Select Page
Home 9 Breeder Education Home 9 Infectious Agents That Affect Fertility/pregnancy

Infectious Agents That Affect Fertility/pregnancy

by Sandra Lemire
submitted with permission by Marj Brooks
with thanks to Kevin & Donna Frizzell of DeSaix St. Bernards for generously allowing us to use many of their superb array of articles

I waited to write this article until I had enough statistics to support my position. If you have lost puppies to the “fading puppy syndrome” or had weak, lethargic pups then I hope this subject will benefit you. If not, you’ve been lucky and someday your luck will run out. It is my sincere hope that my heartache will save others from having to go through what I did. *The Problem* For years I required Brucellosis test before breeding a bitch to my males. I thought I was doing all that I could to protect my dog Not so! One day my sister came running into the room with a sample of a dark green vaginal discharge from her champion bitch who was not due to whelp for 8 more days. I started shaking from head to foot. The green discharge was indicating that a puppy was dead or a placenta detached. We headed to the veterinarians for the caesarean section necessary to save the bitch.

If we had not sectioned the bitch immediately we’d have risked losing her to “toxemia” caused from a dead foetus. I held no hope of saving the pups, only 55 days into whelp. It was a miracle to me that two of the three puppies did survive. They were tube-fed for twenty four hours because the anaesthesia had made them lethargic, but after it had worn off they nursed on their own. They opened their eyes at nineteen and twenty-one days, so there was no doubt they were “preemies”. This event was followed four days later by a second bitch, showing a green discharge twelve days before her due date. Again, a caesarean section, and again, a dead puppy and four live puppies that were too premature to survive. Within twenty four hours all the pups were dead.

Three days later, the bitch herself, died. She had gone toxic and we couldn’t save her but more was still to come. Four more girls were in whelp and each of them carried almost full term but the pups were, in some cases, lethargic and weak. One bitch reabsorbed one pup and delivered one that died within one hour. Another had to be sectioned, had adhesions to her bladder and had to be spayed. The pups died, of course. Within the space of four months I had lost fourteen out of twenty puppies and had three caesarean sections (there three girls had previously free-whelped) and had lost Holly Hobby. Now my veterinarians were not idle. Six different doctors were working on the case. We tested for Brucellosis over and over again, the results always negative. We did bacterial cultures, uterine infections, autopsies, etc. Cultures were sent to the University of California at Davis and four vets took tests and histories for four solid hours. We ran viral cultures and retested everything. My vet bills were hovering around $2,000 since my nightmare began. *Pathogens The cause of all these problems ended up to be two bacteria that were “pathogenic” and highly resistant to all antibiotics except two. Our pathogens were an E-Coli and an Enterococcus Group D (beta hemolytic strep). For those who are unfamiliar with the term “pathogenic”, it is a term that is applied to a bacteria that is able to cause problem or infection to the host. It should be understood that bacteria are everywhere, and that most of them are harmless to their hosts. But sometimes when bacteria are subjected to an antibiotic they develop a tolerance for that antibiotic, particularly if the antibiotic is only used for three or four days and then discontinued. The bacterial growth is temporarily slowed down and the patient seems to be improving and symptoms seem to be diminishing so the person administering the medication stops. The medication was merely slowing down the growth of the bacteria (which is what an antibiotic is designed to do) and as soon as the medication is withdrawn, the bacteria bounces back with new vigor AND tolerance for that particular drug.

The result is that the bacteria is now stronger and a different medication must now be used to fight this bacteria because the first drug is no longer effective. When this pattern is repeated a few times, a “super germ”

Another situation can cause a bacteria to change from to “pathogenic”.

Let’s say Fido has a non-pathogenic bacteria that he is able to live with as a part of his natural environment. I call them “garden-variety germs”. His friend Delilah comes to visit, and she has her own bacteria that might have a few resistances but are not pathogenic to her. Bacteria. A has the ability to take on the characteristics and resistances of B. Then a third dog named Jane enters the scene. Her bacteria C) have a few resistances of their own to other antibiotics. Now “A” can also take on the resistances of B or C or both. So before long, germ A has the “ability” to become pathogenic with resistances to several or many antibiotics. If Fido can deal with these bacteria, then all is well. But if the accumulation of A, B, and C are now a strain on his system and he can’t handle all three at once, or his immune system gets busy fighting some other problem. Then germ A or B might become pathogenic to him, causing a problem. Or possibly the next bitch that is sent to him is unable to fight these bacteria due to the strain of shipping.

