Refinements to Animal Models for Biomedical Research

This collection includes the manuscripts published in the Special Issue of Animals: Refinements to Animal Models for Biomedical Research [...].

future, the basis for refinements will hopefully shift from less of an empirical mode to more of an evidence-based approach. In turn, there may be stronger justification to standardize aspects of animal care between projects performed at different locations which will improve our capacity to compare results. For example, Kint et al. describe such an approach for the anaesthesia of rats undergoing functional magnetic resonance imaging in this Special Issue [5].
Further consideration of Russell and Burch (1959) and their opinion that refinement may be considered a distinct method of removing inhumanity, focusing on the actual conduct of research and how sentient animals are treated [3]: the indisputable value of anaesthesia and analgesia in refinements in animal experimentation has been acknowledged for some time [12]. Clutton provides a comprehensive Anglocentric history of anaesthetics and analgesics in the refinement of animal experiments in this Special Issue. The importance of anaesthesia as the greatest single advance in humane technique is described along with the role of anaesthetics and analgesics prescribed and administered by appropriately trained people being acknowledged [12]. This comprehensive commentary of Clutton's is thoroughly researched and is a useful resource to understand the scope of progress that has been made in the use of anaesthetics and analgesics in general, but specifically in the care of research animals.
Other publications in this Special Issue provide useful practical contributions to the often sparse evidence for the use of analgesia for animals, relating to the use of transdermal fentanyl patches in rabbits [6] and sheep [9]. The greatest challenge in providing analgesia for animals is pain assessment and, within this book, the utility of pain assessment strategies is also discussed. The use of nociceptive threshold testing in multiple species is described [13] along with the value of facial grimace scales [14,15]. In addition, the quest for an optimal approach to pain assessment in neonatal piglets, in the context of castration, is described [8]. Perhaps the ultimate aim of pain assessment for both individual animals and for groups of animals in analgesic efficacy studies is an objective measurement. Circulating compounds such as inflammatory cells may be useful and Kongara et al. describe quantification of gene expression of peripheral leucocyte inflammatory cytokines in calves undergoing disbudding [16]. This collection of papers describes the evolution of various approaches to pain assessment in animals with constructive commentary on how to exploit their use. Ongoing efforts to develop strategies for pain assessment in animals are necessary until we are able to reliably and consistently identify and interpret signs or markers of pain in animals.
In classic laboratory animal species, the health status of the animal is well documented and understood. Some species, including sheep (and pigs), are not usually bred specifically for research and are often sourced from commercial farming enterprises. Berset et al. present the results of a European survey, which elucidated the importance of health status documentation and monitoring as essential components to refinement in the use of sheep [17]. These authors highlight the frequency and negative impact of pre-existing animal health issues on the research objectives.
A single manuscript on refinements for euthanasia was also included in this Special Issue. The case study explores the use of an irreversible penetrating spring-loaded captive bolt method of euthanasia in guinea pigs with favourable results [7]. This manuscript is a good example of the translation of techniques from one species to another and the collation of preliminary evidence to establish safety and efficacy in a novel species.
The contents of this Special Issue are evidence for the enthusiasm for the concept of refinement across a broad range of species and contexts within biomedical and animal research.
Funding: This work received no external funding.

Conflicts of Interest:
The author declares no conflict of interest.