Definition

Loss of a fetus because of resorption in early stages or expulsion in later stages of pregnancy.

Pathophysiology

• Direct causes-congenital abnormality, infectious disease, trauma.
• Indirect causes-infectious placentitis, abnormal ovarian function, abnormal uterine environment.

Systems Affected

• Reproductive.
• Any dysfunction of a major body system can adversely affect pregnancy.

Genetics

• No genetic basis for most causes of abortion.
• Lymphocytic hypothyroidism-single-gene recessive trait in borzois.

Incidence/Prevalence

• True incidence unknown.
• Resorption estimated between 11–13%, some estimates up to 30% of at least one resorption.
• Incidence of stillbirth reported as 2.2–4.4%; increases with dystocia up to 22.3%.

Signalment

Signs

Causes

Risk Factors

• Exposure of the brood bitch to carrier animals
• Old age
• Hereditary factors

Differential Diagnosis

• Differentiate infectious from non-infectious causes-B. canis of immediate and zoonotic concern.
• Differentiate resorption from infertility-helped by early diagnosis of pregnancy.
• History of drug use during pregnancy-particularly during the first trimester, or use of drugs (e.g., dexamethasone, prostaglandins, ketoconazole, griseofulvin, doxycycline, tetracycline, dantrolene, among others) known to cause fetal death.
• Vulvar discharges during diestrus-may mimic abortion; evaluate discharge and origin to differentiate uterine from distal reproductive tract disease.
• Necropsy of aborted fetus, stillborn puppies, and placenta(s)-enhances chances of a definitive diagnosis, refrigerate but do not freeze prior to submission.
• History of systemic or endocrine disease-may indicate problems with the maternal environment.

CBC/Biochemistry/Urinalysis

• Usually normal.
• Systemic disease, uterine infection, viral infection, or endocrine abnormalities-may produce changes in CBC, biochemistries, or urinalysis.

Other Laboratory Tests

• Serologic testing-B. canis, canine herpesvirus, and Toxoplasma, Neospora; collect serum as soon as possible after abortion; repeat testing for raising titers for canine herpesvirus, Toxoplasma, Neospora.
• Slide test for B. canis-very sensitive; negative results reliable; prevalence of false positives as high as 60% (D-Tec CB^®, Synbiotics Corp., (800)733-5500);
• PCR for B. canis now available;
• Definitive diagnosis made via culture.
• Tube agglutination test for B. canis-gives titers; titers >1:200 considered positive; titers from 1:50–1:200 considered suspicious.
• Agar gel immunodiffusion test for B. canis-effectively differentiates between false positives and true positives in agglutination tests; detects cytoplasmic and cell surface antigens (Cornell University Animal Health Diagnostic Laboratory, (607)253-3900).
• Baseline T₄ serum concentration (when no infectious agents are identified)-hypothyroidism is a common endocrine disease and has been suggested as a cause for fetal wastage; role in pregnancy loss unclear; subnormal T₄ concentrations indicate need for further testing (see Hypothyroidism).
• Serum progesterone concentration (when no infectious agents are identified)-hypoluteoidism may cause fetal wastage; dogs depend on ovarian progesterone production throughout gestation (minimum of 2 ng/mL required to maintain pregnancy); collect sample and determine as soon as possible after abortion; in subsequent pregnancies, start weekly monitoring at week 3, which may be before pregnancy can be documented with ultrasound; start biweekly sampling around the gestational age of previous loss. Pregnancy loss typically occurs during the seventh week of gestation (see Premature Labor).
• Vaginal culture-B. canis with positive serologic test; Mycoplasma, Ureaplasma, other bacterial agents; all except B. canis can be normal flora, therefore diagnosis difficult from vaginal cultures alone; Salmonella associated with systemic illness in the bitch.

Imaging

• Radiography-identifies fetal structures after 45 days of gestation; earlier, can determine uterine enlargement but cannot assess uterine contents.
• Ultrasonography-identifies uterine size and contents; assesses fluid and its consistency; assesses fetal remains or fetal viability by noting heartbeats (normal, >200 bpm; stress, <150 or >280 bpm).

Diagnostic Procedures

• Vaginoscopy-identify source of vulvar discharges and vaginal lesions; use a scope of sufficient length (16–20 cm) to examine the entire length of the vagina.
• Cytologic examination and bacterial culture-vagina may reveal an inflammatory process (e.g., uterine infection); technique for culture: use a guarded swab culture instrument to ensure an anterior sample (distal reproductive tract is normally heavily contaminated with bacteria), or collection of secretions via transcervical catheterization.

Pathologic Findings

Histopathologic examination and culture of fetal and placental tissue-may reveal infectious organisms; tissue culture, particularly of stomach contents, to identify infectious bacterial organisms.

