Canine reproductive
diseases are rare

IN general, dogs rarely have reproductive problems and most pet owners are concerned with preventing reproduction rather than enhancing it. However, for today's serious breeder of purebred dogs, there is an amazing variety of reproductive diseases and problems that can occur. For the veterinarian to treat the problems, a complete history and physical examination, as well a reproductive history and evaluation of the reproductive tract must be performed.

Infertility in the stud dog
When dealing with infertility, both the dog and the bitch must be considered. Ninety percent of infertility is due to poor breeding management, such as breeding at the wrong time or not breeding often enough; additionally, the male could have poor sperm quality. Acquired infertility is very common in the dog - if more than a couple of months have passed since the dog's last litter, he may now be infertile. Illness before, during, or after breeding could explain why the bitch did not conceive; likewise, a fever or other illness can adversely affect semen production and it takes about 60 days for the sperm cells to regenerate after such an onslaught. A breeding soundness examination can be conducted to evaluate the stud dog; it typically includes a general physical examination and an in-depth examination of the external genitalia.

Abnormalities such as severe arthritis or spinal problems may not allow a dog to mount. Hormonal diseases such as Cushing's disease can also reduce fertility. The penis and prepuce should be examined for irregularities, such as a persistent frenulum, growths, or inflammation of the prepuce (posthitis), that may prevent normal intromission. Inflammation of the prostate (prostatitis) may be painful and can prevent the dog from finishing mating or make him appear to have a lowered libido.

White blood cells (WBCs), red blood cells and bacteria from the prostate may damage sperm viability. Also, an infection in the prostate can potentially ascend to cause an infection in the testicles (orchitis). The size of the testicles correlates with the amount of sperm seen on collection of an ejaculate: small, soft testicles are often associated with poor semen quality, greatly enlarged testicles suggest an infection, and lumps in the testicles are suggestive of tumours. Scrotal abnormalities, such as dermatitis, may adversely affect sperm quality.

An ejaculate of semen should be collected and evaluated for colour, volume, total and progressive motility, concentration and shape (morphology), and the total number of normal sperm should be calculated. There are three distinct outcomes of a breeding soundness examination:

1. normal sperm parameters,
2. abnormal sperm parameters, and
3. no sperm seen in the ejaculate.

Volume varies with the amount of prostatic fluid collected but is generally two to 20 ml. Sperm motility should be evaluated immediately, and normal dogs should have 75 to 80 percent progressively motile sperm (ie, sperm that are moving in a forward direction). A sample of the sperm should be prepared for microscopic evaluation. It is important that the shape of the sperm be evaluated so that the total number of normal shaped progressively motile sperm inseminated is known, as only these will fertilise an oocyte or egg.

Sperm concentration (number of sperm/ml) can be determined by using a special sperm cell-counting device (called a densimeter) or other methods. The total number of sperm in the ejaculate is calculated by multiplying the concentration by the volume; normal is about 10 x 1O6 sperm/lb of body weight. Therefore a small dog can be expected to produce about 20 x 106 sperm per ejaculate and large dogs about 70 x 106. Infertility is very rare in dogs with normal semen parameters. Management problems and bitch infertility should be considered when sperm findings are normal.

If abnormal sperm parameters are found, the dog should be re-cheeked in two to three months to see if the problem is transient. The veterinarian should be informed of any recent illness and any medications (especially anabolic steroids) that the dog has received. Although the actual cause for abnormal sperm parameters is often never found, possible causes, including inflammation of the scrotum, testicular neoplasia, trauma and brucellosis, should always be ruled out. Inflammation of the scrotum can cause a high scrotal temperature that is deleterious to sperm production. An ultrasound of the testicles can be performed to evaluate for testicular neoplasia, as some tumours of the testicle are not palpable. This problem can be treated - a unilateral castration of the affected testicle often restores normal sperm parameters.

