Intraperitoneal Injection of Neonatal Mice

Administration of substances into neonatal mice is required for early treatment with pre-clinical therapeutics, delivery of recombination-inducing substances, and dosing with viruses or toxins, amongst other things. Several injection routes into mouse pups are possible, including intravenous and intracerebroventricular, each with their own advantages and limitations. Here, we describe a simple and rapid protocol for the intraperitoneal injection of neonatal mice for systemic dosing. By detaching a 30-gauge needle from its plastic hub and inserting it into polyethylene tubing attached to a Hamilton syringe, small volumes (1–10 μL) can be accurately injected into the peritoneal cavity of pups aged 1–5 days old. The procedure can be completed within a few minutes, is generally safe and well tolerated by both pups and parents, and can be used in combination with alternative administration routes. Key features • This protocol provides a simple description to rapidly and efficiently inject mouse pups aged 1–5 days for systemic dosing. • Allows treatment of neonatal mice with substances such as viruses and compounds for research across disciplines.