"The Crane Creek Wildlife Experiment Station of the Ohio Division of Wildlife conducted an analysis of skulls taken from encounters with wild canids in Ohio,cited in The Ohio Journal of Science. "From 1982 to 1988, skull collections were made in 71 counties, yielding 379 (87%) coyotes, 10 (2%) coydogs, and 25 (6%) feral dogs." The figures do not add to 100% because of skull damage hindering positive identification. "The incidence of coydog hybrids was high only in areas of expanding, widely dispersed coyote populations. [...] Mengel (1971) reviewed behavioral and physiological reasons why coydogs are adapted for survival less well than coyotes. These included inappropriate whelping time, lack of parental care by the male, and decreased fertility."
I believe I also said they were extremely rare--see the above quote--and follow this link
http://en.wikipedia.org/wiki/Coydog . It is not an impossible hybrid that can be encouraged by a breeder--although I don't know why they would. The point that coydogs are any worse than pure coyotes is the
myth--assuming they were raised by a coyote parent they won't be any worse or better as far as fear of humans. The worst offenders would be feral dogs, especially those who grew up with humans, as well as pure coyotes that have lost their fear of humans. Saying coydogs are to be feared because of the cross is not true--thereby lies the myth. Also, which is pointed out in the link, one of the reasons behind the coydog idea is that it arose, in the east at least, because of the larger size of the Eastern Coyote--many thought (and still do) that this was because they interbred with dogs. This is not the case, they interbred with wolves giving them a whole new genetic and behavioral criteria--making them bigger and pack animals.