How do dumbo rats give birth? - briefly
«Dumbo rats» complete gestation in about three weeks, then the dam initiates uterine contractions that expel each pup through the vaginal canal, followed by individual placental membranes. The process mirrors that of standard laboratory rats, requiring no special intervention.
How do dumbo rats give birth? - in detail
Dumbo rats, a laboratory strain distinguished by enlarged auricles, follow the same mammalian reproductive sequence as other Rattus norvegicus specimens, with specific adaptations linked to their phenotype.
Gestation lasts approximately 21‑23 days. During this interval, the corpora lutea secrete progesterone, maintaining uterine quiescence. Around day 15, the placenta produces increasing levels of estrogen, triggering uterine muscle remodeling and preparing the cervix for dilation.
Parturition proceeds through three stages:
• First stage – cervical dilation and uterine contractions intensify, observable as rhythmic abdominal movements.
• Second stage – expulsion of pups occurs in rapid succession, each delivered head‑first or occasionally breech. The average litter comprises 8‑12 neonates, though numbers may vary with maternal age and health.
• Third stage – delivery of the placenta (afterbirth) follows each pup, accompanied by a brief increase in oxytocin release that promotes uterine involution.
Immediately after birth, the dam initiates nest‑building behavior, arranging shredded paper or bedding to provide thermal insulation. She cleans each offspring with her incisors, stimulating respiratory effort and circulation. Pups are altricial: eyes remain closed, fur is sparse, and thermoregulation is dependent on maternal warmth. The dam nurses within the first hour, delivering colostrum rich in immunoglobulins essential for passive immunity.
Hormonal feedback loops regulate the entire process. Prolactin levels rise during lactation, sustaining milk production, while elevated prolactin and oxytocin together suppress the estrous cycle, preventing immediate re‑entry into fertility until weaning is complete.
Successful reproduction in this strain requires:
1. Adequate nutrition for the dam, ensuring sufficient protein and calcium for milk synthesis.
2. Stable ambient temperature (22‑24 °C) to prevent hypothermia in neonates.
3. Minimal stressors, as corticosterone spikes can delay parturition and reduce litter viability.
These physiological and behavioral components constitute the detailed birthing mechanism of dumbo rats.