If no inciting cause of the sperm abnormalities can be found, the case becomes very frustrating for both the owner and the veterinarian. The absence of sperm in the ejaculate (azoospermia) can have three possible causes:

1. the dog's testicles are not making sperm,
2. the testicles are making sperm, but the sperm cannot get out because the epididymides are blocked, and
3. the testicles are making sperm (which can get out), but a complete ejaculate was not collected.

When there are no sperm in the ejaculate the fluid can be tested for alkaline phosphatase, which is made by the epididymides. A high level of alkaline phosphatase indicates that epididymal fluid was collected. If epididymal fluid was collected and there are no sperm, it is likely that the testicles are not producing sperm. A low level of alkaline phosphatase indicates that the epididymis is blocked or that a complete ejaculate was not obtained. In this case, repeated samples should be collected and an oestrus bitch can be used as a teaser to obtain an ejaculate. A careful palpation and ultrasonography of the epididymides should be performed to detect any abnormalities. If the azoospermia persists, a testicular biopsy can determine whether the testicles are producing sperm; however, this procedure is rarely performed. The biopsy procedure itself may severely damage the testes, and it does not matter whether the testes are producing no sperm or sperm are being produced but cannot get out - neither condition is treatable.

Infertility in the bitch
The most important aspect of evaluating infertility in the bitch is the history. The main purpose of the history is to ascertain if there is a problem with cyclicity, management, or the stud dog or if the apparent infertility is actual pregnancy loss. There are basically two types of bitches: those that cycle normally and those that do not.

The bitch with normal cycles
Bitches that cycle normally generally have a six to 10-month inter-oestrus interval. The quality of the breeder's history depends on the quality of the breeder's records. Most breeders have a pretty good idea of what is going on, but it often takes careful questioning to bring it out in an orderly, understandable manner. The purpose of the veterinarian's questions should be to find out whether the bitch was bred at the right time. A general physical examination of the bitch, an examination of the vulva, and a digital examination of the vestibule and caudal vagina should be performed.

Vestibular strictures may prevent normal intromission by the penis and cause an outside tie (ie, when the bulbus glandis engorges before entering the vagina and is thus too large to fit through the vulva) or may cause the bitch so much pain that she will not allow breeding. Vaginal anomalies including a persistent septum (a band of tissue dividing the vagina into two parts), segmental aplasia (a missing portion of the vagina), or a persistent hymen may be present. Such problems can sometimes be surgically corrected. Although not of much importance themselves, the presence of abnormalities in the vulva, vestibule, or vagina may suggest irregularities in the remainder of the reproductive tract.

Exploratory abdominal surgery (laparotomy) or contrast radiography may help assess abnormalities in the more cranial portions of the reproductive tract (eg., cervix, uterus, oviducts, ovaries). Vaginal prolapse may preclude normal penetration by the male. Vaginal hypertrophy (enlargement of the vaginal floor) may occur during oestrus and interfere with natural mating.

Aerobic bacteria may be cultured from the vagina of all normal bitches, and mycoplasma is present in 80 percent of normal, fertile bitches. Any organism cultured in the absence of clinical signs is considered a normal inhabitant of the vagina.

Mycoplasma is a normal inhabitant in 70 percent to 80 percent of dogs and bitches, and treating a perceived "infection" in an infertile dog does not restore fertility. If the physical examination is normal and a management problem cannot be detected, the veterinarian may wish to follow the bitch through a complete cycle to ensure that she is cycling normally, has a normal rise in progesterone and normal luteal phase (evaluated by testing progesterone levels throughout the two months after the heat cycle), and, most importantly, was bred at the optimum time.

Remember, the potential fertility of a bitch cannot be evaluated unless she is bred to a fertile male. Was the male impregnating other bitches that were bred around the same time as the one that failed to conceive? When was the stud dog's last litter? Was the stud dog sick in the two months prior to breeding this bitch? If a solid history of the male cannot be obtained, a breeding soundness examination should be performed on the bitch. Management problems should be corrected, and an optimum breeding management programme should be outlined with the help of a veterinarian. As mentioned, the best follow-up is to have a veterinarian who is interested in canine reproduction follow the bitch through the next heat cycle. This, along with serial progesterone levels and serial vaginal cytogy, will pinpoint the optimum time to breed the bitch.

