Dog Breeding by LowchensAustralia.com

Definition

The causes of abortions are not well known and not sufficiently dealt with in veterinary medicine due to incomplete data, uncertain aetiological agents and modes of transmission, possible microbial synergies, etc. 

Both breeders and veterinarians should:

• Apply strict sanitary measures: the period following abortions presents a major risk of spreading the infectious agents involved to rest of the breeding facility; 
  

• Adopt a methodical diagnostic approach
  

• Carefully choose and evaluate the complementary examinations to be carried out. 
  

• Abortions do not systematically occur in bitches contaminated by an infectious agent, whatever it is. A bitch that has aborted one or more times can later give birth in normal conditions (immunization).

Main causes

A multitude of factors may cause abortions in pregnant bitches. In breeding facilities, infectious causes rarely lead exclusively to abortions, except in specific cases (e.g. brucellosis). In addition, other disorders of the reproductive cycle (infertility, stillbirths, neonatal mortality) and/or other symptoms (e.g. digestive or respiratory disorders) in the breeding facility. It should be underlined that when abortion occurs before 40-45 days of pregnancy, the latter generally goes unnoticed clinically (in utero foetal resorption). Thus, many pregnancy terminations appear as apparent infertility.

Bacterial causes

Non-specific bacteria

• Most frequent occurrences: bacteria originating in the genital tract, responsible for the onset of chronic endometritis (saprophyte bacteria of the vagina multiply, leading to immunosuppression or untimely antibiotic prevention), from food (Salmonellae), mating, sniffing of abortion products or ingestion of contaminated foetal membranes. Several potentially pathogenic bacteria may however be identified in the bitch's genital system without causing abortion. 
  

• Abortions caused by vaginal bacteria becoming pathogenic due to excessive multiplication beyond the pathogenicity threshold: gram-negative (E. coli, Proteus sp.) or gram-positive (Staphylococcus sp., Streptococcus sp.) bacteria. 
  

• Pasteurellosis (Pasteurella multocida) (causing late-term abortions, frequently associated with mastitis). 
  

• Bovine brucellosis (dogs can be a potential reservoir of Brucella abortus). 
  

• Salmonellosis. 
  

• Mycoplasmomis (Ureaplasma sp.). 
  

• Campylobacteriosis (Campylobacter jejuni). 
  

• Pseudomonas sp. abortions. 
  

• Q fever (Coxiella burnetti): suspected but not proven. 
  

• Chlamydiosis, haematobartonellosis: not proven (sometimes causes abortions in cats).

Specific bacteria

•  Brucella canis infection. 

Viral causes

• Canine herpesvirus infection (although abortion is not the most prominent clinical sign of this disease). 
  

• Canine distemper (rare; mainly in experimental conditions).

Parasitic causes

• Toxoplasmosis (Toxoplasma gondii). 
  

• Neosporosis (suspected).

Hormonal causes

• Luteal insufficiency: drop of progesterone concentration during early pregnancy, more frequent in certain breeds (e.g. German Shepherd, Rottweiler, Newfound-land, or Bernese Mountain Cattle dogs). 
  

• Hypothyroidism: well known cause of abortion in women, but poorly documented in bitches. 
  

• Hypercorticism. 
  

• Diabetes mellitus. 
  

• Iatrogenic causes. 
  

• Untimely administration of corticoids, oestrogens, antimitotics, prostaglandins, prolactin inhibitors (cabergoline) or antiprogestins (aglepristone). 

Chromosomal or genetic abnormalities

Chromosomal or genetic abnormalities are well documented in women but less so in bitches (Reminder: normal karyotype: 2n = 78, XX or 78, XY). Role of gamete ageing (bitches used for breeding purposes: abnormalities increase with age).

• Monosomy X (2n-X) (karyotype: 77, XO). 
  

• Triploidy (3n) (karyotype: 77, XXX). 
  

• Translocations, mosaicism, etc. 

Dietary causes

• Diet poor in sodium (< 0.03%) during late pregnancy. 
  

• Excessive intake of vitamin A between 15 and 25 days of pregnancy. 
  

• Severe malnutrition in pregnant bitches: rarely abortive but often resulting in the birth of weak puppies. 

Other causes

• "Mechanical" uterine causes: endometriosis, glandulocystic hyperplasia, scars or adhesions resulting from former caesarean sections (hysterotomy). 
  

• Toxic origin (not well known). 
  

• Trauma (kicks, fights). 
  

