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Background

The present “Recommendation on the creation and use of score sheets” was drawn up by a working group formed as part of the work of the NRW animal welfare officers in the period from the 2nd to 4th quarter of 2023.

This working group included the elected representatives of the animal house managers and animal welfare officers (Dr. Philip Dammann, Prof. Dr. Gero Hilken, Dr. Matthias Schmidt, Prof. Dr. René Tolba, Dr. Maureen Walberer). The content of the recommendation was discussed and agreed in detail with the representatives of the licensing authority in North Rhine-Westphalia (State Office for Nature, Environmental and Consumer Protection - LANUV) during its preparation and prior to publication. The recommendations are intended to serve as a guide, but do not exclude the possibility of further necessary and application-specific clarification aspects with the approval authority.

In animal experiments, the stress for the laboratory animals must be limited to the absolute minimum. Due to legal regulations at both European and national level, the specific termination criteria must be specified as part of the application procedure for animal experiments ( § 31 para. 1 sentence 2 no. 1d TierSchVersV) and a “score sheet” must be attached (see also application item 1.2.10. in the application for approval (simplified procedure, if applicable) or notification (for decapod crustaceans) of animal experiments NRW, https://www.lanuv.nrw.de/verbraucherschutz/tierversuche/antragsunterlagen).

In principle, the recommendations of the GV-SOLAS, the principles of good veterinary practice and the DFG guidelines for safeguarding good scientific practice apply. Deviations from these recommendations may be scientifically necessary, but must then be justified.

Target Group

This recommendation is intended to serve as a guide for applicants and animal welfare officers when creating and using score sheets.

Important definitions

Stress

Sum of all factors that have a direct or indirect effect on anatomical, physiological, cognitive or emotional states and lead to short-term or permanent pain, suffering (distress, e.g. anxiety) or damage.1

Level of stress

According to EU Directive 2010/631 and the Animal Welfare Experimental Animal Ordinance (TierSchVersV)2 , which has been in force in Germany since 2013, animal experiments must be categorized into different levels of stress. Based on the severity of the individual stresses, their frequency and duration as well as the summation (accumulation) and/or interaction of the individual stresses (in the sense of a mutual influence: e.g. phenotype of a genetically modified line leads to a stronger reaction to a treatment), a maximum overall severity level (“low”, "moderate" or “severe”) is prospectively estimated for the experimental project, which corresponds at least to the highest individual severity level (prospective stress assessment). This degree of severity is reviewed by the §15 Commission and the LAVE (former LANUV) as the approval authority in NRW as part of the approval procedure for the animal experiment. In the annual laboratory animal report, the actual maximum degree of exposure of each individual animal is reported.

Current stress assessment

Assessment of the stress for individual animals at the current time in the course of the trial or in breeding operations requiring approval.3

Termination criteria / humane endpoint / stress limit

The limitations on the pain and suffering that an experimental animal may suffer, within the framework of the scientific endpoints that must be achieved.4 They serve to define criteria for termination of the experiment or the experiment-specific humane endpoint.2

Trial termination

Immediate termination of the ongoing experiment for the animal concerned and examination of whether euthanasia is necessary.3 A termination of the experiment does not necessarily mean euthanasia of the animal, but may also require interventions such as the use of (experiment-influencing) analgesia or discontinuation of a drug.

Objective of score sheets

It must be anticipated at the time of application, i.e. before the start of the experiment, which specific stresses are expected for the laboratory animals and the indispensability of these stresses must be scientifically justified. In addition, the point at which these stresses can no longer be tolerated must be defined (termination criteria / human endpoint / stress limit). This stress limit must be set as low as possible. The score sheet must be used to recognize when the approved stress limit has been reached and measures to be taken must be initiated. For this purpose, instructions must be formulated that immediately reduce the stress on the animal when the expected stress limit is reached, e.g. through suitable therapeutic or refinement measures. If this is not possible, the experiment must be terminated for the animal concerned (= trial termination).1 If an increase in the approved stress limit is essential to achieve the trial objective, this change must generally be applied for from the approval authority. The exact procedure must be agreed individually with the LAVE (former LANUV.

What can score sheets achieve?

  • They are used to define criteria for terminating an experiment or the trial-specific humane endpoint, as well as the stress limit that must be tolerated in order to achieve the trial objective. Death as the endpoint of a procedure should be avoided as far as possible and replaced by early and painless endpoints.2 Furthermore, refinement measures are defined in score sheets in order to reduce the stress for animals in the experiment.
  • They are intended to help assess, based on defined criteria, whether a trial-specific human endpoint has been reached and whether it is therefore necessary to terminate the trial.
  • They should help to recognize stress in the animals at an early stage through defined observation intervals and consistent observation parameters and to react appropriately. The observation intervals must take into account the current stress assessment and be selected or adjusted accordingly.
  • They must be written in such a way that all persons involved in an experimental project can apply them equally in order to strive for the greatest possible objectivity. They must therefore be both comprehensible and clearly formulated and contain unambiguous instructions for action.
  • They can be used to check and, if necessary, correct the prospective stress assessment both during the ongoing trial and retrospectively.

