A blazed rat is an otherwise normally colored or marked rat with a white stripe stretching from the nose to between the ears. The two most common types of blazes are "wedge" blazes, where the white covers the nose and whisker beds and stretches up to an even point between the ears, and "lightning" blazes, which run in a jagged line across the face. Many clubs restrict the types of markings that are allowed to include blazes, but they are not known to be associated with any particular color.

Blazes are believed to be the result of a modifier on the Hooded (H) locus, but are not genetically described. There are believed to be multiple genes controlling blazing. Some are the result of white-spotting genes and may lead to an increased chance for megacolon, therefore they should only be bred from known lines, and with care.

AFRMA

"Blazed rats may be shown only in berkshire or variegated classes in any recognized color. A wedge shaped blaze of white should run from muzzle to ears including the whisker beds, tapering to a fine point at the ears. Other markings as for respective pattern."

RSA

"Blazed shall come in two types: wedge and non-wedge. Blazed rats shall only be shown in berkshire, variegated or banded patterns. Wedge blazes shall begin at the nose tip to include the whisker beds and come to an even point in the center of the face, not extending beyond the ears. Blaze not to include cheeks or eyes. Non-wedge blazes must begin at the nose and must include, to some degree, the center of the face. Not to extend beyond the ears. Though non-wedge blazes can be of any shape and size, a symmetrical marking is to be preferred."

URS

"Blazed rats to be shown with Berkshire or Variegated varieties. To be a symmetrical wedge-shaped white marking starting as a fine point located midway between the eyes and the ears. White to encompass bridge of the nose, enveloping the nose, whisker-bed and mouth of the rat in a thin triangle.

Fault: Thin blazes"

Blue Berkshire with wedge blaze (c) Gabriel Edson