Odor inhibiting pet litter

The addition of urease negative bacteria to sodium smectite clay minerals in pet litter inhibits growth of urease positive bacteria for a period of several days, thereby retarding formation of ammonia and other obnoxious odors. Approximately fifty percent sodium bentonite in the litter causes the litter to clump upon wetting, maintaining the urea in contact with the treated clay and also serving as a buffer to favor growth of the urease negative bacteria.

TECHNICAL FIELD 
The invention generally relates to animal husbandry, especially to material 
for absorbing moisture from waste products. The invention discloses a clay 
based pet litter in which a bacterial element is mixed with certain types 
of clay to inhibit formation of ammonia from urea for a period of several 
days. 
BACKGROUND ART 
Household pets often are kept indoors and deposit their wastes in an 
absorbent composition, referred to as pet litter or cat litter. Half a 
century ago, indoor pets commonly used a box of sand to receive their 
wastes. Since then, pet litter has evolved into a specialty market, which 
began with the use of industrial absorbents. Today, a suitable base 
material for producing pet fitter is clay, which is inexpensive, absorbs 
liquids, and is easily disposed of, such as in the garden, or in the 
trash. Many clays are used as pet litters because of their excellent 
absorptive qualities. Among them, attapulgite clay, which is hydrous 
magnesium aluminum silicate, is one of the most commonly used pet litters. 
Similarly, fuller's earth is a combination of attapulgite clay and 
bentonite clay. 
Bentonite, which is a montmorillonite clay, is formed of hydrous magnesium 
aluminum silicate and is widely used as pet litter. Its two common forms, 
sodium bentonite and calcium bentonite, are distinguished by having either 
sodium or calcium cations. Calcium bentonite, also known as southern 
bentonite, is an acid activatable clay that can be treated with 
hydrochloric acid or sulfuric acid to significantly increase its surface 
area and enhance it absorptive properties. It is the better absorbent of 
the two. Sodium bentonite has the ability to swell several times and forms 
gel-like masses in water, while calcium bentonite swells much less. Sodium 
bentonite also is known as Wyoming or western bentonite. 
Two other common pet litters are kaolin, or china clay, and sedimentary 
opal clay mixtures. Kaolin is a hydrous aluminum silicate of the Kaolinite 
mineral group, having the formula Al.sub.2 O.sub.3.2SiO.sub.2.2H.sub.2 O. 
A commercial opal clay mixture contains sedimentary opal. Opal clay 
contains about 20 percent more silicon dioxide than is found in bentonite 
and has high porosity, which provides a high absorption capacity. Both 
clays are commonly sold as pet litter. 
The process of producing a clay based pet fitter is similar with any type 
of clay material. Raw clay, which typically contains about 35 percent 
water, is mined from an open pit. Large earth movers deliver the clay to 
trucks, which haul it to a plant where it is dried in a kiln and crushed 
in several stages. During processing, different clays and other 
ingredients can be blended to produce a pet litter having special 
qualities, such as clumpability or odor control. After blending, the 
product granules are sorted by screening into various sizes. The final pet 
litter can be a mixture of sizes, which is more absorbent than when all 
granules are the same size. 
The usefulness and performance of ordinary clay or other litter materials 
has been improved in three general areas. First, it has been discovered 
that litter is easier to keep clean if wet particles agglomerate or clump 
together, making it easier to remove the spent litter and waste products 
from the unspent litter. Second, several experimenters have added chemical 
or biological agents to litter in an attempt to digest the animal wastes 
or otherwise reduce odors. Along these same lines, litter can be scented 
to mask odor. Third, special litter materials have been developed that are 
especially absorbent. Several patents have issued in each of these areas. 
The first type of patents disclose several techniques for clumping litter 
particles when wetted. For example, U.S. Pat. No. 5,216,980 to Kiebke 
combines granular clay with a gluten containing hydrophilic media. U.S. 
Pat. No. 5,183,010 to Raymond et al uses potato starch, gum, or polyvinyl 
alcohol to bind wet particles, plus boron to accelerate hardening. U.S. 
Pat. No. 5,152,250 to Loeb mixes granular litter with grain flour to cause 
agglomeration and mineral oil to cause the flour to adhere to the grains. 
