Small animal restraining harness or jacket

An animal restraining harness or jacket and a method of use thereof, for protecting the shoulder and upper abdomen when experimental/surgical procedures are performed and when the experimental/surgical sites must be protected from biting, scratching, and other unwanted contact. The jacket generally includes a shoulder region and collar extensions, where the shoulder region is connected to the collar extensions. The collar extensions are wrapped and secured around the collar or neck area of the animal, and the shoulder region is wrapped and secured around the shoulder and torso area of the animal. Preferably, the collar extensions and shoulder region are secured on the dorsal side of the animal, thus providing a dorsal gap therebetween. This harnesses the animal effectively and prevents escape from the restraining jacket.