How long do laboratory rats live? - briefly
Laboratory rats usually live between two and three years when kept under standard research conditions; in optimal environments some individuals may reach four years.
How long do laboratory rats live? - in detail
Laboratory rats (Rattus norvegicus) typically survive 2 to 3 years under standard research conditions. Median survival is about 24 months; many individuals reach 30 months, and a few exceed 36 months when environmental stressors are minimized.
Key variables influencing longevity:
- Strain – Inbred lines (e.g., Fischer 344, Sprague‑Dawley) often have shorter lifespans than outbred stocks because of reduced genetic diversity.
- Sex – Females usually live 10–15 % longer than males, reflecting hormonal and metabolic differences.
- Housing – Group housing with enrichment (nesting material, tunnels) extends life expectancy relative to isolated, barren cages.
- Diet – Ad libitum access to standard rodent chow maintains stable weight; caloric restriction can increase maximum lifespan by up to 20 %.
- Health monitoring – Routine pathogen screening and veterinary oversight prevent infectious outbreaks that dramatically shorten survival.
- Genetic manipulation – Transgenic or knockout models may exhibit premature aging or disease phenotypes that reduce lifespan, sometimes to less than 12 months.
Typical mortality causes in a research setting include neoplasms (particularly in older animals), cardiovascular disease, renal failure, and age‑related decline in immune function. When euthanasia is performed for experimental endpoints, recorded lifespan may be shorter than natural expectancy.
Reported maximum ages for laboratory rats range from 4 to 5 years, achieved only under exceptionally low‑stress, pathogen‑free environments with rigorous husbandry. These outliers illustrate the upper biological limit but are not representative of routine colony performance.