Litter box

The first commercially available cat litter in the United States was Kitty Litter, available in 1947 and marketed by Ed Lowe. This was the first large-scale use of clay (in the form of Fuller's earth) in litter boxes; previously sand was used. Clay litter is much more absorbent than sand and is manufactured into large grains or clumps of clay, making it less likely to be tracked from the litter box. The brand name Kitty Litter has become a genericized trademark, used by many to denote any type of cat litter. Today, cat litter can be obtained at a variety of retail stores for quite an economic price. Non-clumping cat litter is often made of zeolite, diatomite and sepiolite.[6]

Microscopic close-up of clumping cat litter, showing the fossilized remains of diatoms

Litter clumps were first developed by using calcium bentonite clay. This was manufactured in the UK in the 1950s by the Fuller's Earth Union (FEU), which later became a part of Laporte Industries Ltd. Subsequently in America, clumping bentonite was developed in 1984 by biochemist Thomas Nelson.[7] Most are made from granulated bentonite clay, which clumps together when wet and forms a solid mass separate from the other litter in the box. This solid clumped material can be scooped out and disposed of without changing the entire contents of the litter box.

Clumping litter usually also contains quartz or diatomaceous earth (sometimes called diatomaceous silica, which causes it to be mistakenly confused with silica gel litter). Because of the clumping effect, the manufacturers usually instruct not to flush clumping litters down the toilet, because it could clog it.[8]

Clumping clay cat litters are natural products. Some may also contain naturally occurring crystalline silica, or silica dust, which in California is treated as a known carcinogen under Proposition 65.[9] Clay litters is also criticized by the manufacturers of non-clay litter because the components of clay litter are commonly obtained from a strip mine in an environmentally degrading process.[10]

This sort of litter can be toxic to ferrets, leading to both respiratory and digestive problems.[11]

Biodegradable litters are made from various plant resources, including pine wood pellets, recycled newspaper, clumping sawdust, Brazilian cassava, corn, wheat, walnuts, barley, soy pulp[12] and dried orange peel.

Each year, more than two million tons of cat litter, or approximately 100,000 truckloads, ends up in landfills in the U.S. alone. Primarily this is not biodegradable or renewable and adds to the waste burden.[13] Some pet owners prefer biodegradable litters due to its friendliness to the environment. Biodegradable cat litter can also be eliminated completely by safely composting the used litter at home. Other cat owners can be attracted to the biodegradable litters because of their flushability or deodorizing properties.[14] Some pets, such as those with asthma or sensitive senses of smell, may also benefit from the reduced dust in some forms of biodegradable litter.

Biodegradable litter packaged specifically for cats tends to be more expensive than traditional clay litters, so cost is often not a positive factor in their selection. However, one of these, namely pine pellets can be purchased from regional feed stores that normally carry 40 lb (18 kg) bags for horse bedding at a significant cost reduction, often cheaper than the cheapest clumping litter. Most biodegradable litters last longer than the equivalent size of clay or clumping clay litters. Grain-based animal or poultry feed also provides an economical alternative to products marketed specifically as cat litter Also, most of these forms of litter are recycled from human usage and are thus reusing a waste product as opposed to drawing clay from mines.

Silica "crystal" litter

Silica gel litter, often referred to as "crystal litter", is a porous granular form of silicon dioxide, has the highest absorbency of any litter, and has excellent moisture control and complete odor elimination for an extended period of time compared to other litters.

Some owners praise its absorbency because 4–5 pounds (1.8–2.3 kg) can absorb liquid and odor for up to 30 days for one healthy normal weight cat. It is important to lightly stir the crystals daily while scooping the solid waste, otherwise urine can pool in the box. When crystal litter is saturated, at the end of 30 days or so, it begins to smell and is visibly saturated (the white crystals have turned slightly yellow). In comparison, over the same time period it may take 20–30 lb (9.1–13.6 kg)[15] or more of clay or clumping litter, because it is necessary to replenish the litter that is removed when the clumped urine is scooped out. No replenishing is necessary with silica gel (crystal) litter.

PrettyLitter is a proprietary silica gel litter with health diagnostic features. Its litter changes color as a reaction to a cat's urine to indicate potential health issues. The litter turns blue in the presence of high alkaline urine (a potential an indication of a urinary tract infection), yellow for high acidic urine (potentially indicating metabolic acidosis or kidney tubular acidosis), or red in the presence of blood in the urine (which might indicate bladder inflammation, bladder stones, or a urinary tract infection).[16]

An open litter pan is generally the most basic and least expensive design. They are commonly constructed out of plastic, however some disposable models exist, in the shape of a rectangular tray with outwardly sloped sides 3.9 to 5.9 inches (10 to 15 centimeters) high. Open litter pans allow for maximum ventilation which may increase cat comfort. However, they do show the waste most visibly and trap no odors which may encourage owners to scoop the box more frequently. Litter pans with low walls are not ideal for containing litter when a pet scratches or digs. Also, some animals who eliminate standing up may be able to urinate or defecate over the walls. Some designs include a detachable rim to help catch litter when the animal kicks to bury their waste.

An enclosed litter box

A variety of covered litter boxes exist that are commonly available and moderately priced. Many are constructed out of plastic and feature a plastic hood or dome that covers the litter pan and litter. The pet enters through an opening in the cover, these may be open or have a swinging door. To clean, pet owners lift the cover off the tray to scoop and change the litter. Covered litter boxes may help reduce the amount of litter that is tracked outside the box, may help address issues of pets eliminating waste over the walls of a litter pan, and may help reduce odor.

Top entry litter boxes have an opening on the top of the box and require the pet to climb on top of the box and into a hole to eliminate waste. While cats in good physical health, even kittens, have no problems accessing these boxes, they are generally not recommended for geriatric or physically limited felines.[17] However, top-entry designs do have the added benefit of deterring other pets or young children from the contents of the litter box. Some designs feature a grate on top which allows litter from a cat's paws to fall back into the box, reducing litter tracking.

A cat using an automated fully-plumbed self cleaning litterbox with reusable plastic granules, which has a cleaning cycle that includes: automated scooping, waste flushing to laundry drain, cold water granule wash, deodorization, followed by a heated drying of the litter granules.

Self-cleaning litter boxes employ technology that automates the litter box emptying procedure. Some models have electric combing mechanisms that automatically scoop the clumps out of the litter box into a sealed, disposable-bag-lined container after the animal has used it. These models use a pressure pad or an infrared light to determine when the cat has left the box and will comb the box after a pre-determined amount of time has passed to avoid disturbing the cat. Other designs take this one step further by connecting directly to a home's plumbing (faucet connection and drain) so they can wash, rinse and dry the permanent litter pellets automatically. Simpler designs exist as well; for example, some require the owner to manually shake the clumps into an easy-to-remove tray. Another variant has an enclosed sphere which rotates as it sifts out the clumps and deposits them in a drawer below the sphere. A new method involves incorporating sifting functionality within a sifting litter liner.[18] Some automated litter boxes incorporate the use of a two-belt system. The top belt has litter ready to use while the lower belt has a batch of litter ready "on hold" for when the cleaning process takes place. As the litter on the bottom belt is moved up to the top, is it evenly distributed across the width of the top belt.[19]

This newer design has increased in popularity with cat owners for their convenience, odor control and travel ability. These litter boxes are disposable and as such do not require going through any of the pain of cleanings or litter refills. Some disposable litter boxes may come with an included bag of litter or owners can choose to fill them with their own. They are also marketed for use inside of pet crates or carriers to eliminate accidents, and may also help control odors if they are thrown away and changed routinely. Once the product has been used to completion, owners can simply dispose of both the litter box and its contents.[20]