The Pharmacovigilance Unit at the Veterinary Medicines Directorate (VMD) is responsible for the monitoring of adverse event reports for veterinary medicines throughout the UK. Adverse event reports are received from veterinary surgeons, animal owners and directly from Marketing Authorisation Holders (MAH).

Over the past year, the VMD has received an increased number of reports of suspected lack of efficacy for Somulose Solution for Injection (secobarbital and cinchocaine), a product which was first authorised in 2004. Lack of efficacy involving an agent used for the purposes of euthanasia, particularly in large animals, can have significant safety implications for the person administering the product. It also has welfare implications for the animal and potential emotional implications for the owners involved.

On reading some of the case histories, it is clear that not all veterinarians are aware of the warnings in the Summary of Product Characteristics (SPC). For large animals, it is important that a jugular catheter is used and the product is administered over a period of 10 to 15 seconds. The VMD would like to remind veterinary surgeons to refer to the SPC, in particular, section 4.4:  special warnings; which states “Rarely, horses may show resistance to euthanasia and prior use of sedation should be considered in each case (see also under section 4.9). It is always advisable to have an alternative method of euthanasia available.” Furthermore, due to the ambulatory nature of equine veterinary work, it is also important to ensure that the product is stored correctly in vehicles; the SPC states “Do not store above 30ºC. Do not refrigerate or freeze. Protect from frost."

A copy of the SPC for Somulose can be obtained from the VMD product information database via the following link:

All suspected adverse events should be reported to the MAH or the VMD. An interactive reporting form can be completed and submitted online via the VMD website at the following link: