One of the laws which all veterinary surgeons in the UK are bound by is the prescribing cascade. The purpose of this is to ensure that medications used are the safest and most effective possible, however, it is also one of the reasons that medication for animals may appear to be more expensive than that for humans. Vets must use a medication which is authorised in the UK for the species and condition treated unless there is no product available, or a good medical reason for not doing so (finance is not considered to be a valid reason legally). Human generic products cannot be used if there is a formulation that is licensed for use in animals. If there is no suitable product, the vet may prescribe a product as close to the top of the following cascade as possible.
- A medication which is authorised in the UK for a different condition in the same species, or a medication which is licensed for the same condition but in a different animal species.
- A medication which is authorised in the UK for human use, OR a veterinary medicinal product which is not authorised in the UK but is authorised for animal use in another member state
- A specially prepared medication prescribed by the vet and prepared by a vet or pharmacist.