• Inappropriate general anaesthesia of pregnant bitches (increase the level of oxygen in anaesthesia gas).
  

• Vaccination with attenuated live vaccines (no risk according to manufacturers).

Diagnosis

Case history

Examination of case history is the first and essential stage of diagnosis: 

• Age and breed, 
  

• Medical history 
  

• Genital history (number of litters and health of newborn litters). 
  

• Prolificacy. 
  

• Frequency of oestrus. 
  

• Previous examinations: early diagnosis of pregnancy (palpation, ultrasound, relaxin assay), vaginal smears, hormonal monitoring of pregnancy (progesterone).

Clinical examination:

• Clinical appearance of vulvar discharges (since bitches often ingest aborted foetuses, which then are not all found after abortion). 
  

• Early abortion (blood or serohaemorrhagic discharge). 
  

• Late abortion (greenish-brown discharges: uteroverdin (placental pigment)). 
  

• Infectious complications (purulent discharge). 

Appearance of foetus 

The appearance of foetus is difficult to determine due to rapid autolysis after expulsion.

• Determination of approximate age, where possible (D35: separation of fingers; D40: eyelid attachment, closing of white line, and development of claws; D45: early growth of hair and development of skin pigmentation; D53: body entirely covered in hair).
  

• Presence of malformations.
  

• Good preservation or autolysis of foetus (in cases of brucellosis, the aborted foetus shows advanced autolysis at expulsion).

Appearance of placenta

• Autolysis. 
  

• Underdevelopment (small size as compared to the foetus). 
  

• Signs of placentitis (congestion and/or infectious or haemorrhagic foci). 
  

• Presence of necrotic foci (e.g. canine herpesvirus often causes greyish foci of miliary necrosis).

Clinical examination of the bitch

• General clinical examination. 
  

• Gynaecological examination (warning: it is recommended to wear gloves due to the risk of zoonosis). 
  

• Vulva and vestibule: presence of papules or blisters (herpesvirus). 
  

• Vagina: vaginal smear (vaginitis: abundance of polynuclear neutrophils; metrorrhagia: abundance of red blood cells). 
  

• Uterus: palpation, ultrasound and/or radiography (presence of non-expulsed foetuses, possibly still alive; partial abortions (possible in bitches); associated pyometra, etc.).

Recommended course of action

Urgent sanitary measures

• Isolation of the bitch from the rest of the animals. 
  

• Careful cleaning and disinfection of the area when the abortion occurred. 
  

• Management of aborted foetuses (wearing gloves): immediate post-mortem examination (take precautions in order to avoid contamination by exogenic micro-organisms i.e. disinfection and availability of a Bunsen burner); collection of 2 samples from the spleen, liver and lungs i.e. one for bacteriological testing (posted immediately to the laboratory) and the other for histological examination (fixation in 10% formaldehyde). Immediate freezing at –20°C for future examinations. Medical and/or surgical treatment of the bitch, where necessary (pyometra, fever, unnecessary lactation, etc.). 
  

• General precautions in the daily management of the breeding facility (change shoes and/or clothing; wearing overboots; always move in the same direction through the facility, etc.). 

Laboratory examinations

• Endocrinology: Progesterone (and thyroxine, where necessary) assay to be carried out as soon as possible after abortion. This assay is of little diagnostic value since the progesterone level often drops immediately after abortion, even if the latter is not attributable to a hormonal disorder. However, if the progesterone level is very low (< 3 ng/ml), abortion could be have been caused by an early luteal disorder.
  

• Serological testing for bovine and canine brucellosis, canine herpesvirus, chlamydiosis, toxoplasmosis, distemper (septicaemia), Q fever, etc. 
  

• Vaginal bacteriology with (saprophytic bacteria) or without (Mycoplasma, Brucella) transport medium. Collection of swabs from the lower third of the vagina. 
  

• Bacteriological culture of bitch's blood (brucellosis) or blood taken from the heart of an aborted foetus (transport medium required). 
  

• Bacteriological examination of aborted foetus or placenta, often carried out at a later date, after freezing (brucellosis). 
  

• Tests for herpesvirus and distemper virus in the aborted foetus (time-consuming and delicate). 
  

• Histological examination of organs from an aborted foetus, collected and fixed (10% formaldehyde) as soon as possible before autolysis. Test for specific inclusion bodies (herpesvirus, Toxoplasma, etc.). 
  

• Karyotyping of aborted foetuses in case a problem of chromosomal origin is suspected.

