Whelping and Queening in Dogs and Cats

Prediction Challenges:

• Conception vs. Breeding: Difficult to predict without ovulation timing due to the gap between estrual behavior and actual conception.

• Semen Viability: Sperm can remain viable in the reproductive tract for ≥7 days.

• Variable Factors: Breed, parity (number of previous pregnancies), and litter size can all influence length.

• Diagnostic Limitations:

    ◦ Radiography: Fetal skeletal mineralization timing varies at term.

    ◦ Fetal Size: Varies by breed and litter size.

Signs of Impending Labor

• Body Temperature Drop:

    ◦ Mean: 98.8°F (range 98.1°–100.0°F).

    ◦ Timing: Occurs 8–24 hours before whelping in most dogs.

    ◦ Labor Onset: Stage I labor typically begins within 24 hours of a decline to <99°F.

• Hormonal Changes: Serum progesterone drops to <2 ng/mL.

• Subtle Physical Changes (Non-specific):

    ◦ Relaxation of the perineum.

    ◦ Mammary engorgement.

    ◦ Changes in the appearance of the gravid abdomen.

Monitoring and Diagnostic Testing

• Progesterone Monitoring Issues:

    ◦ In-house kits: Often inaccurate between 2 and 5 ng/mL.

    ◦ Commercial labs: 12- to 24-hour turnaround is often too slow for immediate obstetric decisions.

    ◦ Speed of Change: Progesterone can drop rapidly in just a few hours.

• Best Practice: Determine the onset of cytologic diestrus (diestrual shift) to accurately evaluate gestation length at term.

Intervention Considerations

• Premature Intervention: Highly undesirable because there is no effective way to manage premature puppies.

• Elective Cesarean Section: Safely performed at >62 days gestation to ensure neonatal surfactant is reliably present.

• Induction: No safe, predictable way to induce parturition has been developed, though progesterone antagonists (aglepristone) show promise.

• Risk Balance: Clinicians must avoid being excessively conservative to prevent intrauterine fetal death.