var Pfoten1 = new Image();
    Pfoten1.src = "images/pfoten1.gif";
    var Pfoten2 = new Image();
    Pfoten2.src = "images/pfoten2.gif";
    var Pfoten3 = new Image();
    Pfoten3.src = "images/pfoten3.gif";
    var Pfoten4 = new Image();
    Pfoten4.src = "images/pfoten4.gif";

    var zaehler = 0;

    function bildwechsel() {
      if (zaehler == 0) {
        document.getElementById("inhalt").style.backgroundImage = "url(images/pfoten2.gif)";
        zaehler++;
      } else if (zaehler == 1) {
        document.getElementById("inhalt").style.backgroundImage = "url(images/pfoten3.gif)";
        zaehler++;
      } else if (zaehler == 2) {
        document.getElementById("inhalt").style.backgroundImage = "url(images/pfoten4.gif)";
        zaehler++;
      } else {
        document.getElementById("inhalt").style.backgroundImage = "url(images/pfoten1.gif)";
        zaehler = 0;
      }
    }

    setInterval("bildwechsel()", 3000);