How old is the oldest rat? - briefly
The longest‑documented rat reached just over four years of age, with the record holder living approximately 4 years and 3 months. This exceeds typical lifespans of 2–3 years for most rats.
How old is the oldest rat? - in detail
The longest verified lifespan for a laboratory rat reached 4 years and 8 months (approximately 56 months). The record was set by a male Sprague‑Dawley rat named “Bart” at the University of California, Davis, which died in August 2018 after a controlled diet and regular health monitoring.
Key factors contributing to such longevity include:
- Genetic strain – Sprague‑Dawley and other outbred strains tend to live longer than wild‑caught or feral rats.
- Environmental control – Stable temperature (20‑22 °C), low humidity, and minimal stress reduce mortality.
- Dietary regimen – Balanced rodent chow with restricted caloric intake prolongs life without compromising health.
- Veterinary oversight – Routine examinations detect disease early, allowing timely intervention.
In contrast, typical pet rats of the same strain average 2‑3 years, while wild brown rats (Rattus norvegicus) rarely exceed 1 year due to predation, disease, and harsh conditions. Longevity studies often use the maximum recorded age as a benchmark for evaluating aging interventions, pharmacological treatments, and genetic modifications.