U.S. Pat. No. 5,094,189 to Aylen et al adds potato starch to bentonite 
clay. U.S. Pat. No. 5,000,115 to Hughes mentions that certain natural 
bentonite clays, alone, are capable of clumping when wetted. U.S. Pat. No. 
4,685,420 to Smart uses a polymer in clay to form a gelled agglomerate 
when wetted. 
These and other methods of causing spent litter to clump offer an 
improvement over non-clumping litter. Because only wet litter forms 
clumps, the spent litter and the waste contained by it can be completely 
removed from the litter box, while permitting unused litter to remain 
behind. Thus, clumping litter is efficient and economical, allowing both 
solid and liquid waste to be removed from the litter box without requiring 
that the balance of clean litter also be removed. Further, clumps are easy 
to remove from a litter box, which makes the cleaning job much more 
pleasant and raises the expectation that this job will be done more 
frequently. Consequently, it is expected that clumping litter results in 
decreased waste odor in the home, due to the frequent and complete 
cleanings. 
The second type of patents add a chemical agent that is intended to reduce 
odor. For example, U.S. Pat. No. 5,303,676 to Lawson combines bentonite 
with sodium bicarbonate or potassium bicarbonate coated with a mixture of 
mineral oil and siliceous material to deodorize the litter. ZnO can be 
added as a bactericide. U.S. Pat. No. 4,607,594 to Thacker combines 
bentonite with perlite, which has been treated with carbonate, bicarbonate 
or hydrogen phosphate. U.S. Pat. No. 4,517,919 to Benjamin et al adds 
undecylenic acid, a fungicide, to bentonite or other base material. U.S. 
Pat. No. 4,494,481 to Rodriguez et al uses transition metal salts in the 
litter box to control urine odor. U.S. Pat. No. 4,459,368 to Jaffee et al 
mixes calcium bentonite with calcium sulfate dihydrate to control odor. 
U.S. Pat. No. 4,437,429 to Goldstein et al uses zeolites to control odor 
in bentonite. U.S. Pat. No. 3,941,090 to Fry adds cedar bound with 
alfalfa. U.S. Pat. No. 3,916,83 1 to Fisher uses popcorn as litter, with 
added bactericides. U.S. Pat. No. 3,892,846 to Wortham uses A1, Zn, Sn, Ca 
or Mg salt of an hydroxamic acid in litter to resist odor by inhibiting 
bacterial decomposition of urea to ammonia when wetted by urine. U.S. Pat. 
No. 3,789,797 to Brewer et al combines bentonite and alfalfa, which 
supplies chlorophyll. U.S. Pat. No. 3,636,927 to Baum adds camphane 
compounds, which smell like cedar oil. U.S. Pat. No. 4,844,010 to Ducharme 
et al uses cyclodextrin in clay to absorb nitrogenous compounds. U.S. Pat. 
No. 4,704,989 to Rosenreid adds absorptive materials to clay litter, 
deodorizers and bactericides. U.S. Pat. No. 4,67 1,208 to Smith adds 
limestone to litter to neutralize urine and raise pH. U.S. Pat. No. 
4,465,019 to Johnson adds dried citrus pulp to fitter. Japan Patent 
3044-822 discloses an animal litter composed of clay and a water insoluble 
chemical deodorant, which may be an organic acid and its salt. Japan 
3020-100 discloses use of bentonite, zeolite, or cristobalite plus 
deodorizer. EPO Publication 76,447 reduces ammonia content of air in 
animal stalls by lowering pH, through addition of a mixture of urea 
phosphate, phosphoric acid, sulfuric acid or alkali metal hydrogen 
sulphate and an organic acid. The low pH suppresses pathogenic bacteria by 
encouraging growth of acidophilic organisms such as lactobacilli, 
increasing lactic acid content. EPO Publication 39,522 manufactures litter 
from cellulosic fibers, pelletized, with added fungicides and 
bactericides. 
These chemical agents may achieve success, although it appears that some 
could be expensive and others might require large concentrations to 
effectively treat any significant volume of animal wastes. Some of the 
chemicals might cause environmental problems, especially if allowed to 
build up by disposal in a dump site or garden over a long period of time. 
