pyometra and false pregnancy.
For breeding bitches it is optimal to have one litter per year. When retiring, at 8 years of age, these bitches should be spayed ( neutered) to prevent uterine and ovarian diseases.

Nizanski

Wojciech Niżański, PhD, DVM
Department of Reproduction, Faculty of Veterinary Medicine, University of Environmental and Life Sciences, Wrocław (Poland)

Ovarian and testicular tumours

In medical terms, a tumour is simply an abnormal growth of tissue. Tumours can be either benign or malignant (cancerous tumours). Watery or fatty cysts and abscesses are not tumours.

Cancerous tumours rarely grow in the ovaries of dogs (they account for around 1% of canine cancers), but they are more difficult to diagnose than testicular tumours, which are usually visible or palpable.
Most ovarian tumours secrete hormones that disturb the sexual cycle and lead to symmetrical and bilateral hair loss on the flanks or thighs. This clinical presentation may be complicated by abdominal distension due to ascites (accumulation of fluid in the abdominal cavity). Diagnosis is possible by X-ray, ultrasound, laparoscopy or cytological examination of drained fluid. In the absence of peritoneal metastasis, removal of the ovaries is preferred to any other cancer therapy.

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In medical terms, a tumour is simply an abnormal growth of tissue. Tumours can be either benign
or malignant (cancerous tumours).

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Testicular tumours are the second most common tumour in male dogs after skin tumours. They should be suspected even in the absence of pain or swelling if an older dog presents with hormone problems (feminisation syndrome), prostate hypertrophy, infertility or localised hair loss. The retention of one or both testicles in the abdomen classically predisposes older dogs to such tumours.

Undescended testis

Grossemy

In the embryo, the testes and ovaries are located in the same position in the abdomen behind the kidneys. While the ovaries do not move, the testes migrate through the inguinal wall to the scrotum under the influence of hormones and the traction of a ligament (gubernaculum testis). The testes need to be in the scrotum following puberty because spermatozoa production requires a lower temperature than body temperature. Migration actually occurs in the days immediately after birth.

Ectopia (malposition) of the testes is known as monorchidism when one testis is affected and cryptorchidism when both testes are affected. Inguinal cryptorchidism, for example, is a double ectopia of the testes, which can however be palpated by the veterinarian in the inguinal region.
The testes do not reach their final position in the scrotum until much later (six months on average) and they can sometimes move back up into the groin temporarily in cold weather or when the dog lies on its back. The veterinarian must always check for this abnormality when the puppy is first presented by the new owner and make a note in the puppy’s records. Medical treatments to stimulate migration are generally ineffective, especially when they are started late (after six weeks).

Ectopia of the testes is common in dogs and it is a valid reason for cancelling a sale if confirmed at six months of age. Dogs suffering from monorchidism are perfectly capable of fertilising a female, but it is not advisable for them to mate as they can pass on this defect and they are not considered to conform to the breed standard.

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There can be serious consequences for the dog’s health too, as dogs with undescended testes are around ten times more likely to develop cancer during adulthood (around 5-6 years old on average). Removal of undescended testes in young adults is therefore highly recommended.

Infectious diseases

A large number of bacterial and viral infectious diseases can affect reproduction, causing infertility, metritis, abortion or neonatal death.

Most bacterial diseases that affect the genitals are difficult to diagnose with certainty, because, while it is easy to isolate bacteria in samples (from the vagina or prepuce, for example), it is much more difficult to prove they are responsible for the symptoms in question. The sample may simply be contaminated by urine, vaginal mucus or prostatic fluid.

Abundant abnormal discharge from the genitals in either sex must be analysed and treated by a veterinarian with the appropriate antiseptics or antibiotics. It should be noted however that antibiotics are not effective against viral infections, including canine herpes virus.

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Quantity of spermatozoa in ejaculate

© Diffomédia/Royal Canin

The number of spermatozoa in ejaculate varies, depending on the ejaculation frequency, size and age of the dog. Large dogs produce more than small dogs. Old and very young dogs produce less than dogs in midlife. The total number of spermatozoa in dog ejaculate varies between 300 million and 2 billion. On average, a not inconsiderable probability of fertilisation is estimated when the ejaculate contains at least 150 million normal, mobile spermatozoa.

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Criteria for good-quality semen

Rivière

- Macroscopic appearance in the three phases:
• Urethral phase: transparent to cloudy
• Sperm phase: cloudy to milky
• Prostatic phase: transparent
- Mobility: > 60-70% mobile spermatozoa
- Concentration:
• Small breeds: around 250 million spermatozoa / ejaculate
• Medium breeds: around 750 million spermatozoa / ejaculate
• Large breeds: around 2 million spermatozoa / ejaculate
• At least 150 million living spermatozoa are needed to ensure fertilisation
- Percentage of abnormal forms: more than 30-40%
- Ejaculate pH: 6.3-6.7

Assisted reproduction

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Artificial insemination or assisted reproduction is regularly performed for anatomical reasons, incompatibility of mood or to improve the genetic pool in a breeding programme by using the sperm of a dead stud or a stud in another country.

