Lavoisier’s respiration experiment in a guinea pig

Antoine-Laurent de Lavoisier (26 August 1743 – 8 May 1794) was a French noble prominent in the histories of chemistry and biology. He stated the first version of the law of conservation of mass, recognized and named oxygen and hydrogen

Lavoisier used a calorimeter to measure heat production as a result of respiration in a guinea pig. The outer shell of the calorimeter was packed with snow, which melted to maintain a constant temperature of 0 °C around an inner shell filled with ice. The guinea pig in the center of the chamber produced heat which melted the ice. The water that flowed out of the calorimeter was collected and weighed. Lavoisier found that 1 kg of melted ice corresponded to 80 kcal of heat production by the guinea pig. Lavoisier concluded: respiratory gas exchange is a combustion, like that of a candle burning.

In Western societies, the guinea pig has enjoyed widespread popularity as a household pet since its introduction by European traders in the 16th century. Their docile nature, their responsiveness to handling and feeding, and the relative ease of caring for them, continue to make the guinea pig a popular pet. Organizations devoted to competitive breeding of guinea pigs have been formed worldwide, and many specialized breeds of guinea pig, with varying coat colors and compositions, are cultivated by breeders.

Guinea pig is also used as a metaphor in English for a subject of experimentation; this usage became common in the first half of the 20th century. Biological experimentation on guinea pigs has been carried out since the 17th century; the animals were frequently used as a model organism in the 19th and 20th centuries, but have since been largely replaced by other rodents such as mice and rats. They are still used in research, primarily as models for human medical conditions such as juvenile diabetes, tuberculosis, scurvy, and pregnancy complications.

Lavoisier conducting an experiment on respiration in the 1770s.