Lopez, from Portland, Oregon, told police that he’d been drinking alcohol at the time of the alleged incident and committed the assault “out of anger.”
Estrella, a Lhasa Apso breed, initially “seemed fine” following the attack, court documents said.
The girlfriend later heard Estrella whining while hiding under the couch and discovered blood and injuries to the animal, Oregon Live reported.
She brought the dog to nearby animal DoveLewis Emergency Animal Hospital where vets took the decision to put the animal down.
According to reports, the partner of Lopez told nurses that her partner displayed some “potential bestiality tendencies.”
He once bragged about watching another person sexually assault a dog and would occasionally show his genitals to them, she claimed. He also suggested getting a dog larger than Estrella, she said.
A necropsy was performed on Estrella after she was euthanised and traces of Lopez’s DNA were found in the dog.
Lopez is currently being detained at Multnomah County Detention Center on suspicion of first-degree aggravated animal abuse and sexual assault of an animal.
His fiancée told authorities that she was be concerned about her family’s safety if Lopez was released from jail.