Christine is epileptic and has seizures two or three times a week. If she did not know when they were going to happen, she would not dare to go out and would be fearful of climbing stairs. But she does know, because her dog, Annie, warns her. She puts her paws on Christine, and tries to lick her face. Christine stops what she is doing and lies down, and soon afterwards she is racked by a fit. "I can't explain it. But Annie can tell when I'm going to have a seizure," she says.

Jackie, in Mansfield, has several severe fits a week, and after collapsing on a main road became fearful of going out. She contacted a charity called Support Dogs, who trained a dog, Sam, to give her warnings of seizures. Now she says her life has changed. "Sam lets me know when a seizure is coming 20 minutes before it happens. If we're in the house, he warns me by barking. If we're in public, he will sit in front of me and stare, remaining rigid like a stuffed animal.

This allows me to find a safe place to have a seizure".

In the 1990s, a vet, Andrew Edney, made a pioneering survey of dogs that give warnings of fits. No particular breed stood out. Dogs of all kinds and ages do it, both male and female. Usually they "herd" the person to safety and encourage him or her to lie down.

When the seizure is taking place, they either stay by the person or seek help. And they are remarkably reliable. As Edney commented, "No dog seemed to get it wrong, one even ignored 'fake' seizure attempts."

How do they do it? No one knows. Perhaps they detect tremors, or subtle smells. But some dogs can do it from a distance, and run in from another room to give a warning. There may be more to it than the usual senses. But whatever the explanation, thousands of people like Jackie and Christine depend for their freedom and safety on dogs with this unexplained ability.

Rupert Sheldrake would like to hear from readers about animals that give warnings of seizures or other emergencies. Email Rupert Sheldrake's researcher, pam@telepet.demon.co.uk with subject heading: Rupert Sheldrake.

Dr Rupert Sheldrake is a biologist and the author of Dogs That Know When Their Owners Are Coming Home, And Other Unexplained Powers of Animals (Arrow, #7.99).

 www.sheldrake.org