Along with a set of beguiling, intimate color photos of puppies and parent dogs, lambs and adult sheep lying down together, touching noses and comfortably mingling on a wintry prairie, Wyoming rancher/journalist Urbigkit describes in terse captions how guard dogs are “socialized” with their ovine charges from birth. That is, she writes, virtually the only training they receive or need to develop a sense of mutual dependency. Closing with a list of common breeds of American guard dogs and a bit of historical background, this will not only replace George Ancona’s out-of-print Sheep Dog (1985) in libraries, it will rivet young dog lovers in general. And it makes a great lead in to the likes of James Herriot’s Only One Woof (1985), illus by Peter Barrett or, for older readers, Jon Katz’s Dogs of Bedlam Farm (2004). (Picture book/nonfiction. 5-9)