Administration by Oral Gavage

Liquid compounds may be administered directly into the stomach of mice and rats via a technique called oral gavage. In this procedure a bulb tipped gastric gavage needle is attached to a syringe and used to deliver the compound into the stomach. The bulb tip helps prevent trauma to the mouth and esophagus as the needle is introduced. Needles come in mouse and rat sizes and lengths. The correct needle length is equal to the distance from the mouth to just beyond the last rib.

The animal should be firmly restrained (grasp the animal by the loose skin of the neck and back) to immobilize the head. Maintain the animal in an upright (vertical) position and pass the gavage needle through the side of the mouth. Following the roof of the mouth, advance the needle into the esophagus and toward the stomach. If resistence is encountered you may be attempting to enter the trachea and you should alter your needle position. After the needle is passed to the correct length, the compound may be injected. If the animal coughs, chokes or begins to struggle vigourously after compound administration begins you may be injecting material into the lungs. If this occurs stop and withdraw the needle immediately. If it appears that material has been injected into the lungs the animal should be euthanized. Struggling during administration or excessive force in advancing the needle may lead to rupture of the esophagus or pharynx. If you suspect this has occurred the animal should be euthanized.

Volumes up to 10 ml/kg in the mouse and 20 ml/kg in the rat may be administered via oral gavage.