METABOLIC SIMILARITY
The rat's metabolism is far more indicative of human disease than that of mice, making it a better model for studying ADME and cardiobiology.
COGNITIVE SIMILARITY
The cognitive behavior of rats is far more advanced than that of mice, making them suitable models for studying learning, memory, addiction and neurological diseases.
PHYSIOLOGICAL SIMILARITY
Rat physiology is better suited for the study of human toxicology, pharmacokinetics and immunology.
SIZE
Rats are simply larger animals, making surgical procedures and multiple blood extractions much more simple and successful.