Why do rats die? - briefly
Rats die from disease, predation, starvation, toxic exposure, and age‑related organ failure. In laboratory environments, euthanasia or experimental interventions also cause mortality.
Why do rats die? - in detail
Rats succumb to a wide range of lethal factors that can be grouped into disease, predation, environmental stress, toxic exposure, physical trauma, and senescence.
Diseases dominate mortality in dense populations. Bacterial infections such as Salmonella and Leptospira infiltrate the bloodstream, causing septicemia. Viral agents, notably hantavirus and rat coronavirus, damage respiratory and hepatic tissues. Parasitic infestations—Toxoplasma gondii, Trichinella spiralis, and various nematodes—lead to organ failure and malnutrition.
Predators impose direct mortality. Cats, birds of prey, snakes, and larger mammals capture and consume rats, especially juveniles lacking defensive experience. In urban settings, feral dogs and other rats engage in lethal aggression.
Environmental conditions create lethal stress. Extreme heat accelerates dehydration and heat‑stroke; severe cold induces hypothermia and frostbite. Floods, droughts, and habitat destruction remove shelter and food, forcing rats into suboptimal foraging zones where exposure risks increase.
Toxic agents contribute significantly. Rodenticides (anticoagulants, bromethalin) interfere with blood clotting or neuronal function, leading to internal bleeding or paralysis. Heavy metals (lead, mercury) accumulate in tissues, disrupting enzymatic pathways. Pesticides and industrial chemicals can cause organ toxicity after acute or chronic exposure.
Physical injury results from accidents and intra‑specific conflict. Falls from heights, crushing in machinery, or entrapment in traps produce fatal trauma. Aggressive encounters between individuals often end with severe wounds that become infected or cause blood loss.
Aging inevitably reduces physiological resilience. Cellular senescence, diminished immune response, and organ wear‑and‑tear lower the ability to cope with disease and stress, culminating in natural death after several years, depending on species and environmental pressures.
Collectively, these factors explain the high turnover observed in rat populations and illustrate the multifactorial nature of their mortality.