Cultures and Sensitivities: If the bacteria is resistant to seven or eight out of the ten tested, then this bacteria has a greater chance of being or becoming pathogenic. It is only considered “pathogenic” if the patient exhibits symptoms of a problem. In the case of breeding bitches, those symptoms may not be apparent until close to whelping and it is too late to control the bacterial growth. Because it is a largely resistant bacteria, it may be difficult to treat, possibly requiring a long period of medication or maybe the use of two runs to control it. Your veterinarian must evaluate the tests and symptoms to determine treatment.

Antibiotic Treatment: As many of you are aware, many vets are against breeders using antibiotics without consulting with them. The reason is that many breeders use an antibiotic for just a short time (3 or 4 days and when the symptoms are subsiding the medication is stopped. Then the bacteria come back stronger and more destructive! When your vet sends you home with medication for 7 to 14 days, he wants this medication given for the prescribed time to avoid problems with “super germs”. It should be remembered that each animal must use it’s own resources to control bacterial growth and that the purpose of an antibiotic is not to “kill” a bacteria but to slow down its growth long enough for the animal’s system to deal with it. During medication, and for a week afterward, you should give yogurt and acidophilus every day in the animals diet. This hopefully, will replace pathogenic bacteria with good bacteria like a bacillus. If you eliminate all bacteria from the vaginal tract you open the door for a yeast infection. Now, yeast infections are not harmful to a pregnancy, at least from the litters we have documented but it is very uncomfortable. When the bacteria that is present during medication is eliminated, it opens the door for what ever opportunistic pathogenic bacteria (sometimes even worse than what you started with) to move into the system. it’s kind of like “rental” property. Something will try to live there. So provide a source of good bacteria if you must medicate.

The LEMIRE System: Females in heat are isolated from the first day that it known they are in season. females in heat are never caged together even if they are “roomies” at other times. I use two and three story cages so there is no contact between cages. If a bitch is to be bred on this cycle she must have a vaginal culture and sensitivity done on about her 4th day of heat. As the tests take about four or five days to run, we have the results back before breeding. No exceptions! even my own dogs are cultured every time.

Sometimes I have my cultures done by a lab tech at an equine clinic as they run the cultures on the premises and I get identification in 24 hours and sensitivities in 48 hours. Males are tested before every breeding. I will only use males who are tested. Brucellosis tests are required (current on that heat). Bitches in heat are kept in a separate room away from all males. Therefore, only the male that is assigned to breed the bitch is in contact with her.

Dogs are never switched from cage to cage. Each cage is germicidally cleaned before and after a visitor. Each visitor is fed separately and any left over food is thrown away. All dishes and bedding are washed in bleach water.

Known Pathogens: The following list does not include obscure pathogens. have included the most common that affect the bitch or whelps. After the name we will indicate what the study revealed to us. remember, this only reflects our experience and the experiences of fellow breeders who tested and reported their results back to us.

E. Coli: This bacteria is one of the most pathogenic and can cause fetal death, toxemia, pyometra, and vaginal hemorrhage traditionally this bacteria has been labelled “normal flora” by most labs and physicians (I’m including human medical doctors) when in fact a big percentage of the E. Coli are very dangerous to a pregnancy. It continues to be found as vaginal flora in higher and higher numbers because no one is making any effort to eradicate it from the area. I know of only one occasion where an E. Coli was present during a healthy pregnancy. In most cases, the fetus’ were premature, born dead, placentas detached, bitches toxic, miscarriages and missed pregnancies (commonly classified as infertility in bitches) If dog carries an E Coli in his sheath, he will most likely be unable to produce many live puppies. If he continues to carry E Coli in his sheath for a long time, it can render him permanently sterile. E. Coli has the ability to invade the uterus during pregnancy which used to be credited to brucellosis alone.

Pseudomonas: I accept that this bacteria is found in the environment routinely but when a culture shows it in a vaginal flora, it is useless to even breed the bitch. In most cases it ends up being untreatable with medication, since this pseudomonas is extremely resistant. In the five cases I have seen with this bacteria, not one live puppy issued from its presence. I’ve tried treating with sensitive drugs gradually in double and triple doses for two full weeks, iv meds, or ten days, long term oral meds for five weeks and only once was I able to even get rid of it.