For this reason, alone, the use of deodorizers, bactericides, fungicides, 
acids, metal salts, and perhaps other similar materials appears to be a 
poor choice. In addition, pets walk through the litter box. Thus, these 
chemicals will be in contact with the pet's feet for substantial periods 
of time, which might cause irritation or other health problems. As pets 
groom themselves, the chemicals may in ingested. Further, the pet may 
track these chemicals through all areas of the house, spreading potential 
problems to human inhabitants, as well. 
A few patents have attempted to use biologic agents to reduce odors. For 
example, U.S. Pat. No. 5,154,594 to Gamlen combines clay with digestive 
bacteria to break down the waste. Japan Patent 2154-629 combines multiple 
types of bacteria on a sawdust growth medium to break down ammonia, which 
is a bacterial decomposition product and major odor component, and other 
excrement and thereby prevent odor. Japan Patent 1085-125 discloses the 
combination of sawdust and thermophilic bacteria on the floor of a cattle 
shed to control odor. The mixture is placed in a compost shed for several 
weeks to produce mature compost. Soviet Union 1,091,889 discloses an 
animal bedding made of composted manure. Thermophilic bacteria in the 
manure cause an increased temperature that kills disease microorganisms. 
After composting, the manure is reused as bedding. Denmark Patent 86,908 
combines cellulose and coccidium-retarding agent plus a protein rich 
material. These biologic agent patents seem unlikely to be completely 
successful, since composting or digesting wastes produces odors. 
The third type of patent, in which absorbency is increased, is represented 
by United States Patent No. 4,557,881 to Crampton, which makes highly 
absorptive cat litter from clay fines that are compacted and then broken 
into larger particles. Absorbency is increased by adding an antideposition 
agent, which might include Wyoming bentonite, which is known to form a gel 
when wetted. The content of United States Patent No. 4,591,581 to Crampton 
is similar. Improving absorbency would be expected to make a litter more 
efficient, since liquid wastes might be captured in the granular material 
rather than being allowed to pool at the bottom of the litter box. 
These many approaches to improved handling of animal wastes demonstrate 
that controlling odor of animal wastes is long standing problem. Some of 
the approaches deal with specialized problems that are unlikely to be 
reproduced with home litter boxes. For example, those treatments directed 
to cattle barns are dealing with cellulose based wastes, since cattle are 
herbivores. In contrast, home pets like dogs and cats consume a modify 
protein diet and their wastes tend to be far more putrid. Those techniques 
that claim to digest wastes are unlikely to be a full household cure, 
since the digestion process itself produces ammonia, which is a source of 
strong obnoxious odor from wastes. Thus, it appears a household litter 
that is odor free or at least can delay significant odor formation for a 
substantial time period is yet to be developed. 
It would be desirable to have a litter or a treatment for litter that 
prevents formation of odor causing substances. Digestive schemes alone are 
unlikely to prevent odor, since digestion produces odor if only for a 
short time. 
Further, it would be desirable to have a litter that can prevent formation 
of obnoxious odor without requiring an added fragrance to mask various 
odors that ordinarily develop. The addition of a fragrance to litter, for 
the purpose of covering bad odors, often is not a satisfactory solution 
since the odor continues to exist in the background of the fragrance. Of 
course, animal wastes have an immediate odor that a mild fragrance might 
cover. It is subsequently developed odors, such as ammonia, that tend to 
be most obnoxious and permeating. These are the odors that are most 
important to prevent. 
Similarly, it would be desirable to have a litter or a treatment for litter 
that prevents formation of odors for at least a full day and preferably 
longer. Even the most attentive pet owner can be delayed from promptly 
emptying a used litter box. Ordinarily, the odors from a used fitter box 
become obnoxious quite soon after the use and soon can permeate a house. 
Therefore, if these odors are substantially eliminated for one or two 
days, or more, the ambience of the house is greatly improved. 
Moreover, it would be desirable to combine an odor free litter or treatment 
for litter with a clumping litter, both to simplify emptying the spent 
portion of litter from the litter box and to maintain the waste in contact 
with the treated litter for effective odor prevention. 
