Excellent article from Fortean Times by Jon Downes:

Texas Blue Dogs: Jon Downes travels to the Lone
Star State to solve a canine cryptozoological mystery

My search for the blue dogs of Texas began in November 2004, when I visited a farm in Elmendorf, just south of San Antonio, where local rancher Devin McAnally had shot a hairless, blue-skinned canid in July that year. He took photographs of it to a local convenience store where one of the customers said that it looked just like “the chupacabra that her grandmother had told her about when she was a girl”.

Thus was born the legend of the Texas chupacabra. I took one look at the bones of the unfortunate creature and was convinced that it was nothing of the sort.
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But what were they?
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Once again, the description was of blue/grey, hairless, dog-like creatures larger than the largest coyote, with long muzzles and hunched backs.
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From the available evidence, they show – at the very least – that wolves are not entirely extinct in Texas, and we hypothesise that the discovery of these wolves may have enormous implications for the survival of the rarest sub-species. The Elmendorf creature is something else entirely. Whether or not it is a surviving member of the pre-Columbian domestic races of dog we may never know.
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lengthy article quite worth the reading for those interested in cryptozoology at link above