A bit of Apple history. From wikipedia:
The dogcow, also known as Clarus the Dogcow, is a bitmapped image first introduced by Apple. It is the shape of a dog, originally created in 1983 as part of the Cairo font by Susan Kare as the glyph for “z.”
That image was later chosen for the Mac OS Print Setup dialog box, though it needed to be slightly redrawn because the original Cairo dog did not proportionally fit the Print Setup dialog box. This modified version became the image famously known as the dogcow.
The term “dogcow” was first coined by either Scott Zimmerman or Ginger Jernigan. Mark “The Red” Harlan named the dogcow “Clarus” as a joking reference to Apple’s former office-software unit, Claris. The sound she makes is Moof!