The quality of the breeding can be important. A natural tie is the best guarantee of a successful semination. In cases of an outside tie the tip of the penis can be held tightly by the handler just behind the glans and a fairly normal ejaculation should occur. Conception rates can be normal with outside ties. Artificial insemination is only as good as the person performing it.

Although the technique is very simple in dogs, once the sperm is outside the dog, it is exposed to many insults including mishandling, toxins, cold or heat shock, and bad insemination techniques. Breeders should determine how experienced the inseminator is and what his or her pregnancy rate is; a good inseminator should have a pregnancy rate approaching that of natural breeding. Conception rates with chilled extended semen and frozen semen remain disappointingly low, and these are not recommended for bitches with infertility problems. If a bitch was bred with one of these methods and did not conceive, breeding should be tried again using fresh semen before suspecting that she has a fertility problem.

A possible, but not well-documented cause of conception failure and/or pregnancy loss is sub-clinical uterine infection. Signs include vulvar discharge during diestrus and apparent embryo loss after a positive ultra sound. Treatment can include prophylactic antibiotics on the next heat cycle until whelping. These bitches should have ultrasonograms to detect pregnancy 30 days after the last breeding.

The bitch with abnormal cycles
The bitch with abnormal oestrous cycles may have no cycles, long inter-oestrous interval or short inter-oestrous intervals. A bitch that is less than two years old and not cycling may not have reached puberty yet. Some large-breed bitches do not have their first heat cycle until they are two-and-a-half years of age or older.

Some medications such as progesterone, androgens, and glucocorticoids can interfere with cyclicity. A karyotype should be performed on any bitch over three years of age that has not had a cycle to determine if there is a chromosomal abnormality. If there is an abnormal chromosome, there is no hope for fertility. Because some bitches do not show signs of heat that are recognisable to an owner, especially if no male dog is present, progesterone concentration should be determined. A high level indicates that she has been in heat within the last two months. The test should be repeated approximately two-and-a-half months later, by which time the progesterone level should have returned to baseline.

If progesterone is still high in the second sample, possible ovarian abnormalities (eg, a luteal cyst or ovarian tumor) may be present, this can be evaluated by ultrasound or laparotomy. Luteal cysts are rare but could respond to prostaglandin therapy. Unilateral and non-metastatic ovarian tumors can be removed, which could possibly restore fertility. Cushing's disease may cause elevated progesterone levels and should have been tested for in the bitch with persistently high progesterone levels. A link between thyroid function and infertility is not clear, although there were reproductive problems in one kennel of hypothyroid dogs. Thyroid function can be tested - if the bitch is found to be hypothyroid, thyroid medication can be administered. However, if a bitch's infertility is due to hypothyroidism, she should not be used for breeding.

If thyroid levels are normal, the veterinarian should have blood samples evaluated for luteinising hormone (LH) and follicle-stimulating hormone (FSH) levels. If the levels are high the bitch is not receiving feedback from the ovaries, which indicates gonadal dysgenesis or primary ovarian failure.

Long inter-oestrous intervals (ie, over 10 months) may be a normal variation, especially in larger and/or older bitches. There is no good way to bring a bitch into a fertile heat cycle, so the breeder will have to wait for her to cycle. Thyroid function can be checked as for the bitch with no cycles. Short inter-oestrous intervals may lead to infertility because the uterus does not have enough time to return to its normal size and shape after whelping or the previous heat cycle.