Determining the best moment for mating or insemination

If artificial insemination or assisted reproduction is to be successful, it is essential to know when the female is most likely to be fertilised.

Ways of determining the best moment for mating

Bearing in mind that spermatozoa remain fertile for around 48 hours in the female’s genital tract, it is possible to optimise the likelihood of fertilisation by ensuring that the gametes come together at the best time. Ideally, mating or insemination should be carried out in the 48 hours following the release of the egg to ensure fertile ova and spermatozoa meet at the best time in the oviducts (fallopian tubes). The ova remain fertile for two days after maturation (this appears to be more than four days in some breeds), which explains why superfecundation – the fertilisation of different ova in the same cycle by different dogs – is possible.

The trick is to closely monitor all the biological signs of ovulation, which are of varying reliability.

• Lighter vulval discharge is generally a sign of the end of pro-oestrus, although it is not a reliable sign of ovulation. Some breeds, such as Chows-Chows, can bleed right through to the end of oestrus.

• Mating practised systematically twelve days after the first blood loss and repeated two days later is a practical solution, provided the first blood loss is properly observed. This is, however, an imprecise method, because 20-30% of females ovulate outside of this period, which results in either no litter or a very small one.

• Acceptance of the male or the stud and the lateral deviation in the carriage of the tail are not very good criteria either. Some females will allow copulation at the start of pro-oestrus despite not actually ovulating for up to another thirty days. Females may also allow copulation when they are experiencing phantom oestrus during labour, urinary tract infections or in the event of oestrogen secretion by follicular cysts manifesting as nymphomania.

© Diffomédia/Royal Canin

• The resistance of the vaginal mucosa can also be measured using a galvanometer to evaluate the fluidity of vaginal secretions to a fairly precise degree. However, due to the length of the vagina, measurements cannot always be taken in the same place, which means they are difficult to repeat. Furthermore, in daily use this device requires very careful disinfection to avoid initiating vaginitis.

• Test strips to identify biochemical variations in the vaginal mucus are difficult to insert far enough into the vagina to avoid urine contamination. The results are generally imprecise (change in colour in the three days before or after ovulation) and therefore unreliable.

• Vaginal smears enable immediate visualisation of the changing appearance of the vaginal cells, shown by different colours, correlated to hormone variations – especially oestrogen. This simple, economic technique is routinely used by breeders and veterinarians to estimate the stage of the oestrous cycle.

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Observation: Procedure for vaginal smears

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First the swelling of the vulva is examined and the corners pulled down, before the swab is inserted along the caudal wall of the vagina to avoid bumping into the clitoral fossa. Once the roof of the vagina is reached, the swab is revolved horizontally and pushed as far as it goes without applying force. Due to the circular movements, secretions and cells are collected from around the neck of the uterus.

The swab is typically red at the start of oestrus, pinker at the best time for mating, brownish at the end of oestrus and purulent in the event of an infection of the vagina or uterus.

The end of the swab is delicately rolled onto a clean slide without smearing the same area twice, which could create a cell mass.

The sample is fixed with a natural agent for submission to the veterinary surgery or coloured for immediate examination.

Vaginal smears provide much more information than simply the time of ovulation. They can be used to look for any spermatozoa (which survive for up to six hours after mating) if the female has escaped or is suspected of mating through a fence. In this case, they also provide information allowing evaluation of the risk of fertilisation depending on the stage of the oestrous cycle. For example, the risk will be significantly lower if the female is in anoestrus, the start of pro-oestrus or dioestrus, in any event lower than the risk of early medical abortion.

Vaginal smears can also be used to confirm anoestrus, in the event of treatments that are contraindicated during periods of sexual activity, including most hormone therapies.

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Vaginal smears enable immediate visualisation of the changing appearance of the vaginal cells, shown by different colours.

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As part of a hormone therapy they can be used to diagnose some causes of infertility (silent or anovular oestrus, persistence of a secreting corpus luteum, vaginal infection).

Vaginal smears are very useful in canine reproduction, not least because they are fast, economical and easy to perform. For most females, vaginal cytology is a very useful branch of biology and certainly a good way of identifying the period just before and after ovulation. When these females are mated with dogs with good-quality semen, there is a very good likelihood that fertilisation will occur. On the other hand, a more precise method for determining ovulation – such as measuring the blood progesterone level – will be needed if the smear is difficult to interpret, there is a lot of money involved, the quality of the semen is low to medium, or refrigerated or defrosted frozen semen is to be used.

