Some drugs used to treat horses will be veterinary licensed. This means they will have been vigorously tested for safety, qualify, and efficacy (ie. they do what they are expected to do in the majority of horses eg, relieve pain).
The test results are looked at by the veterinary medicine directive and if approved, the drug may be granted a license and categorised. They could for example, be categorised as general sales list such as some wormers, or as only available under veterinary direction (POM-V) eg. some antibiotics or pain killers.
Unfortunately, there are many circumstances where horses require treatment and there is no licensed product available, for example, there are no licensed eye treatments, shampoos or creams for horses. Therefore, it is extremely common for equine vets to prescribe dog or cattle drugs to treat horses, or even use human prescription drugs.
These are all known as unlicensed products and have not undergone vigorous testing in the horse. In this instance, application of such a product is usually based on known use in the horse, advice from other vets (sometimes abroad), or our own previous experience of the product. Drug companies will not usually be held responsible for adverse reactions of unlicensed products when used in the horse.
If your horse is prescribed an unlicensed product, you may be asked to read and sign a statement such as the one below:-
I understand that …………... is a product which is not authorised / licensed for use in horses / donkeys, but is acknowledged as a product useful in the treatment of ……………. I have also been made aware of the possibility of side-effects (some of which may be unknown) and of the precautions related to its administration. In accepting its use for ……………I accept any attendant risks.
I have read and understood this form. I am over 18 years of age.