Oral gavage (also called gastric gavage or intragastric dosing) is a technique for administering a precise, measured volume of liquid substance directly into the stomach of a laboratory animal. A ball-tipped feeding needle — a stainless steel needle with a smooth, rounded ball at the tip — or a flexible polyurethane or silicone catheter is passed through the animal's mouth, over the tongue, and gently guided down the oesophagus into the stomach. The substance is then delivered by depressing the syringe plunger. Oral gavage is the method of choice in preclinical research when accurate, reproducible oral dosing is required.
Oral gavage is used across a wide range of study types: pharmacokinetic and bioavailability studies (measuring how a compound is absorbed, distributed, metabolised, and excreted), acute and chronic toxicology studies, nutritional and dietary intervention experiments, and efficacy testing of orally administered compounds. It is preferred over voluntary feeding or drinking when the dose must be precisely controlled, when the compound has unpalatable properties, or when the timing of administration relative to the study protocol must be exact.
The most critical aspect of needle selection is matching gauge and length to the animal. Gauge determines the outer diameter of the needle — a lower gauge number indicates a larger diameter. For adult mice (20–35 g), 20- to 22-gauge needles are commonly used. For adult rats (200–400 g), 16- to 18-gauge needles are appropriate. Length is selected based on the distance from the animal's mouth to its stomach — typically measured externally as the distance from the tip of the nose to the last rib. Using a needle that is too long risks penetrating the stomach wall or entering the intestine; too short, and the needle tip remains in the oesophagus, risking oesophageal delivery or reflux.
The ball tip is the defining safety feature of a gavage needle. The rounded, polished ball prevents the needle from perforating the delicate oesophageal mucosa during insertion. Needles without a ball tip (such as sharp hypodermic needles) must never be used for oral gavage, as they carry a high risk of oesophageal laceration. Ball-tipped needles are available in stainless steel for reusable applications and in disposable configurations. Some practitioners use flexible polyurethane or silicone catheters instead of metal needles — these reduce the risk of oesophageal injury from animal movement during dosing, at the cost of slightly less tactile feedback during placement.
Common errors in oral gavage technique include oesophageal delivery rather than gastric delivery (compound deposited in the oesophagus rather than the stomach, causing oesophageal irritation or necrosis if the compound is acidic or caustic), accidental tracheal intubation (the needle enters the airway rather than the oesophagus, leading to pulmonary aspiration of the dosed substance — often fatal), and administration of excessive volume (gastric volumes exceeding recommended limits cause distension and stress). For mice, typical maximum gavage volumes are 10 mL/kg body weight; for rats, 10 mL/kg is also a common guideline, though up to 20 mL/kg may be used in some protocols. Always refer to institutional animal ethics guidelines for approved volumes.
Key Points
- Ball-tipped feeding needle or flexible catheter delivers precise volumes directly to the stomach
- Used in pharmacokinetics, toxicology, nutritional studies, and oral drug efficacy testing
- Needle gauge and length must be matched to species and body weight
- Ball tip prevents oesophageal perforation — never use sharp needles for gavage
- Common errors: oesophageal delivery, accidental tracheal intubation, excessive volume
Relevant Standards
- OECD Test Guidelines (specify gavage as the dosing method for acute oral toxicity studies)
- ARRIVE Guidelines (reporting standards for animal research — require documentation of dosing route and volume)
- Institutional animal ethics committee (AEC in Australia; IACUC in North America) protocols govern approved gavage volumes and technique
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Frequently Asked Questions
What is the difference between a gavage needle and a regular syringe needle?
A gavage needle has a smooth, rounded ball at its tip rather than a sharp cutting bevel. The ball tip prevents the needle from perforating the oesophagus during insertion and provides a blunt leading edge that slides through the mouth and oropharynx without lacerating tissue. Regular hypodermic needles must never be used for oral gavage — their sharp tips will perforate the oesophagus.
How do I choose the right gavage needle size for my animals?
Select gauge based on animal size: 20–22 gauge for mice, 16–18 gauge for rats (smaller gauges for younger or lighter animals within each species). Select length by measuring the external distance from the tip of the nose to the last rib on a representative animal — the needle tip should reach the stomach but not extend beyond it. Instech feeding tubes are available in a range of gauge and length combinations to match common rodent models.
How do I know if I have accidentally intubated the trachea?
If the needle has entered the trachea, you will typically feel very little resistance during insertion (the trachea is wider and more open than the oesophagus), and the animal may show respiratory distress or struggle during or immediately after dosing. If the compound enters the lungs (pulmonary aspiration), death from respiratory failure may occur rapidly. If tracheal placement is suspected, withdraw the needle immediately without depressing the plunger. Confirm correct oesophageal placement by palpating the neck or observing the swallowing reflex as the needle is advanced.
What is the maximum volume I can administer by gavage?
For most rodent studies, a maximum of 10 mL/kg body weight is the standard guideline for single gavage administrations in mice and rats, though some protocols allow up to 20 mL/kg in rats for specific applications. Volumes above these limits cause gastric distension, stress, and can affect compound absorption kinetics. Always work within volumes approved by your institutional animal ethics committee, and adjust concentration of the dose formulation to achieve the target dose within the approved volume.