Appropriate Health Care

• Most bitches should be confined and isolated pending diagnosis.
• Hospitalization of infectious patients preferred.
• B. canis- highly infective to dogs; shed in high numbers during abortion; suspected cases should be isolated.
• Outpatient medical management-medically stable patients with non-infectious causes of pregnancy loss, endocrinopathies, or endometrial disease.
• Partial abortion-may attempt to salvage the live fetuses; administer antibiotics if a bacterial component is identified.

Nursing Care

Dehydration-use replacement fluids, supplemented with electrolytes if imbalances are identified by serum biochemistries.

Activity

Partial abortion-cage rest generally recommended, although the positive effect on reducing further abortion is unknown.

Diet

No special dietary considerations for uncomplicated cases

Client Education

• Critical for B. canis-if confirmed, euthanasia recommended due to lack of successful treatment and to prevent spread of infection; may try OHE and long-term antibiotics; discuss surveillance program for kennel situations: monthly serology for all individuals, culling any positive animals, until three consecutive negative tests are obtained; discuss zoonotic potential.
• Primary uterine disease-OHE is indicated in patients with no breeding value; cystic endometrial hyperplasia is an irreversible change.
• Infertility or pregnancy loss-may recur in subsequent estrous cycles despite successful immediate treatment.
• Prostaglandin treatment-discuss side effects (see Abortion, Termination of Pregnancy).
• Infectious diseases-establish surveillance and control measures.

Surgical Considerations

OHE-preferred for stable patients with no breeding value.

Drug(s) of Choice

• PGF₂ (Lutalyse, dinoprost tromethamine)-uterine evacuation after abortion; 0.05–0.1 mg/kg SC q8–24h; cloporostenol (Estrumate, cloprostenol)-1–5 µg/kg SC q24h; not approved for use in dogs, but adequate documentation legitimizes its use; use only if all living fetuses have been expelled.
• Antibiotics-for bacterial disease; initially institute broad-spectrum agent; specific agent depends on culture and sensitivity testing of vaginal tissue or necropsy of fetus.
• Progesterone (Regu-Mate) at 0.088 mg/kg (1 mL/25 kg PO q24h); progesterone in oil at 2 mg/kg IM q48–72h; progesterone (Prometrium^®; 10 mg/kg PO q24h, adjust daily dosage based on serum progesterone)-for documented hypoluteodism only to maintain pregnancy, must have accurate due date to know when to discontinue therapy-inadvertently prolonging gestation will result in fetal death.

Contraindications

Progestogen supplementation-contraindicated in dogs with endometrial or mammary gland disease.

Precautions

PGF₂-metabolized in the lung; side effects are related to smooth muscle contraction, are dose-related, and diminish with each injection; panting, salivation, vomiting, and defecation common; dosing critical (LD₅₀ for dinoprost-5 mg/kg).

Alternative Drug(s)

Oxytocin-1 U/5 kg SC q6–24h for uterine evacuation; should only be considered in cases where uterine evacuation is desired solely through uterine contraction.

Patient Monitoring

• Partial abortion-monitor viability of remaining fetuses with ultrasonography; monitor systemic health of the dam for remainder of pregnancy.
• Vulvar discharges-daily; for decreasing amount, odor, and inflammatory component; for consistency (increasing mucoid content is prognostically good).
• PGF₂-continued for 5 days or until most of the discharge ceases (range 3–15 days).
• B. canis-monitor after neutering and antibiotic therapy; yearly serologic testing to identify recrudescence.
• Hypothyroidism-treat appropriately; neutering recommended (hereditary nature); see Hypothyroidism.

Prevention/Avoidance

• Brucellosis and other infectious agents-surveillance programs to prevent introduction to kennel.
• OHE-for bitches with no breeding value.
• Use of modified-live vaccines (e.g., some distemper, parvovirus, etc., vaccines).

Possible Complications

• Untreated pyometra-septicemia, toxemia, death.
• Brucellosis-discospondylitis, endophthalmitis, recurrent uveitis.

Expected Course and Prognosis

• Pyometra-recurrence rate during subsequent cycle is high (up to 70%) unless pregnancy is established.
• CEH-recovery of fertility unlikely; pyometra common complication.
• Hormonal dysfunction-often manageable; familial aspects should be considered.
• Brucellosis-guarded; extremely difficult to successfully eliminate infection even if combined with neutering.

Age-Related Factors

Older bitches more likely to have CEH

Zoonotic Potential

B. canis-can be transmitted to humans, especially when handling the aborting bitch and expelled tissues; massive numbers of organisms expelled during abortion. Pathologists should be warned when B. canis is suspected. People that are immunocompromised are at greatest risk for infection.

See Also

• Brucellosis
• Hypothyroidism
• Infertility, Female-Dogs
• Premature Labor
• Pyometra

Abbreviations

• CEH = cystic endometrial hyperplasia
• OHE = ovariohysterectomy
• PGF₂ = prostaglandin F₂

Client Education Handout Available Online