MCT Morrison is incorrect to claim that heart operations, transplant surgery and the treatment of diabetes could not have been developed without animal experiments.

Pacemakers and heart valves were delayed in development because of physiological differences between animals they were designed on and humans.

Cyclosporin A inhibits organ rejection and its development was a watershed in the success of transplant operations.

Had human evidence not overwhelmed unpromising evidence from animals it would never have been released.

Diabetes research was held up for decades by animal research until in vitro research isolated insulin.

There is abundant evidence that animal experiments have provided misleading results that, when applied to humans, have proved tragic or fatal.

The recent case of test drug TGN1412 which left two men critically ill shows how misleading animal test data can be.

The drug had been given to monkeys in doses 500 times stronger than the human volunteers.

The real benchmarks of medical progress have relied on non-animal mythologies such as advanced technology, clinical research, human autopsy, epidemiology, in vitro research etc.

Laboratory animals suffer terribly at every stage of their lives.

Most live in overcrowded, factory-farm type conditions. Experiment licences permit the infliction of pain and suffering.

I would like to reassure MCT Morrison that the majority of animal rights activists care for humans as well as animals.

We do not want to see humans suffering because of unreliable animal testing, or animals suffering through unnecessary cruel experiments.

MARILYN HARRISON

Toothill,Swindon