Veterinary Practice Records UK
There is the need to keep a record of the proof of purchase of all veterinary medicines bought for farm animals (including horses) treated.
Any person required to keep a record must retain that record for a period of five years following the administration or other disposal of the product.
Citations and References
The Veterinary Medicines Regulations 2013 http://www.legislation.gov.uk/uksi/2013/2033/made