What are the signs of rat pregnancy? - briefly
A pregnant female rat shows a noticeably enlarged abdomen, pink and enlarged nipples, and a marked increase in nesting activity. Additional indicators include steady weight gain and reduced aggression.
What are the signs of rat pregnancy? - in detail
Pregnant rats display several physiological and behavioral changes that become apparent as gestation progresses. Early in the cycle (first 7‑10 days) the abdomen may appear slightly enlarged, but the most reliable indicators emerge after the second week.
- Abdominal swelling: The belly expands noticeably as embryos develop; the increase is uniform and not accompanied by sharp edges that characterize tumors.
- Milk line development: Small pinkish patches appear along the ventral midline, later forming functional mammary glands.
- Nesting behavior: Females gather bedding, shred material, and construct a nest, often beginning around day 14.
- Weight gain: A steady rise of 5‑10 g per week is typical; rapid, irregular fluctuations suggest health issues rather than pregnancy.
- Hormonal changes: Elevated prolactin and progesterone levels cause a duller coat and reduced grooming; the fur may look slightly fluffed.
- Reduced fertility signs: Estrous cycles cease; the female no longer exhibits the regular swelling and discharge associated with heat.
- Increased appetite: Food consumption rises to meet the metabolic demands of the developing litter.
- Maternal aggression: The rat may become more defensive of her enclosure, especially when approached near term.
By day 18‑21, the uterus is fully distended, and the mammary glands become prominent and may secrete a faint milk. Observation of these combined traits provides a clear diagnosis of gestation without the need for invasive procedures.