Originally Posted by Rosiemac
No i couldn't, plus it's against the law in the UK
Not as far as I know it isn't. It is quite a confusing issue, because there are several pieces of legislation covering different areas:
It is illegal to kill any animal inhumanely (Animal Cruelty)
It is illegal to kill any domestic animal without the consent of the owner, unless there is a court order (such as under the Dangerous Dogs Act) or where it is necessary to end suffering and the owner cannot be found, or where an animal poses a threat to public safety - euthanasia in these cases can be carried out by a veterinary surgeon, RSPCA officer, or trained Police Officer.
It is illegal to kill (and in some cases even to approach or in any way interfere with) any protected native species (Wildlife Protection Act)
It is illegal to slaughter cattle or sheep for consumption outside of a licenced and inspected premises (Meat Hygiene Regulations for the purpose of BSE/scrapie control)
Various bloodsports are illegal under Animal Cruelty legislation
It is not illegal to kill pest species or invasive species, this can include the use of ingested poisons, gases, traps, and guns - in some cases this requires a licence, but domestic infestations may be dealt with by the homeowner.
It is not illegal to hunt using guns (where a gun licence is obtained and outside of breeding seasons), birds of prey, or to fish, as long as you have the landowner's permission, otherwise it is poaching which is illegal (theft of property and trespass, nothing to do with animal welfare!)
It is not illegal to kill your own pigs and chickens for consumption, as long as it is done humanely
It is not illegal to euthanise your own pet, although if the RSPCA found out you may have to prove to a court that it was necessary to prevent suffering and that a humane method was used ie. that getting to a vet would have seriously prolonged suffering. Where this is not the case and a vet was within reach or there was no suffering to prevent you could expect to be prosecuted.
It is not illegal to kill any animal to protect your own safety ie. if attacked, although you may need to prove to a court that it was necessary to go that far.
ETA: Not that I'd be able to bring myself to do it I am sure in the vast majority of situations anyway.