Const. Adam Rayner says Tessa, a female miniature Australian Shepherd, vanished from her home in Lamont County on Wednesday.
Rayner says Tessa was expecting a litter of puppies in the next six days.
He says the dog's owners had advertised the expected puppies online, saying they would cost about $750 each.
Rayner says the value of the litter could exceed $5,000, making that a possible motive for the theft of the dog.
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