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Use of medicines Under the prescribing cascade

The Cascade is a risk based decision tree that allows Us, as RCVS registered veterinary surgeons, to use Our clinical judgement in the treatment of Your animal(s) whilst under Our care by deciding which medicine to use, when there is no authorised veterinary medicine available in the UK. This is sometimes referred to as ‘off-label’ use.

For drugs to be licensed they must undergo vigorous testing, which is an important but expensive process. Unfortunately, there are relatively few drugs specifically licensed for horses, which means that we often need to use drugs licensed in other species or in humans. In addition, those medications that are licensed for horses may not be licensed for the indication or route of administration we require. This is particularly true for drugs used in reproduction, for example there are no antibiotics licensed for intrauterine infusion, but clinically we know infusing antibiotics into the uterus is important in the treatment of uterine infection.

There are certain risks involved using medicines off-label due to the different ways drugs may be prepared and the way they may be metabolised by the body. This means drugs may be more harmful in some ways and safer in others, and for this same reason the doses used may vary in different animals and via different routes. It is down to us as veterinary surgeons to use our clinical knowledge and experience to weigh up the risk versus benefit of treatment in each individual case.

In the majority of cases the drugs we choose will have been used previously in a clinical setting many times and will have been proven to be safe and effective, despite not being subject to the same licensing protocols. We endeavour where possible to use licensed drugs to ensure safe and effective treatment.

The cascade tree is as follows, in descending order of suitability:

  • A veterinary medicine authorised in the UK for use in another animal species, or for a different condition in the same species


If there is no such product available we can use, either:

  • a medicine authorised in the UK for human use, or

  • a veterinary medicine not authorised in the UK, but authorised in another European member state for use in any animal species. In such cases the importation of a drug needs to be made under special license issued to us by the Veterinary Medicines Directorate (VMD). Or,

  • a medicine prescribed by the vet responsible for treating the animal and prepared especially on this occasion (also known as a ‘special’) by a vet, a pharmacist or a licensed specials manufacturer. Or,

  • in exceptional circumstances, medicines may be imported from outside Europe under license by the VMD.


Only a horse declared as a non-food producing animal can be treated under the Cascade. This involves both you as the owner, and a veterinary surgeon signing section nine (IX) of the passport, confirming that the horse will not enter the human food chain. All horses under the care of Equine Reproductive Services (UK) Limited will be signed out of the human food chain and so section IX will be signed and by agreeing to this you are agreeing that you are happy for us to use our clinical judgment in the use of the cascade.


Medications which may be utilised off-label by Equine Reproductive Services (UK) including specials and generic compounds/human drugs:


Generic compounds/human drugs







Macrolides & Rifampicin  




Ocular antibiotics



Including: prednisolone, dexamethasone, beclomethasone, hydrocortisone, betamethasone, triamcinolone, methylprednisolone

Ocular antiinflammatory












Pentosan polysulphate




Medications specifically used off-label in reproductive medicine include:

Intrauterine infusions or lavages including:

Saline or Hartman’s solutions

Dimethyl-sulphoxide (DMSO)


Antibiotics (procaine penicillin, gentamicin, ceftiofur)

Progesterone releasing intra-vaginal devices (PRIDs)

GnRH vaccines

Generic or human products used:

Antifungals (clotrimazole, fluconazole, nystatin)





Goserelin (Zoladex)


Specials used:








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