Another desirable goal is to control or suppress odor while using only a 
small amount of active agent. The chemical or biological treatments known 
in the prior art might involve prohibitive expense. Further, it would be 
undesirable to add significant quantities of any sort of agent to 
established litters such that they might change the character of the 
litter material, resulting in the agent being tracked about the house on 
the pet's feet. 
To achieve the foregoing and other objects and in accordance with the 
purpose of the present invention, as embodied and broadly described 
herein, the product and method of this invention may comprise the 
following. 
DISCLOSURE OF INVENTION 
Against the described background, it is therefore a general object of the 
invention to provide an improved odor inhibiting animal absorbent or 
treatment of animal absorbents suited for use in home litter boxes, in 
which animal wastes are prevented from producing obnoxious odors. 
A more specific object is to provide an animal absorbent that can delay 
odor formation for at least one day and preferably longer, after the waste 
contacts the absorbent. 
Another object is to provide an odor inhibiting animal absorbent that can 
work in combination with a clumping litter, so that the absorbent and the 
animal wastes are maintained in operative contact. 
A further object is to create a deodorized animal absorbent that is safe 
for use in a litter box, with respect to both the pet and humans in the 
house. 
Still another object is to provide a deodorizing treatment for pet litter 
that requires very little additive or treating agent. A low concentration 
of additive or treating agent is desirable to make the treatment 
affordable and prevent the pet from tracking the additive or agent. 
Additional objects, advantages and novel features of the invention shall be 
set forth in part in the description that follows, and in part will become 
apparent to those skilled in the art upon examination of the following or 
may be learned by the practice of the invention. The object and the 
advantages of the invention may be realized and attained by means of the 
instrumentalities and in combinations particularly pointed out in the 
appended claims. 
According to the invention, an odor retarding pet litter is formed of an 
absorbent composition and a urease negative bacterial culture combined 
with the absorbent composition, in an effective amount to inhibit growth 
of urease positive bacteria when, in use, the absorbent composition is 
wetted with animal waste containing urea. 
According to another aspect of the invention a method of suppressing 
production of odor in pet fitter is achieved by applying to a pet litter 
an effective amount of a urease negative bacteria.

BEST MODE FOR CARRYING OUT THE INVENTION 
The invention is an odor inhibiting pet litter, a method of treating pet 
litter materials to achieve odor inhibition, and a litter box containing 
the treated pet litter material. The products and methods of this 
application are based upon use of a urease negative organism that delays 
decomposition of solid and liquid animal wastes, with the result that 
ammonia is not formed and released with the typical frequency of such 
wastes decomposing in nature. Ammonia is believed to be the chief cause of 
obnoxious odors from liquid animal wastes aging in a litter box. During 
the period of prevention or delay, the urease negative organism 
effectively prevents formation of obnoxious odor. Organisms of this type 
are effective in low concentrations against the volumes of waste typically 
deposited in a litter box. In addition, such organisms are not harmful to 
animals or humans. 
In another aspect, the invention is an interactive system of urease 
negative organisms and buffer means. When the system is subjected to 
wastes, such as acidic urine, it maintains pH in a range favoring the 
organism. The buffer means may be the pet litter material, itself, 
especially when the litter material is a smectite (swelling) clay, such as 
sodium bentonite. The preferred pH range is basic, especially around pH 
7-9. 
A further aspect of the invention is the interaction of the organism with 
clumping pet litter materials. Numerous clumping pet litters are known in 
the art, including some that occur naturally and others that are man-made. 
A preferred clumping litter is formed of a substantial concentration of 
sodium bentonite, which is naturally occurring and inherently gels or 
clumps when wet. When used with other clays or pet litter materials, the 
concentration of sodium bentonite must be at least about fifty percent to 
realize the natural clumping action. Because sodium bentonite is a natural 
clumping material and also is a suitable buffer, this single material is a 
preferred choice. Further considerations are that sodium bentonite is 
plentiful, inexpensive, and already has been used as pet litter for many 
decades. It can be safely disposed of in compost, in the garden, or in the 
trash. 
Smectite clays are a group of minerals composed of units made up of two 
silica tetrahedral sheets with a central alumina octahedral sheet. 