Limitations of score sheets

  • Without validation, score sheets are not suitable for determining the actual stress level of the individual animal.5 This requires an expert diagnosis of the animal on site, in which all real stresses occurring are recorded for an overall picture of the animal, taking into account the circumstances under which they occur. Score sheets must be continuously reviewed and, if necessary, adjusted during the course of a test in order to record the actual stresses occurring in an animal as objectively as possible.3
  • Due to the subjective human observation, which is dependent on the experience of the examiner (interobserver variability), different diagnostic findings can occur (e.g. the score for assessments of external appearance is different).
  • Despite maximum care, unforeseeable events and spontaneous deaths can occur. In such cases, a competent person must be consulted and, if possible, the cause of death must be determined so that further measures can be taken.

What are the contents of score sheets?

1. Listing of the potential signs of stress to be expected in the experiment and their weighting (e.g. via a points system) and measures to be taken when a certain number of points or criteria is reached, as well as their duration.

2. Definition of termination criteria or humane endpoints: The aim is to avoid death as the endpoint of a procedure whenever possible and to replace it with early and preferably painless endpoints.2 Termination criteria / humane endpoints are to be selected in such a way that exceeding the stress limit essential for achieving the experimental objective is prevented as far as possible. Adequate endpoints must be defined depending on the experiment and animal model.

3. Reaching a termination criteria or a total score that leads to termination of the experiment does not necessarily equate to severe stress!

4. Definition of termination of the experiment: Immediate cessation of the ongoing experiment for the animal concerned and examination of whether euthanasia is necessary. Termination of the experiment does not necessarily mean euthanasia of the animal, but may also require interventions such as the application of analgesia (which influences the experiment) or the discontinuation of a drug.

5. Definition of control intervals/scoring intervals: Determination of sensible times for monitoring the animal or the experiment and their frequency, also taking into account the current stress assessment.

6. Definition of the frequency of determination of (in particular trial-) specific parameters, which may be collected in deviation from the scoring intervals (e.g. intervals for body weight determination or tumor measurement, etc.)

7. Definition of suitable husbandry, care and/or therapeutic measures when specified symptoms occur.

8. Definition of specific instructions for action: Instructions for action must be formulated in such a way that when the previously defined stress limit is reached, refinement measures are taken to reduce the stress. If this is not possible, the experiment must be terminated for the animal concerned. Criteria that require immediate humane euthanasia must be clearly defined in the score sheet as instructions for action.

9. Determining the procedure in the event of unexpected stress (e.g. calling in a vet)

What needs to be considered when using score sheets?

What must be observed when using score sheets in experimental projects?

  • The score sheet approved by the competent authority as part of the animal experiment application must be used without restriction in the course of the experiment.
  • Irrespective of the specified termination criteria, the experiment must be terminated and the animal concerned killed in accordance with animal welfare requirements if, in the opinion of the animal welfare officer, this is essential for animal welfare reasons due to the condition of the animal.
  • In the event of ambiguities in the application of the approved score sheet, the investigator must reach a decision with the animal welfare officer and/or the responsible veterinarian.
  • If unexpected symptoms occur that have not been taken into account in the score sheet, the responsible veterinarian and/or the responsible animal welfare officer must be consulted and the score sheet adjusted accordingly. This change must be reported to the competent authority.
  • If an increase in the approved prospective stress level is essential to achieve the objective of the experiment, this change must be requested from the approval authority.

References & Download

1 Directive 2010/63/EU of the European Parliament and of the Council of September 22, 2010 on the protection of animals used for scientific purposes, recital (14)


2  Animal Welfare Experimental Animal Ordinance of August 1, 2013 (BGBl. I S. 3125, 3126), last amended by Article 1 of the Ordinance of August 11, 2021 (BGBl. I S. 3570) 


3 Statement from the Committee for Animal Welfare Officers “Possibilities of stress assessment in animal experiments”, February 2020


4 Wallace J. Humane endpoints and cancer research. ILAR J. 2000;41(2):87-93. doi: 10.1093/ilar.41.2.87. PMID: 11417496 


5 Talbot SR et al., Defining body-weight reduction as a humane endpoint: a critical appraisal. Lab Anim. 2020 Feb;54(1):99-110. doi: 10.1177/0023677219883319. Epub 2019 Oct 30. PMID: 31665969.

You can download the “Recommendation for the creation and use of score sheets (NRW Animal Welfare Officer)” here as a PDF document (only available in German).