Beta Haemolytic Staph-Aureus: This bacteria is more subtle in that, in eighty percent of the cases, it is not dangerous. Even when it is a pathogen, it usually attacks the puppies after birth. The dam is usually mature enough to have developed a resistance to it. The puppies can’t fight it do they, one by one, stop nursing, dehydrate, and fade away. This is commonly called the “fading puppy syndrome”. The puppies are exposed at the time of birth through the naval cord, and mother’s licking. If the bitch is carrying this bacteria at the time of breeding, she may not become pregnant at all.

Coryne Bacterium: This is, again, one of the most pathogenic. It can cause puppies to die in the womb and cause severe infection in the bitch. Males become infected from breeding a bitch who has it. Very dangerous.

Beta Haemolytic Strep : This bacteria is very contagious and if it is present at the time of the breeding, in many cases the bitch doesn’t take. It can render a male sterile when carried in the sheath. If it is picked up after the pregnancy has settled in, the puppies can be born dead, dying and or die even months later. It’s as though the strep settles in different locations in each puppy and may kill them much later depending on the organ it attacks. I have noticed that uterine inertia seems to happen when beta step is present. I associate it with muscle stiffness and inability to contract similar to strep throat making it difficult to swallow.

Lysteria: This one causes spontaneous abortions and we have seen it three times. In the two cases where it was not treated, the puppies died and one bitch died. In the case where the bitch was treated in whelp, the puppies were born healthy and have done well.

Haemophilus Influenza: This bacteria, if not treated with meds is always fatal to the puppies, or at least has been in the cases we’ve seen. This bacteria is the same one that causes spinal meningitis in human children so it obviously is deadly to several species.

Proteus: Again, this is a bad pathogen. If I hear of a bitch aborting green slime at about three or four weeks into whelp, I’m not surprised when a proteus shows up. Again I’ve never seen a healthy pup delivered in the presence of this bacteria.

Klebsiella Pneumonia: Vaginal infections.

Shigella: Infertility and infections.


Jeanette L. Floss, DVM, MS, and David K. Hardin, DVM
College of Veterinary Medicine, University of Missouri-Columbia

Abortion is defined as the expulsion before full term of a conceptus that is incapable of independent life. Abortion is uncommon in the bitch, but when it does occur, owners should be aware of the treatment options and the prognosis for future fertility.

Establishing and maintaining pregnancy is dependent on many biological interactions between the embryo or fetus and the pregnant female. For approximately 12 days after fertilization, free-floating embryos are dependent on the fluid environment within the uterus for development. If this environment is inhospitable (due to inflammation, hormonal imbalances, etc.), embryos may not survive.

Death of embryos during this period often goes unnoticed because the embryos are resorbed before pregnancy has been detected. Most embryonic losses occur during this period and at implantation, when attachment to the uterus first takes place. These losses are collectively referred to as early embryonic deaths (EED).

After implantation, embryos depend almost entirely on the dam and will not survive if she is unable to adjust to the physical requirements and demands of pregnancy. Factors that lower the odds for survival include fetal or maternal abnormalities, nutritional deficiencies, environmental stresses or infectious causes. Abortions occur most commonly because placental function is compromised due to one or more of
these reasons. Several possible non-infectious and infectious causes of EED and abortion are listed in Tables 1 and 2.

Table 1
Non-infectious conditions associated with loss of pregnancy in the bitch.

