Burrowing impairments after intraplantar CFA injection unmask spontaneous pain.
Known analgesics (NSAIDs and an anti-NGF antibody) reinstate burrowing performance.
Opioid efficacy is masked by sedative motor impairing side effects.
Burrowing is not driven by an instinct to find shelter or biased by trait anxiety.
Burrowing is an objective read-out for pain in the rat intraplantar CFA pain model.