Advisory report: Careful assessment of methods for identification and genetic characterization

Toe clipping (distal phalanx clipping) and ear notching are commonly used methods for the identification and genetic characterisation of genetically modified rodents. However, ear and toe clipping as methods of rodent identification is a contentious issue in the context of animal welfare. Toe clipping in particular encounters resistance.

In 2016, ZonMW, at the request of the Minister of Economic Affairs, conducted a study on the use of toe clipping. In this study, ZonMW identified several methods that are suitable for either genotyping or identification of laboratory animals. At the time, there was no better alternative for genotyping and identification of young animals than toe clipping.

In 2018, the then Minister of Agriculture, Nature and Food Quality asked the NCad to reconsider the possibility for phasing out toe/distal phalanx clipping as an identification method, provided an equivalent alternative was available. In 2020, we issued an advisory report in response to this request.

In this advisory report, we present an overview of all existing methods for identification and characterisation, as along with a list of alternatives. This overview serves as an easily accessible guide for selecting the most appropriate identification and characterisation methods.

We recommended that all these methods be carefully considered before a choice is made. For example, by reassessing this decision for each research design, taking into account aspects such as violations of integrity, violations of welfare, and improvements in the quality of science.

We also advised the Ministry of Agriculture, Nature and Food Quality and the Ministry of Education, Culture and Science to initiate a specific project aimed at developing combinations of sustainable, non-invasive identification and characterisation methods, in which violating the integrity and welfare of the animal is eliminated or minimised. We also recommended more research into innovative techniques for the identification and characterisation of animals, such as ‘individual face recognition’ and DNA isolation and analysis techniques.