Embryonic/fetal defects These and related conditions have been associated with an increased incidence of early miscarriage in women. In the bitch, these could result in early embryonic death and infertility.
Aged gametes Breeding at inappropriate times may lead to aged eggs or sperm cells that have reduced fertility and may lead to abnormal development and death.
Chromosomal defects Defects in the genetic makeup may be incompatible with embryo survival.
Developmental defects Abnormal development of organ systems may not be compatible with fetal survival, leading to death and resorption or abortion.
Maternal environmental stresses These conditions often produce an adverse uterine environment that is incompatible with fetal development. Fetal death may occur at any stage of pregnancy, resulting in abortion.
Hypothyroidism Associated with increased danger of miscarriage in women. Lower than normal levels of circulating thyroid hormone may cause infertility in the bitch.
Hypoluteoidism Deficient progesterone has been suggested as a cause of abortion in several animal species. Progesterone is required for the maintenance of pregnancy in the bitch.
Nutritional deficiencies Energy and vitamin demands increase during pregnancy. If these are deficient, fetal survival may be compromised.
Structural abnormalities Developmental (hypoplasia) or acquired (scar tissue) abnormalities result in compromised placental function that is unable to meet the demands of the growing fetus.
Exposure to drugs/compounds The effects of many drugs/compounds on fetal development are unknown. Dexamethasone, a commonly used anti-inflammatory agent, has been reported to cause intrauterine death and resorption of fetuses when given to pregnant bitches.

Table 2
Infectious conditions associated with loss of pregnancy in the bitch.

Maternal environmental stresses Infectious agents gain access to the pregnant uterus via the blood stream or through the cervix. These can cause placental dysfunction leading to fetal death and in some cases may infect fetuses directly.
Brucella canis The most common bacterial cause of abortion in the bitch. Abortion occurs between 45 and 55 days of pregnancy. Infertility follows infection and abortion. Vaginal discharges and aborted fetal tissues are highly infectious to other females.
Escherichia coli, Staphylococcus aureus, Streptococcus spp., other bacterial isolates These are frequently cultured from vaginal discharges or from fetal tissues after abortion. Their role in causing abortion is unknown. May be associated with infertility, persistent vaginal discharge and repeat abortions in older bitches.
b-hemolytic Streptococcus Fetal infection has been reported, resulting in abortion or the birth of weak, nonviable pups.
Mycoplasma and Ureaplasma These are opportunistic organisms normally found in the vaginal canal. In large enough numbers, they may cause infertility, EED, resorbtions, abortion, stillbirths and weak, nonviable pups.
Canine herpes virus Infections in newborn puppies are fatal. Causes vaginitis in the bitch. This virus can cross the placenta and infect puppies, resulting in fetal death, mummification, abortion, premature birth or delivery of weak, nonviable pups.
Canine distemper virus May cause spontaneous abortion with or without fetal infection. Often abortion results from the stress of the clinical disease.
Canine adenovirus (infectious hepatitis) May cause spontaneous abortion with or without fetal infection. Often abortion results from the stress of the clinical disease.
Toxoplasma gondii Protozoal parasite causing mild disease in adult dogs. May be more severe when present with distemper virus, which is known to suppress the immune system. Fetal infection may occur and T. gondii has been found in milk of lactating bitches.
Neospora caninum Recently identified protozoal parasite that resembles T. gondii, can infect brain and spinal cord of developing fetuses or neonates. Newborns have progressive muscular weakness leading to death.

Diagnostic Work – Up:

With any abortion, the bitch should be presented to a veterinarian as soon as possible for a complete physical examination and collection of samples for diagnostic testing. In most cases, these diagnostic procedures will not save the pregnancy, but they will help identify the appropriate supportive medical therapy and the management practices necessary to prevent future abortions.

The attending veterinarian will want to know the breeding history of the bitch, including the breeding dates for this and previous pregnancies, sire(s), previous whelping dates and the results of previous pregnancies (number of puppies, assisted or unassisted delivery, abortion, etc.). The vaccination history of the bitch and the results of previous Brucella canis serology tests should be given also. Any clinical illness and medications given during pregnancy should be noted at this time as well. Type of housing and diet should be recorded. This information will assist the veterinarian in determining appropriate immediate care as well as recommendations for future breedings.

The physical examination will provide information pertaining to general health, nutritional status and the possibility of an endocrine or other disease process. Abdominal palpation and radiographic or ultrasonographic examination will determine if additional fetuses are present in the uterus. Some or all fetuse
s may be aborted, or remaining live fetuses may be born normally at term.

Laboratory diagnostic tests should include a complete blood count, serum chemistry profile, urinalysis, serologic test for B. canis infection and serum thyroid hormone level determination. These tests will require that one or more blood and urine samples be collected and submitted to a diagnostic laboratory. Most test results can be obtained in less than 24 hours. A culture of the anterior vagina or vaginal discharge should be taken to identify any potential bacterial infection and the appropriate antibiotic treatment.