Recommended course of action in the medium term

Once the causal agent of the disease or disorder has been identified:

• Examination of other bitches in order to find out how many of them have been infected. 
  

• Specific treatment of contaminated animals or removal from the breeding facility in cases of severe infections (brucellosis). 
  

• Bacteriological and/or serological tests (absence of seroconversion) to make sure of recovery. 
  

• Systematic tests to be carried out during later pregnancies in bitches which have previously aborted: vaginal bacteriology at the time of oestrus, hormonal monitoring of pregnancy in cases of suspicion of luteal insufficiency (progesterone assays twice weekly), as early as possible pregnancy diagnosis (ultrasound at 15-18 days) to detect possible signs of foetal resorption.

Prevention of recurrence

• Vaccination against canine distemper and canine herpesvirus infection. 
  

• Inspection of breeding facilities to decide on the corrective measures to be implemented to improve the sanitary status and/or prevent overpopulation.

Conclusion

Veterinarians confronted with abortive disorders should rapidly take the appropriate course of action in order to prevent the spread of any micro-organism to the whole breeding facility and to identify the causal agent (samples should be collected as soon as possible and in the right conditions). 

Some pathogenic bacterial infections – such as salmonellosis (following ingestion of contaminated food), pasteurellosis (Pasteurella multocida), or Q fever (Coxiella burnetti) causing abortions in cattle – have been suspected of causing reproduction disorders in dogs. The position of chlamydiosis in this respect is not very clear.

Predispositions

The vaginal tract (upper part) of the bitch houses a multitude of bacteria, some of which are listed:

• Escherichia coli +++,

• Streptococcus sp. (including beta-haemolytic Streptococci),

• Staphylococcus sp.,

• Klebsiella sp.,

• Haemophilus canis,

• Proteus sp., 

• Mycoplasma sp.,

• Ureaplasma sp.,

• Bacteroides sp.

Usually, these bacteria are not pathogenic (e.g. beta-haemolytic streptococci are present in 30% of female dogs without any reproduction disorders being reported). However, in immunosuppressed animals (due to stress, another disease, another micro-organism (canine herpesvirus), these bacteria may multiply at such rates that reproduction disorders (infertility, miscarriages, stillbirths, and neonatal mortality) can be observed.

Transmission

• Contamination of adult dogs may occur by the sexual route i.e. possible passage of bacteria from male preputial flora to female vaginal flora, and inversely. 
  

• Contamination of puppies usually occurs at birth or shortly after by sniffing the genital secretions of their mother.

Diagnosis

Presumptive diagnosis of possible vaginitis is based on vaginal smear examination (abundant polynuclear neutrophils) or vaginoscopy. 

Diagnosis based on vaginal culture remains uncertain and delicate:

• Samples should be taken in the lower third of the vaginal tract, in as sterile as possible conditions (protected swabbing). 
  

• Isolation of the micro-organism is valid only if it is present in abundance, pure or in the presence of at most one other micro-organism. Isolation of more than three micro-organisms in a sample means that contamination occurred during sampling or the absence of pathogenic organisms. 
  

• The latter point applies to bacteriological tests carried out in cases of neonatal mortality in puppies or when testing for a micro-organism in the milk in cases of suspected mastitis-metritis syndrome. 
  

• Particular attention should be paid to diagnosis made by human analysis laboratories that identify the micro-organisms frequently observed in women by analogy, which does not apply to bitches.

Treatment

• Antibiotic therapy by the systemic route, according to antibiogram results. Minimum duration of treatment: 2-3 weeks. Antibiotics with good diffusion into the vaginal mucosa include sulphonamide potentiators, macrolides and fluoroquinolones. 
  

• In cases of vaginitis: association of antibiotic therapy with local deep vagina irrigation using with antiseptic solutions or antibiotic ointments (e.g. intramammary ointment for bovines) can be beneficial.

Prevention

• Control of genital hygiene in breeding dogs (detection of balanoposthitis and vaginitis). 
  

• In breeding facilities, systematic prophylactic use of antibiotics should be proscribed since it promotes bacterial resistance.

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. 

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 fetuses 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 hospitalised 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 hospitalised 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 titer. 

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. 

• Pregnancy Termination
• Brucellosis (Canine)
• Canine Abortion
• Have Dogs Tested for Canine Brucellosis Before Breeding
• Stress, Infertility and Herpes Infection
• Canine Pregnancy Failure 
• Canine Brucellosis
• Reproductive Effects of Canine Herpesvirus