A newborn mouse, often called a “pinky,” enters the world in a state of complete vulnerability. Born hairless with translucent pink skin, it is also blind and deaf, with its eyes and ears sealed shut. These tiny creatures are entirely dependent on their mother for every aspect of survival, from nutrition and warmth to basic hygiene. Without her constant care, a newborn pup has little chance of making it through its first few days.
Developmental Timeline of a Newborn Mouse
At birth, a mouse pup is altricial, meaning it is underdeveloped and requires significant parental care. It cannot regulate its own body temperature and relies on the warmth of its mother and littermates. Within the first few days, between days two and four, the first signs of development appear as skin pigment darkens and fine hair begins to emerge. This initial fuzz offers the first layer of insulation.
By the fifth to seventh day, the pups’ ears typically open between days three and five. A coat of fur starts to become more apparent around day six, and by day ten, it is fully grown. During this time, the pups also begin to develop mobility, starting with slight crawling motions within the nest as they seek out their mother for nourishment.
Between days 10 and 14, the pups’ eyes open. This sensory development marks a turning point, as they start to perceive their surroundings visually. Their movements become more coordinated, and they begin to explore the immediate vicinity of the nest. Though they are still nursing, this newfound mobility and awareness are the first steps toward independence.
The weaning process begins around day 21. By this stage, the young mice are fully furred, closely resembling miniature adults. They actively explore their environment, venturing further from the nest and beginning to nibble on solid foods provided by their mother. While nursing may continue for a short while longer, this transition to solid food marks the end of their complete dependency.
The Role of the Mother
The mother mouse provides the intensive care that is fundamental to her pups’ survival. Her primary role is to supply nutrition through nursing, which she does frequently. The milk is not only food but also a source of hydration and contains antibodies that help build the pups’ immune systems. She establishes a unique scent for her litter through her milk and urine, which helps in social identification.
Beyond feeding, the mother is the sole source of warmth for her offspring. She constructs a well-insulated nest and huddles over her pups, using her own body heat to maintain their temperature. The mother is vigilant, ensuring the nest remains a safe and stable environment.
Hygiene is also the mother’s duty. She regularly licks the pups to keep them clean and to stimulate their urination and defecation, as they are unable to perform these functions on their own initially. This cleaning also reinforces the bond between mother and pup. If a pup wanders or is moved from the nest, the mother has a strong retrieval instinct, carrying it back to safety.
What to Do if You Find Orphaned Pups
Discovering orphaned newborn mice presents a significant challenge, as hand-rearing them is exceptionally difficult and has a low success rate. The immediate priority is to provide a source of warmth, as they will quickly succumb to cold. A temporary nest can be made in a small, ventilated container lined with soft cloth, placed on a heating pad set to low and positioned so that it only covers half the container, allowing the pups to move away from the heat if necessary.
Feeding is the next urgent concern. Cow’s milk is not suitable and can be harmful to their digestive systems. A specialized formula, such as a kitten milk replacer or a goat’s milk-based puppy formula, should be used. The formula should be warmed and offered every two to three hours using a tiny, sterile instrument like a 1mL syringe or a small paintbrush, allowing the pup to lick the droplets.
After each feeding, it is necessary to stimulate the pups to urinate and defecate. This is done by gently stroking their genital and anal areas with a warm, damp cotton ball or cloth, a technique that mimics the mother’s licking. The best course of action is to contact a local wildlife rehabilitator or a veterinarian. These professionals have the proper resources and expertise to give the delicate pups their best chance.