How can you tell that a mouse is about to die? - briefly
Severe respiratory distress (rapid, shallow breaths, audible wheezing), profound lethargy or immobility, and pale or bluish extremities are primary signs of impending death in a mouse. When these symptoms appear together, humane euthanasia should be considered promptly.
How can you tell that a mouse is about to die? - in detail
Mice approaching the end of life display a consistent set of physiological and behavioral alterations that can be recognized without specialized equipment. Observers should focus on the following indicators:
- Decreased activity – prolonged periods of immobility, reduced exploration of the cage, and reluctance to climb or run.
- Loss of appetite and water intake – absence of food consumption for 24 hours, diminished drinking behavior, and visible empty food hoppers.
- Weight loss – measurable decline of more than 10 % of body mass over a few days, often accompanied by a sagging abdomen.
- Fur and skin condition – piloerection, dull coat, patches of alopecia, and the appearance of scabs or ulcerations.
- Respiratory changes – shallow, irregular breathing, audible wheezes, or increased respiratory rate that does not correspond to activity.
- Body temperature – peripheral chill and a drop of several degrees Celsius in core temperature, detectable by a rectal probe or infrared thermometer.
- Gait and posture – unsteady walking, dragging of limbs, or a hunched stance indicating musculoskeletal weakness or neurological decline.
- Ocular signs – clouded corneas, reduced blinking, or a sunken appearance of the eyes.
- Neurological signs – tremors, seizures, loss of righting reflex, or diminished response to tactile stimuli.
In research environments, these external signs are often corroborated by objective measurements:
- Telemetry data – continuous recording of heart rate and body temperature reveals progressive bradycardia and hypothermia.
- Blood chemistry – elevated blood urea nitrogen, creatinine, and liver enzymes indicate organ failure.
- Imaging – ultrasound or radiography may show tumor growth, organ enlargement, or fluid accumulation.
When multiple criteria converge, the probability of imminent mortality is high. Prompt humane intervention, such as euthanasia, should be considered to prevent unnecessary suffering.