Exchangeable cations are found between the silicate layers. The layers are 
stacked with oxygen atoms from each layer being disposed in a common 
intermediate layer. The bonding between adjacent oxygen atoms in the 
central layer is weak and results in cleavage between the units. Polar 
molecules such as water can enter between units and expand the lattice 
structure. Thus, the smectite clays are swell easily in the presence of 
water or other polar molecules. Some examples of smectites are the 
dioctahedral smectites: montmorillonite, beidellite, and nontronite; and 
the trioctahedral smectites: hectorite and saponite. 
A number of urease negative organisms are known and are suitable for use in 
a litter product. Among them are strains selected from group N 
streptococcus, such as lactococcus lactis ssp. lactis, lactococcus lactis 
ssp. cremoris, and lactococcus lactis ssp. lactis bio var diacetylactis; 
group D streptococcus, such as streptococcus faecium; pediococcus such as 
pediococcus acidilactici, pediococcus cerevisiae, and pediococcus 
pentosaeceus; propionibacterium such as propionibacterium shermanii and 
propionibacterium freudenreichii; leuconostoc such as leuconostoc 
mesenteroides ssp. cremoris and leuconostoc mesenteroides ssp. 
dextranicum; and lactobacillus such as lactobacillus acidophilus and 
lactobacillus bulgaricus. Other nonspecific bacillus type organisms of 
compost and soil origin also are candidates. 
Urease negative strains belonging to the genus lactococcus, streptococcus, 
pediococcus, propionibacterium, leuconostoc, lactobacillus, and 
non-specific unidentified bacillus type urease negative organisms of 
compost and soil origin were propagated in sterile nutrient medium. The 
cultures were transferred thrice to activate the cellular metabolism. A 
sterilized 12% solids medium was prepared by heating it to 170.degree. F. 
to 190.degree. F., holding for 45 minutes to 1 hour, and cooling to 
90.degree. F. The organisms were inoculated into this 12% solids medium. 
The amount of inoculum used was one percent. The cultures were incubated 
and neutralized at specific intervals to maximize the cell population. At 
the end of the growth period, the cultures were cooled to 40.degree. to 
50.degree. F. Then all the liquid cultures were blended and mixed with dry 
base consisting of vegetable flour, carbohydrates, vegetable gum, and 
sodium montmorillonite. After it is mixed, the entire doughy mass is 
extruded cold and dried at room temperature. Notably, this preparation 
includes the spent growth medium and byproducts of growth, such as 
bacterial enzymes and other beneficial by-products. The culture 
preparation thus prepared is mixed with the smectite clay, such as sodium 
montmorillonite, to prepare a pet litter. An alternative preparation is to 
apply the liquid culture preparation, after growth stage, by spraying it 
on the smectite clay or other pet litter blend, including swelling 
smectite clays such as sodium montmorillonite. 
In the course of conducting these studies, it was discovered that the 
stimulant, yucca schidigera extract, had an exceptional stimulatory effect 
on the urease negative bacteria, especially on propionibacterium species. 
This result was determined using direct microscopic examination. However, 
even urease negative bacteria cultures grown in growth medium without 
yucca schidigera extract exhibited odor inhibition in pet litter. A 
control medium without any bacteria, but with yucca schidigera extract, 
even when used at high concentration, could not inhibit odor in pet 
litter. Urease negative bacteria grown in the presence of yucca schidigera 
extract exhibited significantly better ability to inhibit odor in pet 
litter, as compared to urease negative bacteria grown without this 
stimulant. Possibly the exceptional growth of bacteria in the presence of 
yucca schidigera extract leads to production of significantly different 
bacterial byproducts. When the relative quantities of other ingredients in 
the growth media were varied, no similar advantage was found. 
The term "treated litter" and the like will be used throughout to refer to 
pet litter of any description to which urease negative organisms have been 
applied, unless context indicates otherwise. 
The term, "untreated litter" and the like will be used throughout to refer 
to pet litter of any description to which urease negative organisms have 
not been applied, unless context indicates otherwise. 
