What are the most common causes of death in rats? - briefly
Age‑related organ failure, neoplastic disease, and severe infections (bacterial, viral, or parasitic) account for the majority of rat mortality. In research colonies, trauma, anesthesia complications, and environmental stressors also contribute significantly.
What are the most common causes of death in rats? - in detail
Rats most frequently die from disease, organ failure, toxic exposure, and trauma.
Bacterial infections dominate morbidity. Sepsis caused by Salmonella or Streptococcus species can overwhelm the immune system, leading to rapid cardiovascular collapse. Pasteurella multocida produces pneumonia that progresses to respiratory failure, especially in crowded colonies.
Viral agents contribute significantly. Rat coronavirus (RCV) induces enteric and respiratory lesions, while Sendai virus produces severe bronchopneumonia. Both agents spread easily in dense populations and often result in death within days of onset.
Parasitic infestations, particularly cestodes (Hymenolepis spp.) and nematodes (Syphacia muris), cause chronic malnutrition, intestinal obstruction, and secondary bacterial translocation, which can be fatal in weakened hosts.
Neoplastic disease is a common late‑stage cause. Mammary adenocarcinomas, lymphomas, and adrenal pheochromocytomas frequently metastasize, impairing organ function and precipitating cachexia. Tumor‑associated hemorrhage or organ compression often leads to sudden death.
Renal and hepatic insufficiency arise from chronic exposure to toxins, diet‑induced metabolic stress, or age‑related degeneration. Acute kidney injury from urethral blockage or hemolytic uremic syndrome progresses to uremia and cardiovascular collapse. Hepatocellular necrosis, whether toxin‑induced (e.g., carbon tetrachloride) or viral, compromises coagulation and leads to fatal hemorrhage.
Cardiovascular disorders include myocardial infarction, cardiomyopathy, and arrhythmias. Hypertensive stress, atherosclerotic changes, or genetic predisposition cause ventricular dysfunction and sudden cardiac arrest.
Respiratory failure can result from pulmonary edema, aspiration pneumonia, or chronic obstructive disease. Environmental factors such as poor ventilation or high ammonia levels exacerbate alveolar damage, leading to hypoxia.
Gastrointestinal emergencies—intussusception, volvulus, or obstruction by foreign material—produce acute abdominal distention, ischemia, and peritonitis, often ending in rapid mortality if untreated.
Chemical poisoning remains a prevalent cause in both laboratory and pet settings. Anticoagulant rodenticides (warfarin, brodifacoum) cause uncontrolled hemorrhage; heavy metals (lead, zinc) induce neurotoxicity and organ failure; pesticides trigger cholinergic crisis and respiratory paralysis.
Physical trauma includes cage injuries, bite wounds from conspecific aggression, and accidental crushing. Severe hemorrhage, spinal cord damage, or traumatic brain injury frequently result in immediate death.
Senescence, while not a discrete pathology, leads to cumulative organ decline. Age‑related immunosenescence predisposes older rats to opportunistic infections, while progressive loss of cardiac and renal reserve reduces resilience to stressors.
In summary, mortality in rats is multifactorial: infectious agents (bacterial, viral, parasitic), neoplasia, organ failure (renal, hepatic, cardiac), respiratory compromise, gastrointestinal catastrophes, toxicants, trauma, and age‑related degeneration each play a substantial role. Effective prevention requires stringent hygiene, environmental control, regular health monitoring, and prompt intervention when clinical signs emerge.