Definition

• Spontaneous abortion-natural expulsion of fetus(es) prior to the point at which they can sustain life outside the uterus.
• Early pregnancy loss-generalized term for any loss of conceptus including early embryonic death and resorption.

Pathophysiology

• Infectious causes result in pregnancy loss directly by affecting the embryo, fetus, or fetal membranes, or indirectly by creating debilitating systemic disease in the queen.
• Non-infectious causes of pregnancy loss result from any factor other than infection that leads to the death or premature expulsion of the conceptus (e.g., uterine disease, inadequate maternal nutrition, endocrine dysfunction, toxicity, genetic defects).

Systems Affected

• Endocrine
• Reproductive
• Other systems-any debilitating illness can result in pregnancy loss.

Genetics

Genetic defects are more prevalent in highly inbred individuals; heritability of susceptibility to FIPV thought to be very high.

Incidence/Prevalence

Unknown-pregnancy frequently not confirmed, owners may not recognize late pregnancy loss if the queen is fastidious; early embryonic death is difficult to document.

Signalment

Signs

Causes

Risk Factors

• Previous history of pregnancy loss
• Concurrent systemic disease
• Recent trauma
• Purebred cat with high degree of inbreeding
• Very young or old queen
• Previous use of progestins to suppress estrus
• Malnourishment
• Homemade and raw diets
• Overcrowded or unsanitary environment

Differential Diagnosis

• Early pregnancy loss-failure to conceive, disorder of sexual development, anovulatory cycle
• Vulvar discharge-pyometra, mucometra, uterine stump pyometra; vaginitis, metritis, cystitis; impending parturition or dystocia; neoplasia or trauma of urinary bladder, urethra, vagina, or uterus; estrus-very little discharge typically seen
• Abdominal straining or discomfort: urethral obstruction; intestinal foreign body; peritonitis; trauma; impending parturition or dystocia

CBC/Biochemistry/Urinalysis

• May be normal.
• Inflammatory leukogram or stress leukogram depending on systemic disease response.
• Hemoconcentration and azotemia with dehydration.

Other Laboratory Tests

Imaging

• Abdominal ultrasound in early gestation (21–25 days post-breeding) to confirm pregnancy and screen for evidence of resorption. Later pregnancy, evaluate health and viability of fetus(es) and associated fluid and membranes; abnormal uterine fluid accumulation and non-reproductive disease.
• Radiograph-evaluates relative size, number, and position of fetal skeletons; can also be used to screen for fetal monsters, fetal malpresentation, and non-reproductive disease.

Diagnostic Procedures

• Genetic defects-necropsy aborted fetus(es); submit samples from aborted and stillborn fetus for karyotyping.
• Nutrition-submit sample of diet for nutritional analysis: of particular importance when queen is fed a homemade and/or raw diet.
• Pedigree analysis to evaluate inbreeding coefficient
• Evaluate cattery for vaccination protocols, feeding regime, general sanitation procedures, and quarantine procedures for pregnant queens and new arrivals.
• Submit reproductive tract (uterus, ovaries, uterine tubes) and aborted, stillborn, mummified fetus(es) and fetal membranes (fresh, refrigerated, on wet ice) for evaluation of anatomic and pathologic changes, gross necropsy, histopathology, cultures, and viral isolation.

Appropriate Health Care

• Outpatient management: typically no medical management required for non-infectious stable queens; primary hypoluteoidism-can be managed on an outpatient basis with tocolytic drugs in combination with tocodynamometry.
• Surgical management: OHE for queens with severe illness due to pyometra or metritis.

Activity

• Isolation for queens with infectious disease.
• No activity restrictions for most non-infectious pregnancy losses.
• Restrict activity as indicated for pregnancy loss due to trauma.

Diet

Feed commercially available diet labeled for use in pregnancy. Correct diets with inappropriate taurine or vitamin A concentrations. Avoid feeding raw meats or allowing queens to hunt during pregnancy to reduce risk for ingestion of pathogenic bacteria and T. gondii.

