How to determine if a rat has a fever? - briefly
Insert a lubricated rectal thermometer to read the core temperature; a reading above 101 °F (38.3 °C) indicates fever in a rat. Confirm with signs such as lethargy, shivering, or loss of appetite.
How to determine if a rat has a fever? - in detail
Rats maintain a core temperature between 37 °C and 38 °C (98.6 °F–100.4 °F). Values above this interval suggest a febrile state and warrant further evaluation.
Direct temperature measurement
- Use a digital rectal thermometer designed for small mammals. Lubricate the probe, insert it 1 cm into the anal canal, and hold steady until the reading stabilizes (typically 5–10 seconds). Record the temperature to the nearest 0.1 °C.
- Infrared thermometers can assess ear or surface temperature, but they require calibration against rectal readings because peripheral measurements underestimate core values by 1–2 °C.
- Implantable telemetry devices provide continuous core data without handling stress; surgical implantation must follow aseptic technique and allow recovery before data collection.
Clinical signs accompanying elevated temperature
- Reduced activity, lethargy, or unwillingness to explore.
- Decreased food and water intake.
- Flushed or reddened ears and tail.
- Rapid, shallow breathing (tachypnea).
- Piloerection and huddling behavior.
Interpreting results
- Rectal temperature ≥ 39 °C (102.2 °F) constitutes a definitive fever.
- Readings between 38.5 °C and 38.9 °C (101.3 °F–101.9 °F) are borderline; corroborate with clinical signs and repeat measurement after 30 minutes.
- Temperatures below 36.5 °C (97.7 °F) may indicate hypothermia, especially in cold environments or after anesthesia.
Additional considerations
- Ambient temperature influences peripheral measurements; maintain the housing environment at 20 °C–22 °C (68 °F–72 °F) during assessments.
- Minimize handling time to reduce stress‑induced hyperthermia.
- Verify thermometer accuracy daily with a calibrated reference point.
- Record the time of day, recent feeding, and any medications, as these factors can affect thermoregulation.
Accurate detection of fever in rats relies on precise core temperature measurement, recognition of accompanying behavioral changes, and consistent documentation of environmental and procedural variables.