Cat litter

Cat litter is one of any of a number of materials used in litter boxes to absorb moisture from cat feces and urine, which reduces foul odors such as ammonia and renders them more tolerable within human dwellings.

Several kinds of cat litter are commercially available, enabling consumers to decide which factors are most important. Some cat owners are concerned about litter being tracked throughout the house, while others may look for litters that are biodegradable. Absorbency and odor control are other considerations.

Conventional litter
One of the first commercially available cat litters was Kitty Litter, invented in 1948 and marketed by Ed Lowe. This was the first use of clay as an absorbent; prior to this time sand had been used in litter boxes instead. The new clay litter was more absorbent than sand, and its larger grain made it less likely to be tracked from the litter box. The brand name has become a genericized trademark, used by many to denote any type of cat litter.

Conventional clay litter is indistinguishable from clay-based oil absorbent (used to clean oil spills); as the latter is far cheaper, it is often used as a substitute.

Clumping litter
Clumping litters were first developed in the UK in the 1950s by the Fuller's Earth Union, later to become a part of Laporte Industries Ltd. The type of clumping litter developed by the FEU was calcium bentonite, a less swelling and less sticky type than American bentonite. Subsequently in America, clumping bentonite was developed in 1984 by biochemist Thomas Nelson. Most are made from granulated bentonite clay which clumps together when wet and form a solid mass separate from the other litter in the box. This solid clumped material can then be disposed of without changing the entire contents of the litter box often. However the entire contents should be changed on a regular basis to prevent buildup of bacteria, every four to six weeks is recommended. At the same time, the litter box itself should be disinfected. Approximately 60% of the cat litter market consists of clumping litter. Clumping litter also usually contains quartz or diatomaceous earth (sometimes called diatomaceous silica, which causes it to be mistakenly confused with silica gel litter).

Some claim that clumping litters can be harmful to pets because if it is ingested or inhaled, it swells and solidifies inside them. This is thought to be particularly dangerous for kittens, who are more likely to ingest cat litter and less likely to recover easily. For the same reason, it is not recommended to flush clumping litters down the toilet.

Silica gel litter
Silica gel litter, a porous granular form of sodium silicate, has the highest absorbency of any litter, and has excellent moisture and odor control. Cat lovers' opinions about crystal cat litter are divided.

Some praise its absorbency because 4-5 lbs can absorb liquid and odor for up to 30 days for one healthy normal weight cat. Stir it daily when 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. In comparison, over the same time period it may take 20-30 lbs or more of clay or clumping litter because you have to replenish the clumped urine that is scooped out.

Others dislike that crystal litter gives them no warning when it is saturated. So the next cat to use the litter box will leave a urine puddle at the bottom of the pan. Crystal litter is extremely lightweight, especially when compared to heavier clay and clumping litter.

Silica gel litter comes in two shapes: irregular lumps and small beads. Sizes range from 0.5 mm to 4 mm.

Biodegradable litter
Biodegradable litter materials are pellets made of recycled paper, wood shavings (primarily pine), wood, corn cobs, dried orange peel, or wheat bran. Some pet owners prefer these litters due to their perceived friendliness to the environment; others are attracted by the flushability of the litter. Asthmatic cats may sometimes benefit from the reduced dust in some forms of biodegradable litter. They tend to be more expensive than traditional clay litters, so cost is not a positive factor in their selection, however some biodegradeable litters such as the sawdust pellet type last much longer than clay litter, one inch of sawdust litter can last over two weeks per cat. Also, most of these forms of litter are recycled from human usage and are thus re-using a waste product as opposed to drawing clay from litter mines.

Litter for dogs
Although most dog-owners housebreak their pets, enough people train their dogs to use litter boxes that the one company manufactures a product sold as a special dog litter.