While cats are the most popular pet in the United States,1 their most common behavioral problem for which owners seek assistance, housesoiling, is unpopular with their owners. In
fact, housesoiling can lead to a cat's outdoor banishment, relinquishment, or euthanasia. Studies support this regrettable
outcome, with behavioral problems—primarily housesoiling—being a leading cause of cats' relinquishment to shelters.2 In one study, more than 23% of cats relinquished to a shelter had daily or weekly housesoiling incidents.3 A recent study found that the most common problem identified after the adoption of a cat from a shelter was housesoiling,
with 9% of the cats in the study exhibiting this behavior within three months of adoption.4 The study also identified housesoiling as a risk factor for returning the adopted cat to the shelter.4
There are three main causes of housesoiling in cats: underlying medical problems (e.g. feline lower urinary tract disease [FLUTD]), urine marking (communication), and toileting issues (e.g. litter box aversions, preferences for other sites or substrates). These diagnoses are not mutually exclusive; for example,
a cat with FLUTD may develop a litter box aversion. Evaluating a thorough history and the results of a physical examination
and diagnostic tests can direct the diagnosis and subsequent treatment.
In addition, toileting problems can stem from a variety of causes. Many toileting issues are secondary to issues with the
litter or litter box. But a toileting problem can also stem from factors that are unrelated to the litter or litter box, such
as intercat aggression. For example, a cat that is frightened of other cats in the home may feel vulnerable accessing or using
the litter box and may ultimately select an inappropriate toileting site. So again, it is always critical to get a comprehensive
history to correctly identify the motivation for the problematic behavior.
This article focuses on new research related to litter and litter boxes that may be helpful in preventing and treating toileting
problems. By getting the latest scoop on litter, you will be better prepared to prevent and resolve litter- and litter-box-related
toileting problems in your feline patients.
Litter preferences probably originated with the domestic cat's evolutionary predecessor, Felis silvestris lybica, the African wildcat.5 A desert-dwelling creature, the African wildcat used the desert sand as its toilet, establishing a substrate preference
that has apparently persisted throughout the domestication process.
With the transition of cats into our homes and the need to provide an adequate indoor toileting option, commercial litters
were developed. As different options appeared on the market, preference tests for various litter types were conducted on cats.
A study in the early 1990s identified cats' strong preference for finely granular sandlike material, widely known as clumping or scoopable litter, compared with large-granule litter, such as litter made of plain clay or recycled paper products.6 As new litters have entered the market, such as silica (crystal) litters, a preference for clumping litter has continued
to prevail in comparative studies.7
The litter market offers a wide variety of litters, including litters made of wheat, corn, paper, silica, and plain or clumping
clay. Within each of these litter categories are several brands or varieties with different additives. For example, the basic
component of clumping clay litter is sodium bentonite, clay made from volcanic ash. Multiple ingredients may be added to the
sodium bentonite base, including fragrances, fillers, bacterial growth inhibitors, and absorption additives, to create a unique
litter product. In general, the best litter products have a substrate that cats like the feel of, provide superior odor control,
and have minimal dust.