The inter-oestrous interval can be lengthened by medication, which should begin a few weeks before she is expected to come into heat. That expected heat cycle will not occur and the bitch should come into a heat four to six months after the end of the treatment. The bitch can be bred on this cycle and may be fertile if shortened inter-oestrous intervals were her only problem. Short interoestrous intervals seem to relate to inadequate luteal phase. The progesterone level continues to rise after ovulation but drops to baseline after one month to six weeks. The normal luteal phase is 60 to 70 days. An inadequate luteal phase is documented by serial progesterone samples every few weeks throughout pregnancy. If documented luteal insufficiency exists, the bitch can be supplemented with progesterone in oil for 56 to 58 days after ovulation. Progesterone must be discontinued at that time to allow normal whelping.

Split heats occur when a bitch grows follicles on her ovaries and experiences the signs of pro-oestrus (swollen vulva, vulvar bleeding, attractiveness to males) but does not progress into oestrus and does not ovulate. The bitch's follicles will usually regress, and then she will come into a complete heat cycle with ovulation anywhere from two to 12 weeks later. Split heats are most common in a young bitch, especially at her first season, and are not considered to be associated with infertility when bred on the cycle in which ovulation occurs. Split heats must be differentiated from short inter-oestrous intervals between two true heat cycles. A vaginal smear will show red blood cells and intermediate and superficial cells as would be expected during pro-oestrus but in a split heat will not progress into an oestrus smear.

Periparturient diseases
Periparturient diseases can be seen prior to, at the time as, and soon after whelping. One of the most common problems reported by breeders is false pregnancy. This condition occurs during the luteal phase (diestrus), which is the progesterone-dominated phase that all bitches experience after an oestrus or a heat cycle. Because of the similarity between the hormonal profiles of pregnant and non-pregnant bitches, many of the changes seen in the pregnant bitch are also seen in the non-pregnant bitch. These physical changes include mammary gland growth, abdominal enlargement and lethargy. In addition, if the progesterone level fails rapidly in the non-pregnant bitch, as would occur at whelping, the behaviours associated with parturition (nesting, lactating, "adopting" objects and trying to nurse them) may be seen. Generally, no treatment is needed or recommended; however, when necessary, such as in cases of destructive nesting behaviours, medication may be used.

Abortion or resorptions can be caused by many different factors; even when the aborted foetuses and/or placentas are available for evaluation, the exact cause of pregnancy failure may not be understood. It is extremely difficult to accurately assess the number of abortions or resorptions because there is no way to confirm pregnancy during the first four weeks of gestation. Also, ultrasonography or radiography to detect pregnancy is not performed in most bitches unless there is a problem or suspected problem. In general, the causes of abortion/resorption can be divided into foetal defects, maternal problems, infectious diseases, and endocrine or hormonal causes. Any defect in foetal development that is not compatible with life will result in abortion/resorption. Defects in the foetus can be caused by chromosomal abnormalities or major organ defects or can result from the use of medications that cause defects in the developing embryos (called teratogens).

A wide variety of commonly used medications and chemicals can cause defects in the foetus, especially in early pregnancy. Canine herpes virus (CHV), a common cause of neonatal death, is also thought to be involved in infertility, abortion, and stillbirth in the bitch. Genital vesicles can be present in the non-pregnant bitch. Up to 80 percent of bitches will be seropositive for CHV, but very few have reprodutive problems. Reproductive problems are seen only when a naive bitch is infected during the last three weeks of pregnancy or when pups are infected during the first three weeks of life.

The transmission of CHV may be venereal transplacental, or respiratory or by vaginal contact during birth. In pups, CHV causes a fatal disease characterised by generalised necrosis and bleeding. The disease is usually mild or subclinical in adults and consists of conjunctivitis, a serous mucopuruient ocular and/or nasal discharge, and vaginal lesions that start as vesicles early in the course of the disease but then become circular pock-like. Genital lesions usually disappear shortly after infection but may reappear at the onset of the next pro-oestrus.

