Nonlethal tools for reducing livestock depredations, such as livestock guardian dogs (LGDs; Canis familiaris), reduce lethal management of livestock predators and have been widely adopted by domestic sheep (Ovis aries) producers in the United States. However, compared with their success in reducing coyote (Canis latrans) depredations, commonly used LGD breeds appear less effective against wolves (Canis lupus). With more than 30 distinct LGD breeds found throughout the world, certain breeds may be more effective at deterring specific threats. We compared LGD breeds commonly used in the United States, collectively called whitedogs, with three European breeds selected for boldness toward carnivores, history of use in areas with wolves, lack of aggression toward humans, and size. We collected data on LGD behavior with sheep herds in Idaho, Montana, Oregon, Washington, and Wyoming in 2015 and 2016. We also developed a test to examine LGDs' response to a simulated encounter with a wolf while on summer grazing range. Results from generalized linear mixed models of proportion of time spent in a given behavior indicate that few significant behavioral differences exist among tested breeds. Kangals tended to be more investigative when engaging a decoy, karakachans more vigilant, and transmontanos more able to decipher a threatening from unthreatening stimulus. Transmontanos also spent less time scanning than whitedogs, and there was a marginally significant effect of karakachans moving more than whitedogs. While these subtle behavioral differences may help livestock producers make tailored decisions in choosing the appropriate LGD for their needs and circumstance, our results suggest that behavioral differences among breeds may be less common than often suggested.