The Cascade is a long-standing legal flexibility providing a rational balance between the legislative requirement for veterinary surgeons to prescribe and use authorised veterinary medicines where they are available, and the need for professional freedom to prescribe other products where they are not. It is intended to increase the range of medicines available for veterinary use.

Animal species may have many physiological differences from humans and from each other. As a result they each may react differently to medicines. The authorisation system for veterinary medicines requires a product to have proven quality and effectiveness and, most importantly, safety for the animal, the user (vet, farmer, pet owner etc.), the environment and, for food animals, the consumer of animal produce. This assurance has to be provided for each species and each indication on the label.

In addition, animal medicines containing the same active ingredient as human medicines may be formulated differently. For instance, the formulation needs to ensure they are properly absorbed through the gut (which, for example, is rather shorter in a cat than a human). Human medicine formulations may contain different excipients or have different bioavailability from veterinary medicines. Therefore, using a product which is not authorised for animals increases the risk of harm to them.

In addition, the cost of developing a medicine for animal use is high and can involve much research and many tests not carried out for human medicines.

In order for animal medicine companies to be encouraged to continue to invest further in Research and Development for new medicines in the veterinary sector, vets must use veterinary authorised products in preference to human licensed products.

It is important to address the potential confusion with the use of the word “generic”. Authorised veterinary generics exist legitimately which can be used by vets as other authorised animal medicines. However, human generic medicines that are similar to the authorised veterinary medicines may not be used unless there is no suitable veterinary medicine available.

The Cascade provides a legal mechanism allowing veterinary surgeons to use their clinical judgement to prescribe a suitable medicine where no authorised medicine exists. Use and prescription by vets of human generic medicines where a suitable veterinary product is available is a criminal offence and contrary to the RCVS Guide to Professional Conduct.

Vets remain entirely responsible for the treatment of animals under their care; use of a medicine under the cascade should be capable of being supported by clear auditable clinical evidence to justify the vet’s decision.

If there is no medicine authorised in the UK for a specific condition, the veterinary surgeon responsible for treating the animal(s) may, in order to mitigate unacceptable suffering, treat the animal(s) in accordance with the following sequence:

(a) a veterinary medicine authorised in the UK for use in another animal species or for a different condition in the same species; or, if there is no such product

(b) either

(c) a medicine prepared extemporaneously, by a vet, pharmacist or a person holding an appropriate manufacturer’s authorisation.

For food-producing animals the following additional conditions apply:

A medicine prescribed in accordance with the cascade may be administered by the prescribing vet or by a person acting under their direction. Responsibility for the prescription and use of the medicine remains with the prescribing veterinary surgeon. Where veterinary surgeons write prescription should contain a statement advising that this is the case.

For further information, please see the VMD’s Veterinary Medicines Guidance Note 13, “Guidance note on the use of the cascade”, available from www.vmd.defra.gov.uk

Animals need medicines to help prevent disease and to help treat them if they do fall ill. All species deserve the benefit of medicinal products which have been specifically developed and authorised for their treatment. The cascade ensures this happens wherever possible, but also gives flexibility for veterinary surgeons to use their clinical judgement to prescribe a medicine where no veterinary authorised medicine exists.