Abstract: The invention relates to a harness comprising a belly strap for surrounding the animal belly and a front strap for surrounding the front area of the neck, joined to one another by side connecting members, a lower connecting strap joining the belly strap with the front strap, and a symmetrical length-adjustment device comprising two upper straps connecting the side connecting members respectively to a first and a second portion of a releasable clip that can be located as desired along said upper straps.