Researchers determined that the clipping technique, dubbed "clipnosis" or pinch-induced behavioral inhibition, relaxes most cats as long as the clips are placed before a cat has a chance to become too agitated or upset.

In the study, 30 of 31 cats responded positively the first time clips were placed on the scruff of their neck. The positive response tended to improve after repeated clippings over three months, suggesting the technique can be used over the course of a cat's lifetime for such procedures as physical examinations, blood draws, and vaccinations.

The clipping seems to evoke the same scruff response that renders kittens still so their mothers can carry them in their mouths, said senior study author Tony Buffington, professor of veterinary clinical sciences at Ohio State. Even most adult cats will go limp when they are gently grasped by the scruff of the neck, he said.

"Cats generally seemed more content, sometimes even purring, and less fearful during veterinary procedures when clips were used instead of restraint by some other means," Buffington said.

The study appeared in the February 2008 issue of the Journal of Feline Medicine and Surgery.

A host of tests during the clipnosis experiment showed the technique does not cause cats pain.

"It's easy to tell if you're hurting animals because they don't like it when you do things to them that hurt," Buffington said. "When the cats in this study saw the clips, they often would lie down. If the cats were hurt by them, they would have seen those clips and tried to get away. If anything, the effect on them is positive."

The researchers used one or two standard two-inch binder clips in the study and conducted a test to ensure the pressure of the clips would not damage the cats' skin or interfere with blood flow.

"We found that the pressure is no more intense than a blood pressure cuff when it is measuring your blood pressure," Buffington said. Previous research has shown that it would take four to six times more pressure over several hours to cause any damage to a cat's skin. The clips are typically used for only a few minutes at a time.

In the study, the clips were placed directly behind the ears in the middle of each cat's back. A second clip, if used, was placed immediately behind the first.

Several types of clips were analyzed, and the most effective appeared to be those that most closely matched a cat's systolic blood pressure. Buffington designed a clip that Ohio State has patented and is licensing for commercialization.

Cats are good candidates for restraint techniques because they are genetically inclined to be afraid of humans and dogs, their ancestral predators, and might feel competitive around other cats. As solitary hunters, they also don't recognize the existence of any hierarchy that would place humans at the head of a pack. So veterinary visits, where they typically encounter all of these species, can be particularly stressful for cats.

Buffington is an advocate for teaching all new kitten owners how to use the clipnosis technique, and said awareness of a simple and gentle restraint option could be a lifesaver for cats that are difficult to manage.

"This is something owners can do throughout a cat's life during simple tasks like brushing their teeth or trimming their claws, and the cat won't be upset about it," he said. "There are 2 million to 3 million cats a year that get killed in this country because owners can't do things like trim their claws. And if the owner learned how to do this, and was trained properly in how you teach a cat to permit you to clip its claws, then these kinds of procedures could save millions of cats' lives per year."

Co-authors of the study were Megan Pozza, Judi Stella and Susan Wagner of Ohio State's Department of Veterinary Clinical Sciences, and Anne-Claire Chappuis-Gagnon of the Clinique Vétérinaire Réservée aux Chats in Sainte Foy Les Lyon, France.