Some procedures are more likely to involve animals experiencing ‘severe’ physical pain, psychological distress, or feelings such as ‘sickness’ or nausea. This includes control groups in some vaccine studies, or ‘models’ of diseases that cause high levels of suffering in clinical cases. Examples of potentially severe procedures are listed on pages 8 to 9 of the European Commission report on prospective severity classification. More examples are listed below, based on the scientific literature and discussions with scientists, animal technologists and veterinarians working in academia and industry.

Note: these are guidance only; actual severity will depend upon experimental protocols and the efforts made to refine these.


Batch potency testing of vaccines (where control animals experience ‘severe’ disease symptoms) and other biologics e.g. botulinum toxin, for regulatory purposes

Studies involving infectious disease models, including the development of vaccines or other treatments, where animals may experience ‘severe’ disease symptoms

Various tests involved in regulatory toxicology, including ecotoxicology, especially where animals may become moribund or die

Monoclonal antibody production using the mouse ascites method – NB this method has not been used in the UK since 2012 but is still used elsewhere in the world

Some cancer models – involving large tumours, resection, bone metastasis, brain tumours, pancreatic tumours

Some heart disease models – myocardial infarction induction; monocrotaline (MCT)-induced pulmonary arterial hypertension; transverse aortic constriction/banding

Multi-organ failure models

Demyelination of the central nervous system (CNS)

Models of motor neurone disease (MND)

Spinal cord injury models

Neuroscience studies using non-human primates, involving the cumulative effects of numerous surgeries, regular and long periods of restraint, and/or fluid or food control

Tamoxifen as an inducer of gene function

Irradiation with reconstitution of bone marrow

Cerebral malaria in rodents

Pancreatitis models

Case Studies

Mouse model of amyotrophic lateral sclerosis (ALS)

Mouse model of amyotrophic lateral sclerosis (ALS)

Experimental Autoimmune Encephalomyelitis (EAE)

Mouse cuprizone model of demyelination

Fungal infection in mice

Fungal infection in mice

Rheumatoid arthritis

Mouse models of rheumatoid arthritis


Avoiding and reducing severe suffering helps to fulfil legal requirements, reduce ethical concerns and improve scientific quality – this website will help you to achieve this.

Practical ways to reduce or avoid severe suffering include: