Cats have recently become the nation's most common pet. Cats have overtaken dogs in recent years because the former are more adapted to the indoor living conditions imposed by the increased proportion of apartment and condominium residences, which do not have the private yards that larger dogs require in which to roam. Furthermore, cats can be trained to eliminate their wastes indoors and do not require outdoor walking.
However, indoor pet elimination has its drawbacks. While the use of absorbant granular pet litter has achieved almost universal acceptance, the litter is itself messy and unsanitary to change and dispose. In addition, not all waste is absorbed or mixed with the litter. Instead, waste often adheres to the sides and bottom of the litter box, necessitating periodic cleaning of the box itself. Odor is often a problem in open topped litter boxes. Finally, the cat's natural inclination to scratch often causes litter and waste to be thrown out of the box.
Considerable effort has thus been directed toward construction of a pet litter box which addresses these and other problems.
Prior developments in this field will be generally illustrated by reference to the following patents:
______________________________________ U.S. Pat. No. Patentee Issue Date ______________________________________ 3,890,930 M. A. Clark 06/24/75 4,352,340 J. R. Strubelt 10/05/82 4,348,982 J. W. Selby 09/14/82 4,739,725 J. B. Fennelly 04/26/88 4,732,111 W. J. Runion 03/22/88 3,752,120 S. W. Pallesi 08/14/73 4,299,190 A. Rhodes 11/10/81 3,872,832 C. Quinn 03/25/75 4,667,622 D. S. Breault 03/26/87 4,711,198 G. R. Mossbarger 12/08/87 ______________________________________
U.S. Pat. No. 4,739,725 teaches the idea of multiple replacement units for animal litter boxes.
U.S. Pat. Nos. 4,732,111, 3,752,120, 4,299,190, and 4,352,340 teach replacement units for litter boxes in which liner units are disposable.
U.S. Pat. Nos. 4,348,982 and 3,890,930 teach peaked roof litter boxes wherein a single litter liner opens upwardly.
The rest of the patents are representative of what is in the art.