A CHV-infected bitch may have dead and/mummified pups in the same litter as live pups. The placenta from a bitch infected with CHV is typically under-developed and has white-gray areas that range in size from very small to that of a grain of rice. Diagnosis of CHV is based on virus isolation, which requires fastidious sampling and culture techniques; a negative result may be due to inadequate technique rather than a truly negative sample. No vaccine is available; the only recommendation is to expose naive bitches prior to breeding.
Other, less common causes of canine abortion include toxoma gondii, mycoplasma, and ureaplasma infections. Toxoplasmosis is a rare cause of abortion. Cats are the definitive host; and dogs become infected by ingesting infected cat faeces or infected meat. Diagnosis is made by two serum samples obtained three weeks apart. A fourfold increase in serum titer levels indicates toxoplasmosis infection. Prevention is accomplished by preventing exposure to cat faeces and raw meat.

Mycoplasma and ureaplasma, which are normal organisms in the canine vagina, have been implicated in infertility, resorption, abortion, stillbirths, and neonatal death. It is difficult to establish a cause-and-effect relationship because 80 percent of normal bitches have a positive vaginal culture for mycoplasma. Just because mycoplasma can be isolated from a bitch that aborted does not mean that mycoplasma caused the abortion. Because the organism is a normal inhabitant of the vagina, diagnosis of mycoplasma abortion is, at best, tentative. Mycoplasma and ureaplasma-induced abortions are rare.

Treatment involves the use of antibiotics for 10 to 14 days. Non-infectious causes of abortion include inadequate luteal function, inadequate diet, and inappropriate administration of medications. Inadequate luteal function or a low progesterone level has not been well documented.

Bitches with a history of repeated embryonic resorption, as detected by ultrasonography, have been found to have low progesterone levels in the second month of gestation. Bitches can be tested for progesterone concentration, and those with low levels can be supplemented with progesterone in oil until 56 to 58 days after ovulation. Bitches require carbohydrates in late gestation. Those fed a diet deficient in carbohydrates will have an increased incidence of stillbirths.

All drugs should be avoided during pregnancy if possible. Treatment of a bitch with impending abortion is limited to restricting activity, administering antibiotics, and making sure the progesterone level is adequate. A bitch that has recently aborted should be evaluated for signs of systemic disease and pyometra. Retained and dead foetuses can be diagnosed via ultrasonography and/or radiography. If retained pups are present, the treatment options are spaying or opening the uterus and removing the dead foetuses (uterotomy).

Cystic endometrial hyperplasia/pyometra complex
Pyometra is actually a hormonal disease in the bitch; although a bacterial infection is involved, it is the presence of progesterone and its effects on the uterus during diestrus that allow the infection to occur. Pyometra occurs most often during dioestrus, the 60-day to 70-day period after the heat cycle when the uterus is under the influence of progesterone. A function of progesterone is to quiet the muscular activity of the uterus and close the cervix. Cystic endometrial hyperplasia (CEH) usually precedes the development of pyometra in older bitches, although pyometra can be seen in bitches of any age. Under the influence of progesterone, the lining of the uterus becomes thicker with cystic areas due to an increase in size and activity of the endometrial glands, which exhibit secretory activity. The use of synthetic progestogens have many effects that are similar to those of endogenous progesterone and can therefore contribute to the development of CEH. These combined actions of progesterone allow for an accumulation of secretions that permit bacterial overgrowth.

Diagnosis of pyometra is made when the bitch has fluid in the uterus (demonstrated by ultrasonography) and an increased WBC count. There are two types of CEH-pyometra - open or closed cervix - and each has its own treatment. In bitches with open-cervix pyometra there is a purulent or bloody vulvar discharge, usually first noted about six weeks after heat. Other clinical signs include lethargy, depression, anorexia, increased thirst, increased urination, vomiting and diarrhoea. Most bitches with open cervix pyometra are otherwise relatively healthy because the infection is draining out of the uterus. These bitches are candidates for medical treatment, which consists of prostaglandin therapy and possibly the use of antiprolactin agents.

