From Mr Myc Riggulsford Sir: Your article "ALF bomber gets 14 years" (20 December) and the open letter from Celia Hammond ("Dear Michael Howard", 21 December) highlight the problems facing our doctors and scientists carrying out life-saving medical and veterinary research in the face of the threats and intimidation from animal rights "fanatics".

The behaviour of people such as Keith Mann, who has just received a 14-year sentence for bomb-related activities, serves only to stifle the public and private discussions that our charities are seeking in order to improve animal welfare and make sure that the use of live animals for research is minimised.

These people have no regard for animal welfare, as previous attacks on veterinary centres and attempts to disrupt veterinary research have shown. Nor have they any regard for human life: blowing part of the hand off a child in a pushchair in Bristol, sending live explosives to charity workers, and endangering the lives of firemen through irresponsible arson attacks.

It is heartening to hear the condemnation of such cowardly activity by genuine animal welfarists, and all our doctors and vets should be encouraged by knowing that their humanitarian attempt to help others, through better understanding of disease is fully supported by our animal and medical charities, patients, families and their friends who have been helped in the past or whose hope lies in future research.

Yours, MYC RIGGULSFORD Director, Research for Health Charities Group Shepton Mallet, Somerset