Endpoint methods library
Thermal nociception endpoint

Hot plate latency

Time from placement on a heated plate to a predefined nocifensive response such as hindpaw licking, withdrawal, shaking, or jumping.

Unit
seconds
Readout
Latency from plate placement to the first predefined nocifensive response
Assays
Hot plate analgesia, thermal hyperalgesia, dose-response analgesic screening, tolerance studies

Decision summary

Use hot plate latency when the experiment needs a thermal nociception readout with a supraspinal response component. The endpoint is useful for analgesic screening and heat hyperalgesia work, but it should not be interpreted as pain intensity by itself. Interpretation is strongest when plate temperature, response criterion, cutoff, baseline latency, locomotor state, and sedation controls are fixed before testing.

Primary valueLatency from plate placement to the first predefined nocifensive response
Common unitsSeconds, usually capped at a protocol-defined cutoff
Compatible assaysHot plate analgesia, thermal hyperalgesia, dose-response analgesic screening, tolerance studies
Required boundaryPlate temperature, response definition, timer start, timer stop, and cutoff rule
Do not infer alonePain affect, drug efficacy, peripheral sensitivity, sedation, or motor competence

Measurement notes

Predefine the response list and apply the same rule to every animal. Common scoring endpoints include hindpaw lick, hindpaw withdrawal or shake, and jump. Record the plate temperature, cutoff, timer start rule, and whether ambiguous grooming or rearing behaviors are excluded.

Interpretation limit

Longer latency can support antinociception, but it can also reflect sedation, impaired motor output, altered attention, hypothermia, handling stress, or a response criterion that is too broad. Shorter latency may reflect hyperalgesia, anxiety-like escape, poor acclimation, or temperature drift.

Data capture

Store animal ID, group, trial number, plate temperature, cutoff, raw latency, cutoff-clamped latency, response type, baseline latency, time since dose, exclusion flag, observer, and apparatus verification notes.

Confound checks
  • Plate temperature drift or uneven heat distribution across the surface.
  • Different response definitions across observers or sessions.
  • Sedation, ataxia, weakness, hypothermia, or altered locomotor activity.
  • Repeated exposure without enough recovery time between trials.
  • Strain, sex, body weight, circadian timing, and acclimation differences.
Reporting checklist
  • Plate temperature, verification method, response criterion, and cutoff duration.
  • Trial count, inter-trial interval, baseline collection, and dose-to-test interval.
  • Whether latencies were raw, cutoff-clamped, averaged, or converted to percent maximum possible effect.
  • Observer blinding, video review rules, and treatment of ambiguous behaviors.
  • Companion controls for locomotion, sedation, body temperature, or motor impairment.
  • Species, strain, sex, age, body weight, housing, and acclimation conditions.