Multiple procedures
Although a judgement of the severity of a procedure may simply look at the most painful or distressing technique to be applied to the animal, this ignores the overall effect of all of the techniques involved in a research procedure.
Repeated intraperitoneal injections, for example, may result in a greater severity than the ‘mild’ classification that might be applied to a single injection of an appropriate volume of a non-irritant material.
The concept that repeated procedures, or combinations of procedures, can combine to make the overall severity greater is called ‘cumulative suffering’.
When making the retrospective assessment of what an animal experienced during a procedure, a better term than ‘cumulative suffering’, or ‘cumulative severity’ is ’cumulative experience’.
Cumulative experience
Cumulative experience is the sum of all the positive as well as the negative impacts on the health and welfare of an animal over its lifetime.
Positive impacts include refinements to breeding, husbandry or procedures that either directly improve the health and welfare of experimental animals or mitigate the negative impacts of experimental procedures.
Negative impacts include the direct negative impacts of experimental procedures such as pain, fear or hunger. They also include the negative impacts entailed in transport, handling and housing of experimental animals, and the negative impacts arising from complications such as infections or physical injuries.
We need to know a lot more about how these negative and positive effects can interact before we can make good judgements of “cumulative experience”.