Observation: Measuring blood progesterone

Lanceau_Royal_Canin

In some domesticated female animals (cows, cats) progesterone is typically only secreted after ovulation. In dogs, however, the ovaries start releasing progesterone at the LH (luteinising hormone) peak, which is 48 hours prior to ovulation. The blood progesterone, which was basal during the whole of pro-oestrus, can be detected before ovulation. To benefit from the advantages of this technique, measurements should be started sufficiently early during oestrus and blood tests taken based on the veterinarian’s advice. Between 2 and 5 measurements are often sufficient to monitor standard oestrus.

Blood progesterone at the moment of ovulation will be 4-9 ng/ml, depending on the female and the laboratory. It is important to note, however, that results can only be interpreted in relation to the norms of the laboratory that conducts the test.

The optimal time of mating is 48 hours after ovulation (which is the time it takes the ova to mature).

Advantages of monitoring oestrus

When a precise protocol is followed, the combination of vaginal smears and blood progesterone measurements is a very good way to monitor oestrus, which has many benefits.

• Increased fertility

50-80% of females that are not fertilised after mating are actually mated at the wrong time, so proper oestrus monitoring will resolve infertility in 50-80% of cases.

When combined with a clinical examination, regular blood progesterone measurements in infertile females allow the identification of an anovular cycle, embryo resorption associated with the involution of the corpora lutea, absence of puberty or androgen impregnation, which can have very different treatments.

• Larger litters. Mating the dogs at the best possible time ensures that the maximum number of spermatozoa comes into contact with the maximum number of ova, which leads to a maximum rate of fertilisation in physiological conditions.

• If mating demands a long journey, monitoring oestrus will optimise costs by limiting the risk of failure and the length of stay.

• Monitoring oestrus also improves mating conditions. The female will be happy to participate, minimising the risk of injury and the time needed.

• Because the day of ovulation can be precisely determined, so too can the day the female is likely to give birth (63 days after ovulation, give or take a day either side), which will allow the right preparations to be made in case a Caesarean section has to be performed. If the C-section is performed too early, the puppies will be premature and will typically die a few hours after birth due to respiratory failure. If it is performed too late, the brain will be starved of oxygen in the birth canal. The viability of the canine foetus is conditioned by the late release of a lung surfactant, which determines the respiratory capacities of puppies at birth. This pulmonary maturation is precisely concomitant with the drop in the progesterone level in the days prior to the ideal whelping date. If the ovulation date has not been precisely determined, the mother’s blood progesterone level will provide the veterinarian with vital information for determining whether the puppies will be able to survive a C-section. Monitoring oestrus and, where necessary, using the progesterone level before a C-section significantly increases the survival rate of puppies born by C-section, especially Bulldogs, which account for more than 90% of all C-sections.

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Neutering

Ovariohysterectomy is almost a “standard” recommendation for bitches.
There are two medical reasons to spay bitches. First reason is the prevention of mammary tumours. When ovariohysterectomy is performed prior to the first heat in a bitches, the risk of mammary cancer later in life is less than 1%, compared with ovariohysterectomy performed after the second heat when the risk is about 25%. The second option is to avoid the risk of pyometra.
For males there are other benefits: decreased risk of prostate hypertrophy and all accidents related to females in heat.

Serdean

Dr. Calin Serdean, DVM
Specialist in ultrasound examination
(Rumania)

Artificial insemination

Artificial insemination – which was first achieved in Italy in 1780 – is any reproduction technique that requires the assistance of humans.

Insemination with fresh semen

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Artificial insemination with fresh semen involves taking the semen from the male in the presence of the female, checking its quality and inseminating it immediately. This technique is used when the male and female are unable to copulate, due to:

• Incompatibility of mood

• Wish to protect the male from STDs

• Inexperience of one or both of the dogs

• Narrowness of the genital tracts (vulvar atresia, vulvar or vaginal malformations, vaginal prolapse connected to oestrogen impregnation during oestrus)

• Pain suffered by one of the dogs during mating (in the vertebrae, hindlegs, penis or vagina)

• Lack of sex drive

• Disproportion in the size of the dogs (male too big or too small)

After checking that the female is receptive the veterinarian will take a semen sample from the stud in the presence of a female in oestrus (not necessarily the female that is to be inseminated). This is achieved as follows:

• The erectile bulbs must be uncovered under the prepuce before a sample is taken to ensure that their swelling does not prevent their total exteriorisation.

• The erectile bulbs are then massaged until the pelvis starts to move spontaneously.