One of the most important but often overlooked diagnostic procedures is the examination of the aborted fetuses and their associated membranes. In some cases, the bitch may consume aborted fetuses before they can be retrieved, but when these fetuses are available, they should be collected in as clean a manner as possible and taken to the veterinarian with the bitch. Brucella canis infection has been reported in humans; therefore, aborted tissues suspected of being infected should be handled with extreme care.

Histopathology and culture of selected fetal tissues may be recommended. If a bacterial cause is suspected, fetal stomach contents may be cultured, because fetuses swallow amniotic fluid as a normal process of pregnancy. These tests often require that samples be sent to a diagnostic laboratory. It may take several days for results to be returned. Chromosome analysis can be performed in the dog if abnormalities are suspected; however, the analysis is not commonly available.

A bitch with a history of a difficult delivery resulting in trauma to the uterus or cervix may have scar tissue development that is incompatible with maintaining subsequent pregnancies. Exploratory surgery may be required to identify abnormal conditions of the ovaries and uterus in some bitches. Excessive scarring of the reproductive tract is often untreatable and correction of developmental uterine defects cannot be advised. Both of these conditions carry a poor prognosis for future pregnancies.


The bitch should be hospitalized to permit close observation, diagnostic evaluation and supportive therapy if needed. Intravenous fluids may be required to help stabilize a severely ill animal. Blood, urine and culture samples should be taken immediately. Antibiotics should be administered if the blood cell analysis and/or rectal temperature are consistent with the presence of infection.

Compounds are available that increase uterine tone and aid in the evacuation of the uterus. These may be given if all of the fetuses have been aborted and if membranes are retained or if there is heavy bleeding from the uterus. The bitch should remain hospitalized while these compounds are administered and monitored with radiography or ultrasonography for complete emptying of the uterus.


Abortion is preventable primarily by maintaining good health prior to and during pregnancy. Females to be bred should have a good vaccination history and a negative B. canis titre.

Supplemental vitamins should not be necessary provided a nutritionally complete commercial dog food is fed during pregnancy. The amount of food fed should be increased gradually throughout pregnancy to accommodate fetal growth. Pregnant females should gain about 30 percent of their non-pregnant weight by the end of pregnancy.

For females with a history of abortion, a thyroid profile should be evaluated and supplemental thyroxine administered if indicated, beginning prior to breeding.

Supplemental progesterone has been shown to maintain pregnancy in cases where low serum levels are suspected. However, this has proven difficult to validate experimentally because levels are known to be highly variable during pregnancy. Under the influence of progesterone, the uterus is more prone to infection. Also, external genitalia of female fetuses may be masculinized by the administration of progesterone during pregnancy. Therefore, supplemental progesterone should be given only after all other possible causes for repeated abortions have been eliminated. The effects of many other drugs on fetal development are unknown; therefore, if medical treatment is required during pregnancy, it should be done with this in mind.

To control infectious causes of abortion, bitches should be vaccinated regularly prior to breeding and managed under strict sanitary conditions. Brucella canis is most prevalent in kennel situations where contact with infective discharges and fetal tissues may result in infection and possible abortion in susceptible females. Infected males may spread the disease to non-infected females at breeding. Breeding kennels should routinely test all animals for B. canis. To date, there is no permanent cure for B. canis infection in the dog. Therefore, infected animals must not be bred again and should be removed from contact with other breeding animals.

Mycoplasma and Ureaplasma have been cultured from the cranial vagina and prepuce of healthy, fertile animals. However, when females are housed in crowded kennels, close contact and environmental conditions can lead to increased numbers of these organisms, resulting in infertility and pregnancy losses. Providing adequate space, a clean environment and separation of individual breeding animals will greatly reduce the risk of abortion resulting from these and other bacterial infections.

Canine herpes virus abortions have been associated with chronic infertility and cannot be effectively treated at present. Affected females should be isolated from susceptible pregnant animals. Viral abortions are most often due to the stress of clinical disease in the bitch. These can be prevented by routine vaccinations. Pregnant females should not be vaccinated with modified-live vaccines, as these could adversely affect fetal survival.

Consulting a veterinarian prior to beginning a breeding program can help establish preventive management practices that will result in the birth of healthy litters.