Client Education

• Infectious diseases-verify client is following good vaccination protocols and disease surveillance measures and is utilizing quarantine facilities for pregnant queens and new arrivals.
• Breeding management-discuss normal reproductive behavior and good breeding management; advise clients to keep detailed records related to reproductive performance, pedigree analysis, and social behavior of queens within the cattery.
• Nutrition-discuss routine diet recommendations for breeding queens; advise homemade diets undergo nutritional analysis.
• Genetic disease-increase in inbred individuals; many reproductive traits are heritable.
• Discuss risk of zoonotic disease from Toxoplasma gondii.

Drug(s) Of Choice

• Will depend on etiology.
• Amoxicillin-clavulanic acid 13.75 mg/kg PO q12h or enrofloxacin 5 mg/kg/day PO based on bacterial culture results.
• Tocolytic therapy to prevent uterine contractions and help maintain pregnancy: Terbutaline 0.03–1.0 mg PO as needed based on tocodynamometry; 0.03 mg/kg PO q8h if tocodynometry not available.
• Hypoluteoidism: progesterone in oil-2.0–3.0 mg/kg IM as needed based on serum progesterone concentration and tocodynamometry.

Contraindications

• Terbutaline-cardiac or respiratory disease, pyometra, infectious disease, hypertension.
• Progesterone in oil-diabetes, pyometra, infectious disease, CEH.

Precautions

• Use of tocolytics to maintain pregnancy requires accurate documentation of breeding dates to know when treatment should be discontinued; tocolytics used most successfully in combination with tocodynamometry to establish desired dosing interval based on increasing preterm uterine activity.
• Terbutaline can cause hypertension leading to increased hemorrhage from the placental sites during parturition or at the time of c-section.

Possible Interactions

• Progesterone administration during pregnancy is associated with masculinization of female fetuses; do not administer in the first half of pregnancy and use with informed consent thereafter.
• Use of tocolytics to maintain pregnancy is associated with increased risk of dystocia, failure of normal placental separation at parturition, lack of mammary gland development and milk production, and poor maternal behavior for the first few days postpartum.

Patient Monitoring

• Serial ultrasound evaluation q 5–7 days to evaluate fetal viability for queens receiving tocolytics.

Prevention/Avoidance

• Institute infectious disease prevention, control, and surveillance plan.
• Replace infertile queens with more reproductively fit individuals.
• Avoid exposure to abortifacient, teratogenic, or fetotoxic drugs.

Possible Complications

• Depends on etiology.
• Metritis, endometritis, uterine rupture, sepsis, shock.
• Diabetes, CEH, masculinization of female fetuses with progesterone treatment.

Expected Course and Prognosis

• Infectious disease-normal pregnancy, repeated abortion, or infertility possible with viral disease.
• Poor prognosis for normal pregnancy in queens with severe CEH.
• Fair prognosis for successful pregnancy with treatment for primary hypoluteoidism; significant monitoring required for good outcome.
• Pregnancy loss due to genetic abnormalities likely to recur if queen is bred to tom with similar pedigree.

Age-Related Factors

• Queens >6 years old have higher incidence of infertility.
• Pregnancy loss seen most frequently in very young and old queens.

Zoonotic Potential

See Also

• Breeding, Timing
• Sexual Development Disorders

Abbreviations

• CEH = cystic endometrial hyperplasia
• ELISA = enzyme-linked immunosorbent assay
• FeLV = feline leukemia virus
• FHV-1 = feline herpesvirus 1
• FIPV = feline infectious peritonitis virus
• FIV = feline immunodeficiency virus
• FPLV = feline panleukopenia virus
• IFA = indirect fluorescent antibody
• OHE = ovariohysterectomy
• PGF₂ = prostaglandin F₂

Internet Resources

• www.theriojournal.com
• www.whelpwise.com

Client Education Handout Available Online