Table 2.

Consequences of uncertainty: How to plan a structured welfare assessment and appropriate monitoring.

Uncertainty Factor	Welfare Assessment Factors (1) Time Points For Assessment	(2) Assessment/Examination Parameters 1	(3) Assessors
Low	Animals are assessed at defined time points, from onset of disease until the end of lifespan; frequency according to expected phenotype, e.g., progression of disease.	Adapt the general welfare assessment scheme according to the clinical signs expected.	Scientist and/or animal caretakers; involve veterinarian or Animal Welfare Officer (AWO) if needed.
Medium	Animals are assessed at time points according to expected onset of disease until the end of lifespan; additional time points before and between expected time points should be defined to recognize unexpected phenotypes (all stages of life course should be covered)	Adapt the general welfare assessment scheme according to the clinical signs expected. Include general welfare criteria, e.g., measurement of body weight to recognize unexpected events as soon as possible, and postmortem examination.	Scientist and/or animal caretakers; involve veterinarian or AWO if unexpected phenotypes occur and for the final assessment of the line. Discuss refinement and degree of severity with veterinarian or AWO.
High	All stages of life course should be covered.	Use the general welfare assessment scheme. Include postmortem examination.	Assessment should be carried out by two experienced persons; involve veterinarian or AWO for ongoing monitoring and for the final assessment of the line. Discuss refinement and degree of severity with veterinarian or AWO.

¹ Assessment should be based on observational parameters and should not involve interventions that may cause additional pain, suffering, or distress. If the characterization of severity of a phenotype requires invasive methods, that should be covered under project authorization.