function playPerro(){

    document.getElementById("audiocerdo").pause();
    document.getElementById("audiovaca").pause();
    document.getElementById("audiogato").pause();

    document.getElementById("audioperro").play();
    document.getElementById("perro").className="animal pequenio";

    var claseAnimacion = document.getElementsByClassName("animal pequenio");

    function myPause() {
        document.getElementById("audioperro").pause();
        claseAnimacion.classList.remove("pequenio");
    }
    setInterval(myPause, 5000);

}