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Methods which improve animal welfare

Our goals are to ensure that each individual animal within an experiment is experiencing the minimum pain, suffering, distress or lasting harm that is compatible with a meaningful result. Both direct harms (such as pain following an injection) and associated harms (such as altering a social group to equalise experimental group sizes) need to be considered.

Any departure from normal conditions, routine and treatment could contribute to the overall impact of the procedure on the animal. The duration of an experiment is also considered. Examples of refinement include using the least invasive methods for any surgery with appropriate anaesthetics and analgesics, and placing limits on the number of times an individual animal may experience a particular stress. The Babraham Campus Animal Usage Guidelines are reviewed regularly by vets and the AWERB ethical review committee. These advise on certain procedures such as dosage routes, volumes and frequencies, and follow a variety of published good practice guidelines.

The ultimate aim is the continual improvement of an experimental model with the minimal departure from normality. Advance consideration of any likely adverse events, such as a drug reaction or an infection, together with definition of humane end points is essential.

Examples

• Mice are routinely handled using the cupping technique. When mice are transferred between cages this is carried out using hands, or rafts and tubes that are present within the cage, as opposed to picking up by the tail.
• Delivering pain medication in an edible gel to replace injections.
• Use of anaesthetic nose cones during micro-chipping for continued anaesthesia during the microchipping process (when this is required).
• Use of flexible tubes for introducing substances to the stomach (oral gavage). Introducing soft flexible gavage tubes replaced the use of rigid metal tubes which can cause oesophageal damage.
• Refinement blood sampling techniques. For collecting blood from the saphenous vein (in the thigh), refinement of the technique has removed the need for full mouse restraint and body heating for vasodilation. For blood collected from the tail vein (when necessary), we have replaced the use of scalpels with a needle.
• When mice are killed by one of the approved methods (Schedule 1), we are removing the use of carbon dioxide (where mice are killed by a gradual increase in carbon dioxide level) which is aversive to rodents to use methods that reduce animal sufferings, which are cervical dislocation or overdose of anaesthetic.
• Use of the latest technologies in monitoring animal welfare, such as using assessments of lung function in respiratory infection studies, to improve our ability to detect issues at an earlier stage and therefore maintain high levels of welfare. We have refined the technique used in studies of lung function (plethysmography) to reduce the time taken by a third.
• Environmental enrichment is compulsory in animal cages and is varied to suit the occupants. For example, refuges such as cardboard tunnels and elevated rafts are provided, the latter also being of value in case of drinking water leaks.
• Food treats such as seeds may be mixed in bedding to provide interest and all animals are provided with materials to build nests. An ongoing trial is analysing the mouse preference for different nest building materials to improve animal welfare and breeding efficiency.
• Design innovations by a facility manager created the Cell Pad device, which is now internationally distributed as in-cage environmental enrichment, as well as being used in the Institute’s facility.
• Procedure-success monitoring informs technician training and ensures that techniques are performed to a high accuracy.
• Use of heat-pads during embryo transfer surgery to avoid risk of hypothermia and and the use of warm air cabinets to aid animals' recovery.