Directive 2010/63/EU of the European Parliament and of the CouncilShow full title

1. Mild:

(a)

administration of anaesthesia except for the sole purpose of killing;

(b)

pharmacokinetic study where a single dose is administered and a limited number of blood samples are taken (totalling < 10 % of circulating volume) and the substance is not expected to cause any detectable adverse effect;

(c)

non-invasive imaging of animals (e.g. MRI) with appropriate sedation or anaesthesia;

(d)

superficial procedures, e.g. ear and tail biopsies, non-surgical subcutaneous implantation of mini-pumps and transponders;

(e)

application of external telemetry devices that cause only minor impairment to the animals or minor interference with normal activity and behaviour;

(f)

administration of substances by subcutaneous, intramuscular, intraperitoneal routes, gavage and intravenously via superficial blood vessels, where the substance has no more than mild impact on the animal, and the volumes are within appropriate limits for the size and species of the animal;

(g)

induction of tumours, or spontaneous tumours, that cause no detectable clinical adverse effects (e.g. small, subcutaneous, non-invasive nodules);

(h)

breeding of genetically altered animals, which is expected to result in a phenotype with mild effects;

(i)

feeding of modified diets, that do not meet all of the animals’ nutritional needs and are expected to cause mild clinical abnormality within the time-scale of the study;

(j)

short-term (< 24h) restraint in metabolic cages;

(k)

studies involving short-term deprivation of social partners, short-term solitary caging of adult rats or mice of sociable strains;

(l)

models which expose animals to noxious stimuli which are briefly associated with mild pain, suffering or distress, and which the animals can successfully avoid;

(m)

a combination or accumulation of the following examples may result in classification as ‘mild’:

(i)

assessing body composition by non-invasive measures and with minimal restraint;

(ii)

monitoring ECG with non-invasive techniques with minimal or no restraint of habituated animals;

(iii)

application of external telemetry devices that are expected to cause no impairment to socially adapted animals and do not interfere with normal activity and behaviour;

(iv)

breeding genetically altered animals which are expected to have no clinically detectable adverse phenotype;

(v)

adding inert markers in the diet to follow passage of digesta;

(vi)

withdrawal of food for < 24h in adult rats;

(vii)

open field testing.