Species & Model Selection

Species & Model Selection

Selection of species and animal model to use can contribute to reduction because some animal models can minimize variation in the experiment and the numbers of animals needed.

Factors contributing to species and animal model selection include scientific objectives, availability, regulatory requirements, and public concern. In some cases, the typical model in the field must be used and there is limited flexibility to consider others.

However, a new literature search should always be undertaken to:

  1. determine or confirm the best species and model for the scientific objective
  2. to find the most recent Three Rs information relating to the species and planned procedures

Reduction and Species Selection

  • Use the most appropriate / well-characterized species to improve the quality of the information collected, and avoid the need to repeat a study
  • Use pilot studies to demonstrate that the proposed species is fit for the scientific purpose
  • Use larger animals when it may decrease the overall number of animals that must be used to obtain sufficient quantities of blood and tissue
  • Use species with larger litter sizes if it means fewer animals will be used when infants/newborns/neonates are the experimental unit

Reduction and Model Selection

  • Use isogenic or genetically identical animals (inbred strains and F1 hybrids) to have less experimental variability than would occur if outbred strains are used
  • Ensure model has been validated and shown to meet the objectives of the research and/or be predictive of the endpoint of interest
  • Ensure model has been fully characterized so that all aspects of the animal's life cycle and their potential impact on the experiment are understood (for example, to ensure the animal will survive long enough to complete the experiment, or whether the rapid growth of a young animal is appropriate to model an adult human)
  • Ensure model is being continuously improved to decrease variability and improve it's predictivity

This section has been adapted from the National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs).

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