Oliendo a Perro(2011)

Tavo, a self-proclaimed fashion photographer from Monterrey is secretly following his sexbomb model girlfriend hoping to catch her in a suspected infidelity. Hacking into her computer with the help of his best friend Horacio, they soon find more than expected, falling into a downward spiral of strange encounters and bizarre outcomes. As the hours go by and the evidence piles up, they become convinced she's having an affair with a dog.