Studies are conducted in adult male and female Sprague Dawley rats (Envigo) in an AAALAC-accredited facility with approval from an Institutional Animal Care and Use Committee, and implemented in accordance with the Guide for the Care and Use of Laboratory Animals 8th Edition (National Research Council, 2011) with standards set by the National Institutes of Health.

Experimental procedure

A change in normal weight bearing of the paws in rodents is a translatable measure of limb pain and or joint pain/instability. This test, devoid of evoked stimulation or restraint, measures the changes in postural equilibrium in rodents by assessing their weight distribution on each of their 4 paws (Philpott et al., 2017).

Rats are placed in the Dynamic Weight Bearing Instrument 2.0 (Bioseb). The acquisition procedure starts after a rat is placed in the chamber (Figure 1). Following a 10 s latency, data are captured in real-time over a period of 180 s. Using the Dynamic Weight Bearing 2.0 software (Bioseb), the following data are summarized for each individual rat capturing: hind paw weight bearing (g), hind paw surface area on sensor pad (mm2), and hind paw time on surface pad (s).

Dynamic weight bearing measurement
Figure 1: representation of the dynamic weight bearing instrument, composed of a chamber in which the animal is confined, a sensor pad on which the animal can move, and a high-resolution camera enabling verification of the scoring.


Philpott HT, O’Brien M, McDougall JJ (2017). Attenuation of early phase inflammation by cannabidiol prevents pain and nerve damage in rat osteoarthritis. Pain, 158 (12): 2442-2451. PMID: 28885454 DOI: 10.1097/j.pain.0000000000001052

National Research Council (2011). Guide for the Care and Use of Laboratory Animals: Eighth Edition. Washington, DC: The National Academies Press

The rat schematic was provided by Servier Medical Art (smart.servier.com).

This work was conducted by PsychoGenics Inc. (Paramus, NJ) in collaboration with PSPP, NINDS, NIH under contract # 75N95019D00026