Oral Gavage Versus Feed Mixture Exposure Methods in Environmental Toxicology Studies: Advantages and Limitations

Oral exposure is a widely used route in animal toxicology and pharmacology studies. Two common methods, gavage and mixing substances with drinking water or feed, have distinct implications on dosing accuracy, animal welfare, and physiological outcomes. This scoping review aims to compare the advantages and disadvantages of gavage and feed mixture methods for oral administration in animal models, evaluating their impacts on dosing precision, stress response, and experimental variability. Relevant studies comparing gavage and mixing exposure routes in mice and rats were identified through a comprehensive search of major scientific databases according to PRISMA guidelines. Data on physiological, behavioral, and methodological outcomes were extracted and analyzed. Gavage was found to provide precise and controlled dosing but was associated with increased stress and may result in damage to the esophagus and stomach, which may contribute to the attrition of laboratory rodents. Conversely, blending with food or water lowers stress and aggressiveness; on the other hand, this method is similar to the animal's contact with pollutants in the environment. Both approaches revealed particular strengths and shortcomings that have an impact on the design and interpretation of the research. Selecting the appropriate oral exposure method depends on the study's objectives, required dosing accuracy, and duration.