Oral gavage of a substance in the rat
Key points to note
The material can be administered orally using a number of different techniques, although gavage using a stomach tube is the most widely used. To minimise the risk of adverse effects associated with this procedure, it is important that the operator is skilled both in the technique and the restraint method needed.
Although gavage can be undertaken using rigid dosing cannulae, flexible catheters or tubes are preferred, as these are less likely to cause oesophageal trauma. Inadvertent dosing into the lung can occur, which usually results in the animal showing immediate signs of respiratory distress. If such signs are observed, then the animal should be immediately humanely killed.
As an alternative to gavage, some materials may be consumed voluntarily in palatable mixtures (e.g. flavoured syrups, Leach et al, 20101, Corbett et al, 20122). Rats can also be trained to drink voluntarily from a syringe (see video below) and this approach has been shown to be both effective and to result in accurate dosing (Atcha et al, 20103).
Material can also be dosed using a small flexible catheter introduced only into the animal’s mouth. When possible, these approaches are to be preferred to dosing using a stomach tube, since they are not associated with complications, such as tracheal dosing or oesophageal rupture.
A rat trained to drink voluntarily from a syringe