Are animals property, or should they be considered protected sex partners?

In July 2017 on a farm near Bath, South Dakota, a farmer found James Schumacher, 56 in his barn having sex with a baby calf only four weeks old. When the sheriff's deputy arrived to investigate, Schumacher said he had a “legitimate reason” to be there, but he was still arrested and ultimately charged with six counts of bestiality. 

Schumacher's attorney now argues all charges should be dismissed because the law prohibiting bestiality is unconstitutional and violates his client's 14th Amendment rights. The argument goes like this: Schumacher has a constitutional right to decide whom (or what) he wants to have sex with, and any interference with that decision is a violation of his right to privacy. Further, animals are property, not people, and if he chooses to have sex with an animal, but there's a law against that, the law demeans people like him, therefore denying his right to equal protection under the law. 

It's an uphill climb to win the argument that Schumacher's constitutional rights have been denied. First, the calves did not belong to Schumacher, so whether they are considered property or not, Schumacher's property rights were not violated. Second, animals as sex partners are not considered a protected group. 

Florida resident Carolos Romero attempted this argument in 2012 after he was caught fondling his donkey while he masturbated. Ultimately, Romero took a plea deal and got a year in jail and a $200 fine. Robert Bonynge owned a strip club in Minnesota, and like to film his dancers having sex with his Rottweiler.  Bonynge was convicted on one count of bestiality for masturbating the dog, and four counts of aiding and abetting bestiality for filming the women having sex with the Rottweiler. Bonynge appealed his conviction arguing that the seizure and evidence submission of the videotapes violated his 1st, 4th, and 14th Amendment rights. The court found that his conduct was prohibited by Minnesota statutes and that the tapes constituted obscenity under Federal law. The lower court ruling was upheld.