Toxicity tests on rats: gavage administration as cause of death
- Press release
Study reveals high number of deaths and injuries
A new scientific investigation shows that administering test substances to rats via gavage causes severe injuries and deaths far more often than previously assumed. The study, published in the journal Alternatives to Laboratory Animals and conducted by Dr. Katy Taylor and colleagues, analysed 300 toxicity tests carried out between 2004 and 2023 under the European chemicals regulation REACH.
In 21 percent of the examined studies, deaths or clinical abnormalities such as respiratory distress occurred that were directly attributable to the gavage procedure. Another 16 percent showed symptoms that may be linked to this method. For an individual animal, this corresponds to a risk of death of 1 in 250 during administration — and in longer studies (90 days), the risk was three times higher than in 28-day studies.
Gavage — the insertion of a metal tube into the stomach through the throat and oesophagus, performed daily without anaesthesia — can cause severe damage: perforated tracheas, injured organs, and fluid accumulation in the lungs were regularly documented. The procedure is also highly stressful: elevated body temperature, increased cortisol levels, weight loss, and liver damage were observed.
Beyond the animal welfare concerns, the authors also question the scientific validity of such tests. Complications caused by the gavage procedure can easily be mistaken for effects of the tested substance. This creates a risk that chemicals may be wrongly classified as toxic or irritating. Stress responses in the animals can further distort the results.
“The study shows that this method not only causes severe suffering but also compromises the reliability of toxicological studies,” says Dr. Corina Gericke, vice chair of Doctors Against Animal Experiments. “The already poor transferability of animal experiment results to humans is further undermined by the damage caused purely by the method of administration. Moreover, there is already a wide range of animal-free methods available for testing substances.”
References
Taylor K., Rego Alvarez L. & Grange E. The prevalence of reported gavage incidents in repeated dose toxicity studies involving rats conducted between 2004–2023. Alternatives to Laboratory Animals 2025; 53(3): 154-167