Refinement of the Care and Use of Laboratory Ferrets

Abstract

Ferrets (Mustela putorius furo) are a valuable animal model in biomedical research, e.g. for studying human diseases such as influenza. Legislation requires studies using animals to adhere to the principle of the 3Rs, i.e. to replace the use of animals where possible; to reduce the number of animals used without compromising the scientific requirements; and to refine the use of animals. Refinement includes “any approach which avoids or minimises the actual or potential pain, distress and other adverse effects experienced at any time during the life of the animals involved, and which enhances their well-being” (Buchanan-Smith et al., 2005). However, when it comes to refinement of the care and use of laboratory ferrets, there is a knowledge gap, which is also reflected in the limited amount of ferret-specific information in the EU Directive. The studies presented in this thesis are performed with the aim of giving insight into possible ways to refine the care and use of laboratory ferrets, focusing on the value and effect of environmental enrichment and the recognition of pain and other forms of discomfort in ferrets. The value of environmental enrichment for ferrets was assessed using multiple consumer demand studies. The results of these consumer demand studies indicated that ferrets are highly motivated to gain access to a hammock, a water bowl, foraging enrichment and conspecifics, whereas the ferrets showed a low motivation to gain access to balls. Subsequently, the effect of the provision of highly valued and less valued enrichment was assessed using behavioural observations and physiological parameters. Ferrets that were housed in standard conditions showed a greater increase in agonistic behaviour over eight weeks than the ferrets that were housed with (non-preferred or preferred) enrichment. Ferrets that were provided with preferred enrichment showed an increase in social play behaviour and a decrease in rearing behaviour over eight weeks, while the ferrets with non-preferred enrichment and those in standard housing conditions did not. An overview of currently used parameters to assess pain in ferrets was made, using the results of a literature review and owner survey. From this overview, the use of facial expressions, a relatively new measure for the assessment of pain, was identified as being a promising new parameter. Since a so-called grimace scale was not developed yet for ferrets, a Ferret Grimace Scale consisting of five action units (orbital tightening, whisker retraction, nose bulging, cheek bulging and ear changes) was composed. Subsequent evaluation of this grimace scale indicated that mainly the action unit orbital tightening could be used by blinded observers to differentiate ferrets pre- and post- surgery and might therefore be useful for pain assessment in (laboratory) ferrets. Summarising, the results of the studies presented in this thesis show that the care and use of laboratory ferrets can be refined 1) by providing them with hammocks, a water bowl and a foraging ball; and 2) by using the Ferret Grimace Scale to recognise pain.