title: Pain assessment in animal models: do we need further studies?
abstract: In the last two decades, animal models have become important tools in understanding and treating pain, and in predicting analgesic efficacy. Although rodent models retain a dominant role in the study of pain mechanisms, large animal models may predict human biology and pharmacology in certain pain conditions more accurately. Taking into consideration the anatomical and physiological characteristics common to man and pigs (median body size, digestive apparatus, number, size, distribution and communication of vessels in dermal skin, epidermal-dermal junctions, the immunoreactivity of peptide nerve fibers, distribution of nociceptive and non-nociceptive fiber classes, and changes in axonal excitability), swines seem to provide the most suitable animal model for pain assessment. Locomotor function, clinical signs, and measurements (respiratory rate, heart rate, blood pressure, temperature, electromyography), behavior (bright/quiet, alert, responsive, depressed, unresponsive), plasma concentration of substance P and cortisol, vocalization, lameness, and axon reflex vasodilatation by laser Doppler imaging have been used to assess pain, but none of these evaluations have proved entirely satisfactory. It is necessary to identify new methods for evaluating pain in large animals (particularly pigs), because of their similarities to humans. This could lead to improved assessment of pain and improved analgesic treatment for both humans and laboratory animals.
authors.affiliation: Anaesthesia and Intensive Care, University of Pavia, Pavia, Italy.
authors.forename: Carmelo
authors.initials: C
authors.lastname: Gigliuto
authors.affiliation: Pain Therapy Service, Fondazione IRCCS Policlinico San Matteo, Pavia.
authors.forename: Manuela
authors.initials: M
authors.lastname: De Gregori
authors.affiliation: ISAL Foundation, Institute for Research on Pain, Torre Pedrera, Rimini, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Malafoglia
authors.affiliation: ISAL Foundation, Institute for Research on Pain, Torre Pedrera, Rimini, Italy.
authors.forename: William
authors.initials: W
authors.lastname: Raffaeli
authors.affiliation: Department of Anaesthesia, Intensive Care and Pain Therapy, Azienda Ospedaliera Universitaria Parma, University of Parma, Parma, Italy.
authors.forename: Christian
authors.initials: C
authors.lastname: Compagnone
authors.affiliation: Department of Molecular Medicine, Center for Tissue Engineering (CIT), INSTM UdR of Pavia, University of Pavia, Pavia, Italy ; Department of Occupational Medicine, Ergonomy and Disability, Laboratory of Nanotechnology, Salvatore Maugeri Foundation, IRCCS, Veruno, Italy.
authors.forename: Livia
authors.initials: L
authors.lastname: Visai
authors.affiliation: Dipartimento di Chimica, Materiali e Ingegneria Chimica 'G Natta' and Unità di Ricerca Consorzio INSTM, Politecnico di Milano, Milan, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Petrini
authors.affiliation: Laboratory of Transplant Immunology/Cell Factory, Fondazione IRCCS Policlinico "San Matteo", Pavia, Italy.
authors.forename: Maria Antonietta
authors.initials: MA
authors.lastname: Avanzini
authors.affiliation: Department of Health Science, University Magna Grecia of Catanzaro and Centro del Farmaco, IRCCS San Raffaele Pisana, Roma, Italy.
authors.forename: Carolina
authors.initials: C
authors.lastname: Muscoli
authors.affiliation: University of Pavia, Department of Surgical, Clinical, Paediatric and Diagnostic Science, General Surgery 1, IRCCS Fondazione Policlinico San Matteo, Pavia, Italy.
authors.forename: Jacopo
authors.initials: J
authors.lastname: Viganò
authors.affiliation: University of Pavia, Department of Surgical, Clinical, Paediatric and Diagnostic Science, General Surgery 1, IRCCS Fondazione Policlinico San Matteo, Pavia, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Calabrese
authors.affiliation: University of Pavia, Department of Surgical, Clinical, Paediatric and Diagnostic Science, General Surgery 1, IRCCS Fondazione Policlinico San Matteo, Pavia, Italy.
authors.forename: Tommaso
authors.initials: T
authors.lastname: Dominioni
authors.affiliation: Pain Therapy Service, Fondazione IRCCS Policlinico San Matteo, Pavia ; Department of Clinical, Surgical, Diagnostic and Paediatric Sciences, University of Pavia, Pavia, Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Allegri
authors.affiliation: University of Pavia, Department of Surgical, Clinical, Paediatric and Diagnostic Science, General Surgery 1, IRCCS Fondazione Policlinico San Matteo, Pavia, Italy.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Cobianchi
keywords: experimental model; pain assessment; translational research