The presence of pain in animals is unknown, but can be inferred through physical and behavioral reactions, such as paw withdrawal from various noxious mechanical stimuli in rodents. See also
Feeling, a perceptual state of conscious experience. Hedonic adaptation, the tendency to quickly return to a relatively stable level of happiness despite major positive or negative events
Pain (philosophy), the branch of philosophy concerned with suffering and physical pain
Pain and suffering, the legal term for the physical and emotional stress caused from an injury

Explanatory notes
References
Casey K (2019). Chasing Pain: The Search for a Neurobiological Mechanism. New York: Oxford University Press. ISBN 978-0-19-088023-1. External links

Pain at Curlie
"Pain", Stanford Encyclopedia of Philosophy
This intensity will be less than the actual peak intensity if the duration of the rainfall event was less than the fixed time interval for which measurements are reported. Convective precipitation events (thunderstorms) tend to produce shorter duration storm events than orographic precipitation. Duration, intensity, and frequency of rainfall events are important to flood prediction. Short duration precipitation is more significant to flooding within small drainage basins.The most important upslope factor in determining flood magnitude is the land area of the watershed upstream of the area of interest. Rainfall intensity is the second most important factor for watersheds of less than approximately 30 square miles or 80 square kilometres. The main channel slope is the second most important factor for larger watersheds. Channel slope and rainfall intensity become the third most important factors for small and large watersheds, respectively.Time of Concentration is the time required for runoff from the most distant point of the upstream drainage area to reach the point of the drainage channel controlling flooding of the area of interest. The time of concentration defines the critical duration of peak rainfall for the area of interest. The critical duration of intense rainfall might be only a few minutes for roof and parking lot drainage structures, while cumulative rainfall over several days would be critical for river basins. Downslope factors
Water flowing downhill ultimately encounters downstream conditions slowing movement. The final limitation in coastal flooding lands is often the ocean or some coastal flooding bars which form natural lakes.