FOI - Information request on Librela
Published 19 November 2025
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ATI1100 Request
UK reports of a side effect of Horner’s syndrome in dogs after Librela use.
Our reply
All medicines whether for human or animal use come with risk, and the benefits of use in wider populations need to outweigh the potential risks. Information on adverse events that have been known to occur following administration of a particular product are summarised in sections 3.6/4.6 of the Summary of Product Characteristics (SPC). The SPC is a document describing the properties and the officially approved conditions of use of a medicine. The SPC and associated product information are updated as new information is available, and the latest version of an SPC can be found on our publicly available Product Information Database. It is important for veterinary professionals to ensure that this information is reviewed, and any risks discussed with the animal owner or keeper, prior to administering the product. A rolling 6-month list of Summary of Product Characteristic (SPC) changes for veterinary medicines can be found on the monthly medicines update page Vet practice & supply.
Pharmacovigilance updates are published on gov.uk at https://www.gov.uk/guidance/urgent-safety-updates-for-veterinary-medicines; this also includes any updates involving non-veterinary medicines used in animals. To receive these pharmacovigilance updates via email, please click on the ‘Get emails about this page’ button.
All adverse events submitted to the VMD have their clinical signs coded using the Veterinary Dictionary for Drug Regulatory Activities (VeDDRA).
In our databases we have 9 adverse event reports occurring in the United Kingdom in dogs following administration of Librela containing the VeDDRA Preferred Term ‘Horner’s syndrome’.
The number of adverse event reports includes reports:
- where more than one product was used
- when the product was used off-label, that is using a medicine in a way that is not specified on the product’s label, including prescribing of unauthorised medicines following the cascade
- where the reporters, medical professionals or MAH did not consider an association between the product administration and the adverse event to be likely
- where, on further evaluation, there were other reasons for the adverse reaction occurring such as underlying illnesses or an alternative cause for the clinical signs seen
Evaluation of adverse event reports is dependent on the accuracy and quality of data received within adverse event reports from veterinary professionals and animal owners.
Although adverse event report information can be useful to provide a general overview of a VMP, it is important for any clinical decisions regarding the use of a VMP to be based on a risk/benefit discussion specific to the animal or group of animals being administered the VMP. An overall frequency of an adverse event occurring for a VMP does not reflect the actual risk for an individual animal, as there are many individual factors that may contribute to the likelihood of an adverse event occurring.
Data published by the VMD are not subject to independent verification and the VMD does not guarantee their accuracy. Figures may be different to those provided by different regulatory authorities, pharmaceutical companies, and other authorities within the United Kingdom.