The British Small Animal Veterinary Association recognises that the “Cascade” provides a rational balance between the legislative requirement for veterinary surgeons to prescribe and use authorised veterinary medicines when available, and the application of professional judgment to prescribe other medicines when they are not.

The BSAVA support the continued use of the Cascade because the current range of licensed products does not enable veterinary surgeons to effectively treat the wide range of conditions in all the species commonly encountered in small animal practice. Restriction in the use of drugs through the Cascade would lead to animal welfare problems and the inability to treat a wide range of diseases, particularly in species for which there are few licensed medicines.

Although it is not a legal requirement for veterinary surgeons to report adverse events (AEs) to medicines prescribed under the Cascade, the BSAVA would strongly recommend that this is done so that information on adverse events can be collected and made public. Reports of adverse events can be made through the SARRS yellow card scheme or online at

Background information

The principle of the Cascade is that, if there is no suitable veterinary medicine authorised in the UK to treat a condition, the veterinary surgeon responsible for the animal may, in particular to avoid causing unacceptable suffering, select a treatment for the animal in accordance with the following sequence:

1. A veterinary medicine authorised in the UK for use in another animal species or for a different condition in the same species.
2. If there is no such product, either
a)    a medicine authorised in the UK for human use, or
b)    a veterinary medicinal product (VMP) not authorised in the UK but authorised in another Member State (MS) for use in any animal species (in the case of a food-producing animal the medicine must be authorised in a food producing species) in accordance with an import certificate issued by the VMD.

If there is no such product, the last option is a medicine prescribed by the veterinary surgeon responsible for treating the animal and prepared extemporaneously by a veterinary surgeon, a pharmacist or a person holding an appropriate manufacturer’s authorisation. In exceptional circumstances, medicines may be imported from Third countries through the VMD’s import scheme.

When considering using a medicine under the Cascade a veterinary surgeon should take note of the guidance from the RCVS which states that:

The decision to use a medicine which is not authorised for the condition in the species being treated where one is available should not be taken lightly or without justification. In such cases clients should be made aware of the intended use of unauthorised medicines and given a clear indication of potential side effects. Their consent should be obtained in writing. In the case of exotic species, most of the medicines used are unlikely to be authorised for use in the UK and owners should be made aware of, and consent to, this from the outset.


BSAVA Scientific Committee
BSAVA Council Meeting 2013
Background information updated June 2016

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