This is not the type of news that Arizona's Politics covers, but it did prompt several questions. MCSO Dep. Joaquin Enriquez, a Media Relations Spokesman, provided some valuable context.
More than one of the MCSO arrests have been of out-of-staters who have responded to the MCSO's internet bait. Other Google news accounts of bestiality arrests from this year appear to deal with in-state activities.
Enriquez states that the "MCSO appears to be the only law enforcement agency in the country that has a dedicated animal crimes unit. Within that unit, one detective is tasked with focusing on bestiality cases, and has been for the past two years." Some law enforcement agencies around the nation do appear to have units or task forces which handle animal-related crimes, but we found no evidence of any focusing on bestiality, let alone conducting an ongoing internet sting.
The Deputy also notes that "There is no reason to believe that bestiality has risen in frequency, nor is it a new phenomenon. What is new is the attention MCSO is paying to it."
Our 2nd question had to do with the statuses of the 8 previous requests. Enriquez replied that they have all been convicted.
Finally, Arizona's Politics wondered how much the MCSO prioritizes this crime. In addition to the comment above that one detective focuses on bestiality cases, Enriquez says "In truth, if we had more deputies involved, we'd have more cases, and we could probably keep a surprising number of deputies busy. However, it is a case of priorities and resources, and so we are devoting as much as we can to this crime without shortchanging other needs."
Arizona's Politics has asked some follow-up questions, and will update as necessary.