• Stricture behind the bulbs enables the erection to be maintained during the three ejaculation phases, supplemented with massage of the perineum where necessary. The veterinarian then separates the three fractions of the ejaculate, which enables adjustment of the quantity of prostatic fluid (phase three) and use of an appropriate volume compared with the size of the female. Insemination of too little semen will risk failure; insemination of too much dilutes the spermatozoa and may cause the semen to flow beyond the genital tract.

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Once the sperm has been harvested it is examined under the microscope on a heated plate to check the number, appearance and mobility of the spermatozoa. If the quality is satisfactory, the sperm will be introduced into the female’s vagina or uterus using a catheter. Flexible insemination catheters equipped with a balloon (Osiris vaginal catheter) and rigid catheters (Scandinavian catheter) are available.

The female’s hind legs should be raised for ten or so minutes at the end of insemination to favour the advancement of the spermatozoa and limit reflux. Allowing the female to urinate within a few minutes of insemination is not recommended for the same reason.

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Precautions must be taken during the whole of this process to ensure the spermatozoa are not exposed to thermal, mechanical or chemical shock. If this is done and the oestrous cycle has been monitored, insemination with fresh semen will be just as successful as natural mating, with a fertilisation rate of 70-80% or above, as you can be sure that semen of good quality has been correctly deposited at the base of the vagina.

Insemination with refrigerated semen

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Insemination with refrigerated semen is mainly used when the physical distance between male and female makes travelling difficult or expensive.

A veterinarian takes the stud’s semen and refrigerates it at 4°C in a protective, nutritious solution after its quality has been checked. It is then sent in an isothermal receptacle to the female’s veterinarian for insemination after a further check of its quality.

The process must be perfectly synchronised (availability of the stud, specific veterinary equipment and training, rigorous monitoring of the female’s oestrus, speed of transport), taking no more than 48 hours in all. As a consequence, the distance should not be too great.

The results are comparable to those observed in natural mating, although successive manipulations may reduce the vitality of the spermatozoa.

Insemination with defrosted frozen semen

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A team of veterinarians under the leadership of Dr Seager was the first to successfully produce a litter of puppies using defrosted frozen semen in Texas in 1973. The semen is taken in the same way as above. The quality and number of spermatozoa are strictly checked to ensure the semen contains at least 150 million mobile spermatozoa and no more than 30% abnormal forms. The semen is then diluted in a cryoprotective agent, packed in identified straws and preserved in receptacles immersed in liquid nitrogen at -196°C for an unlimited duration.

These straws cannot be used without the consent of the stud’s owner, who can agree a price with the female’s owner based on demand. The sperm bank is simply a service provider in these transactions.

It is better to take advantage of the stud’s maximum vitality period to freeze semen, rather than waiting for old age, the threat of disease or of therapeutic castration to make use of it.

The dog breeding rules of some countries do not allow the recognition of puppies born as a result of artificial insemination with defrosted frozen semen. These authorities refuse to register such puppies in their stud book or issue a pedigree certificate. Despite that, this technique does have many advantages:

• It enables gene exchanges between two countries separated by quarantine rules or a large distance.

• It enables the unlimited preservation of the genes of good studs and use of their semen even if they are otherwise unavailable or dead.

• It enables backtracking when genetic selection by a breed club leads to genetic dead ends. For example, the introduction of semen from less brachycephalic studs could help to correct the sometimes excessively squashed faces often seen in modern-day Bulldogs and thus reduce the incidence of dystocia.

• It enables some breeds close to complete disappearance to be saved.

Diagnosing pregnancy

© Diffomédia/Royal Canin

Fertilisation of an ovum by a spermatozoon results in the formation of an egg, which migrates and divides a number of times before implanting itself in the mucosa of the uterus. On average, this implantation only occurs 17 days after fertilisation and results in the formation of embryonic vesicles, which cannot be seen by ultrasound until week three (18 days at the earliest).

From week three, meticulous palpation of the abdomen may sometimes detect the uterus, provided the female is not too fat and the abdominal muscles are relaxed. Between week five and six of gestation the diameter of the uterus will be about the same as an intestinal loop, which will make it difficult to distinguish between a pregnant uterus and a full large intestine.

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X-rays will only be worthwhile at the end of gestation when the foetal skeletons have calcified to become radio-opaque (from day 45).

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X-rays will only be worthwhile at the end of gestation when the foetal skeletons have calcified to become radio-opaque (from day 45).

Other techniques that detect changes in behaviour, the heartbeat of the foetuses by auscultation (audible in the first two weeks in some females), changes to blood (speed of sedimentation, haematocrit) or mammary development are too slow or too uncertain to be considered reliable.

At the moment, ultrasound is the best method for early diagnosis of pregnancy, enabling the mating to be registered within four weeks with full certainty as to gestation.

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