Canine Reproductive Failure: A Diagnostic Approach Using PCR and Culture

Reproductive failure in dogs can be frustrating, costly, and diagnostically complex. Infertility, early embryonic loss, abortion, stillbirths, neonatal mortality, orchitis, epididymitis, and subfertility may all have infectious etiologies — yet identifying the underlying cause requires a structured and evidence-based approach.

Because no single test provides complete diagnostic certainty, combining PCR-based molecular diagnostics with aerobic bacterial culture and antimicrobial susceptibility testing offers the most comprehensive strategy.

This article outlines a practical diagnostic framework for evaluating infectious causes of canine reproductive failure in both females and males.

Why Infectious Causes Must Be Ruled Out Early

In breeding animals, infectious pathogens may:

• Reduce conception rates
• Cause embryonic resorption
• Trigger late-term abortion
• Lead to neonatal mortality
• Result in subclinical infertility
• Spread within breeding programs

Early and targeted diagnostic testing helps prevent repeated failed

breeding and supports kennel biosecurity.

Key Infectious Agents in Canine Reproductive Failure

1. Brucella canis Testing in Dogs

Brucella canis remains one of the most significant infectious causes of reproductive loss in dogs¹²³.

In females:

• Late-term abortion (typically 45–55 days gestation)
• Embryonic resorption
• Persistent vaginal discharge
• Infertility

In males:

• Epididymitis
• Orchitis
• Testicular atrophy
• Reduced semen quality

Dogs may appear clinically normal between reproductive events¹³.

Diagnostic Considerations

• Bacteremia can be intermittent
• Shedding varies over time
• Culture sensitivity may be limited
• Zoonotic risk requires strict handling precautions²

PCR enhances detection, particularly when combined with serologic screening³.

2. Canine Herpesvirus-1 (CHV-1)

CHV-1 contributes to:

• Early embryonic death
• Abortion
• Neonatal mortality (“fading puppy syndrome”)⁶

The virus establishes latency and may reactivate during stress or pregnancy⁶.

PCR is preferred for detecting active shedding in vaginal swabs, semen, placental tissue, or aborted fetuses⁶.

3. Mycoplasma spp. and Ureaplasma spp.

These organisms may be:

• Normal mucosal colonizers
• Opportunistic pathogens
• Associated with infertility, vaginitis, prostatitis, or reduced semen quality⁵

Because they are fastidious and difficult to culture, PCR improves detection sensitivity⁵. Interpretation must always be correlated with clinical findings.

4. Staphylococcus aureus and Streptococcus spp. (Female Panel)

In breeding females, opportunistic bacterial pathogens may cause:

• Vaginitis
• Endometritis
• Ascending uterine infections
• Pyometra
• Early embryonic loss
• Neonatal septicemia

Although these organisms can be part of normal flora, significant growth combined with inflammation supports pathogenic involvement².

Why Culture Is Essential

Culture confirms viable organisms and allows antimicrobial susceptibility testing — critical for targeted therapy and antimicrobial stewardship².

5. Leptospira spp. in Male Reproductive Diagnostics

Although leptospirosis is primarily associated with renal and hepatic disease, Leptospira spp. can localize in the reproductive tract and contribute to reproductive dysfunction⁷⁸.

Reported reproductive manifestations include:

• Orchitis
• Epididymitis
• Reduced semen quality
• Infertility
• Venereal transmission in some cases⁷

Leptospiral DNA has been detected in semen and reproductive tissues, and infected males may serve as asymptomatic carriers⁷⁸.

Diagnostic Considerations

• Shedding may be intermittent
• Serology indicates exposure but not necessarily active shedding
• PCR allows direct detection of organism DNA in reproductive samples⁷

Screening breeding males for Leptospira supports kennel biosecurity and reduces transmission risk.

Diagnostic Approach: Female Dogs

Recommended Testing

Whole Blood

Brucella canis PCR¹³

Vaginal Swab

CHV-1 PCR⁶

Mycoplasma spp. PCR⁵

Ureaplasma spp. PCR

Aerobic bacterial culture (including Staphylococcus aureus and Streptococcus spp.)²

Antimicrobial susceptibility testing

If Available

Placental or fetal tissues for PCR and culture⁶