Often humane endpoints are set to prevent an animal exceeding the severity limits assigned to a particular research protocol. The EU Directive classifies procedures as mild, moderate, severe and non-recovery.
Classifications
This classification is done before the study starts and at the end of the study we do a retrospective assessment of what actually happened.
Mild
Procedures on animals as a result of which the animals are likely to experience short term mild pain, suffering or distress. Procedures with no significant impairment of the wellbeing or general condition of the animals e.g. :
- Non-invasive imaging of animals (e.g. MRI) with appropriate sedation or anaesthesia.
- Superficial procedures, e.g. ear and tail biopsies.
- Administration of substances by subcutaneous, intramuscular or intraperitoneal routes.
Moderate
Procedures on animals as a result of which the animals are likely to experience short term moderate pain, suffering or distress, or long-lasting mild pain, suffering or distress. Procedures that are likely to cause moderate impairment of the wellbeing or general condition of the animals e.g. :
- Surgery under general anaesthesia and appropriate analgesia.
- Use of metabolic cages involving moderate restriction of movement over a prolonged period (up to 5 days).
- Models of induction of tumours, or spontaneous tumours, that are expected to cause moderate pain or distress or moderate interference with normal behaviour.
Severe
Procedures on animals as a result of which the animals are likely to experience severe pain, suffering or distress, or long-lasting moderate pain, suffering or distress. Procedures that are likely to cause severe impairment of the wellbeing or general condition of the animals e.g. :
- Toxicity testing where death is the endpoint.
- Irradiation or chemotherapy with a lethal dose without reconstitution of the immune system.
- Models with induction of tumours, or with spontaneous tumours, that are expected to cause progressive lethal disease associated with long-lasting moderate pain, distress or suffering.
Non-Recovery
Procedures, which are performed entirely under general anaesthesia from which the animal shall not recover consciousness.