How can I give medicine to a rat by mouth? - briefly
Use a calibrated oral gavage needle or a precision pipette to deliver the measured dose directly into the rat’s mouth, positioning the tip at the back of the oral cavity while gently restraining the animal. Verify that the volume matches the rat’s weight and watch for proper swallowing.
How can I give medicine to a rat by mouth? - in detail
Administering oral medication to a laboratory rat requires careful preparation, proper restraint, and precise dosing. Follow these steps to ensure reliable delivery and minimize stress on the animal.
First, verify the drug’s concentration, required dose (mg kg⁻¹), and vehicle compatibility. Calculate the exact volume for the individual rat using its current weight. Prepare the dose in a calibrated syringe or a calibrated oral gavage needle (20‑22 G, 1–2 ml capacity). If the compound is viscous or poorly soluble, dilute with an appropriate carrier (e.g., sterile water, saline, or a buffered solution) and mix thoroughly to achieve a uniform suspension.
Second, select an appropriate restraint method. The most common technique involves placing the rat on a soft, non‑slipping surface, securing the forepaws with gentle pressure using a gloved hand, and holding the head with the thumb and forefinger to expose the oral cavity. Alternatively, a transparent restraining tube can be used, provided the animal is acclimated to the device.
Third, insert the gavage needle. Tilt the rat’s head slightly upward, open the mouth by gently pulling the lower jaw forward, and advance the needle along the palate, avoiding the teeth. The needle tip should rest just above the esophageal opening; insertion depth is typically 2–3 cm for adult rats. Confirm placement by observing a brief pause in respiration and a smooth flow of the liquid without resistance.
Fourth, deliver the medication. Depress the syringe plunger slowly to release the calculated volume. After administration, withdraw the needle carefully, hold the rat upright for 10–20 seconds to allow the solution to travel down the esophagus, and observe for signs of regurgitation or aspiration. Return the animal to its cage and monitor for any adverse reactions for at least 30 minutes.
Additional considerations:
- Use sterile, single‑use equipment for each animal to prevent cross‑contamination.
- Record the exact dose, time of administration, and any observations in the animal’s log.
- For bitter or irritating compounds, consider flavor masking agents or a brief pre‑treatment with a palatable carrier to improve acceptance.
- If the rat resists oral gavage, practice habituation sessions over several days to reduce stress.
- In case of accidental aspiration, position the animal upright, monitor respiratory rate, and be prepared to provide supportive care or veterinary intervention.
By adhering to these procedures, oral drug delivery in rats can be performed safely, reproducibly, and with minimal impact on animal welfare.