The bitch with closed-cervix pyometra is often quite ill compared to the one with open-cervix pyometra. This is because the infection is not able to drain from the uterus. Clinical signs are similar to those of open-cervix pyometra but may include weight loss and abdominal enlargement, and are often more extreme. Severe diarrhoea, which is associated with progressive septicemia, can result in dehydration, shock, coma and death if not treated aggressively. Spaying is the treatment of choice for closed-cervix pyometra - the uterus is the source of infection and must be removed as soon as possible.

Medical management of pyometra involves prostaglandins, even though they are not approved for use in the dog, as low-dose prostaglandin therapy has been effective in eliminating fluid from the uterus. Antibiotics should also be used. The bitch is treated with prostaglandin and two weeks later re-evaluated for fluid in the uterus (which should have decreased markedly) and VMC count (which should be significantly lower); additionally, there should be no vulvar discharge. Bitches treated with prostaglandin therapy should be bred at the next heat cycle.
In one study of 42 bitches treated medically for open-cervix pyometra, 39 had complete resolution and 37 of these successfully whelped at the next heat cycle.

Microscopic section of a normal dioestrus uterus. Note the presence of small glands in the endometrium (arrows)

Mild cystic endometrial hyperplasia with the glands (arrows) enlarged

Cross-section of a uterus showing severe cystic endometrial hyperplasia. Note the thickening of the wall of the uterus and the many fluid-filled (cystic) structures within the walls of the uterus

Postpartum problems
Eclampsia (hypocalcemia or puerperal tetany) is an acute, life-threatening disease caused by low calcium levels. It is most often seen in small to medium-sized bitches at peak lactation, although it can be seen in late pregnancy through 45 days postpartum. The initial signs may be subtle and vague, such as restlessness, nervousness, pacing, panting, whining, loss of maternal behaviour, irritability, increased salivation, stiff gait, inco-ordination, muscle tremors, and pain. The bitch can progress quickly (minutes to hours) to tetany and seizures. The immediate goal is to return the serum calcium level to normal by slow intravenous administration of 10 percent calcium gluconate.

A response should be seen within 15 minutes. Calcium supplements should not be used during pregnancy as they may increase the incidence of hypocalcemia. A low calcium level during pregnancy allows the body to adapt to the gradually increasing demands for calcium by the developing pups so that the mechanism for calcium removal from body stores in the bones is already in place when the demand for calcium increases dramatically during lactation.

Conversely, a high calcium level during gestation does not allow the body to draw on stored calcium; thus the bitch is unable to meet a sudden need to remove calcium from her bones and her blood calcium level can become dangerously low, leading to the development of eclampsia. Also, diets high in legumes (soy beans) may tie up calcium and should therefore be avoided in the lactating bitch. The mammary glands are highly modified skin glands located in two parallel rows along the ventral chest and abdomen.

Dogs have four to six (usually five) pairs of glands. It is not uncommon to see a missing nipple or pair or asymmetrically placed nipple. Milk is produced from alveoli (secretory cells) which are arranged in clusters called lobules. The milk fills the alveoli and then is drained from the lobules through small ducts. A crust of eight to 22 large ducts drains to the outside of each teat.

Mastitis is an infection of the mammary gland that usually occurs within the first week of postparum. The bitch may be ill, have a fever, decreased appetite and depression, and may not allow the pups to nurse. The affected gland is usually warm, firm, red, and painful. Milk from the infected gland is abnormal. Antibiotic treatment is based on culture and sensitivity of the affected gland. If necessary, the pups may be allowed to nurse but should be monitored for weight gain. If the pups develop diarrhoea or fail to thrive, they should be removed from the dam and hand raised. If the pups are nursing, the veterinarian should be certain to use antibiotics that do not affect them. Occasionally, the mammary glands form abscesses that need to be surgically drained.

Agalactia, or lack of milk, is rare in the bitch. There is no good treatment and pups need to be hand fed or fostered to another bitch. Sometimes a nervous bitch will not allow nursing immediately postpartum; reassurance from the owner may be all that she needs, or tranquillisers may be useful.

This article is reproduced with the kind permission of Kal Kan foods, Vernon, CA, USA.