The Hargreaves Plantar test was first introduced in 1988 by Hargreaves and his colleagues (Hargreaves et al., 1988) as a method for evaluating cutaneous hyperalgesia induced by thermal stimulation in rats. This test is specifically designed to assess thermal pain sensations in designated areas of the plantar surfaces of animals. It has become a widely used tool for examining pain sensitization and responses in subjects recovering from neural injuries and during regeneration. Other apparatuses and assays similar to the Hargreaves Plantar test include the Tail Flick test, Hot-Cold Plate test, and Thermal Gradient test.

The Hargreaves apparatus features chambers with glass flooring where the subject is placed, and a radiant or infrared heat source is directed at the center of the plantar surface from beneath. Each test typically lasts no longer than 35 seconds to prevent tissue damage and ensure the safety of the animals. To maintain the integrity of the heat stimulus, any urine must be cleaned up during trials. The glass flooring reduces heat-sink effects, allowing for more precise application of heat. Unlike other thermal stimulus assessments, the Hargreaves test does not heat the entire plantar surface, thus avoiding the potential confounding effects of heating irrelevant areas and ensuring a more accurate response from the subject.