The terms, "beneficial organisms," "beneficial culture" or the like, refer 
to urease negative bacteria or cultures of same, unless context indicates 
otherwise. 
The terms, "culture preparation," "bacterial preparation," "bacterial 
enzyme culture additive" or the like refer to a urease negative bacteria 
in combination with spent growth medium and growth by-products, such as 
enzymes and, optionally depending on context, solidifying and bulking 
agents, unless context indicates otherwise. 
EXAMPLE 1 
A culture preparation for application to pet litter is prepared by first 
formulating a basic nutrient medium. Suitable ingredients include a 
protein source, such as sweet whey, casein hydrolyzate, and autolyzed 
yeast extract; a carbohydrate source, such as dextrose; buffers, such as 
disodium phosphate, monosodium phosphate, and sodium and bicarbonate; 
stimulants, such as powdered yucca schidigera extract; and water. A 100 
lb. mixture of medium is prepared from the following ingredients, 
expressed as weight percent. 
TABLE 1 
______________________________________ 
Typical Preferred 
Ingredient Percentage 
Range Range 
______________________________________ 
Sweet Whey 63.0 50-75 60-65 
Autolyzed Yeast Extract 
5.0 2.5-7.5 3-5 
Dextrose 20.0 10-30 15-25 
Disodium Phosphate 
1.5 1-3 1.25-2.75 
Monosodium Phosphate 
3.0 2-5 2.5-4.0 
Casein Hydrolyzate 
5.0 2.5-7.5 3-5 
Powdered Yucca Schidigera 
0.50 0.05-2.5 0.25-0.75 
Extract 
Sodium Bicarbonate 
2.0 1-5 1.5-3 
______________________________________ 
The ingredients are thoroughly blended and may be stored in dry form until 
ready for use. 
A liquid culture is prepared by reconstituting the medium at the rate of 
12% solids by weight in warm water. Next, using acid or base neutralizer, 
pH is adjusted to 6.8 to 7.0. The medium is heated with constant agitation 
to 190.degree. F. and held at that temperature for 40-45 minutes. Then the 
medium is cooled to 90.degree. F. and inoculated with individual urease 
negative strains of lactococcus lactis ssp. cremoris, lactococcus lactis 
ssp. lactis, lactococcus lactis ssp. lactis bio var diacetylactis, 
pediococcus cerevisiae, pediococcus acidilactici, pediococcus 
pentosaeceus, streptococcus faecium, propionibacterium shermanii, 
propionibacterium freudenreichii, leuconostoc mesenteroides ssp. cremoris, 
leuconostoc mesenteroides ssp. dextranicum, lactobacillus acidophilus, 
lactobacillus bulgaricus, and non specific urease negative compost and 
soil origin, unidentified mixed flora. The organisms are allowed to grow 
until pH drops to 5.8. Then, the cultures are neutralized to pH 6.2 using 
an alkaline neutralizer such as sodium hydroxide, potassium hydroxide, or 
ammonium hydroxide. The process is continued, often ten to fifteen times, 
until the pH no longer drops below pH 5.8. At this stage, most of the 
nutrients are exhausted, and a sufficient population is established in the 
medium. The live cell count concentration at this stage is approximately 2 
to 5 billion organisms per gram. 
Next, the medium is cooled to 50.degree. F. by circulating cold water 
through cooling tubes. The fully grown liquid culture is blended in a 
separate vessel with dried vegetable flours or vegetable flour and 
bentonite or other suitable dry material to bring it to a doughy 
consistency, thereby producing a culture preparation. The culture 
preparation is extruded, dried, and milled to the consistency of granules 
or fine, 200 mesh powder. 
The dried bacterial preparation is blended with smectite clay or other 
suitable granular absorbent to form a treated pet litter. The dried 
bacterial preparation can be supplied as an independent additive, to be 
mixed with any selected pet litter, such as by a pet owner or pet litter 
supplier. Similarly, the bacterial preparation can be mixed with a 
suitable absorbent material and supplied as a treated pet litter product. 
It is similarly possible to offer a treated pet litter in a package that 
also serves as a litter box. 
These organisms have been tested individually and in combinations at the 
rate of 0.1% to 5% by weight in sodium bentonite. In a preliminary 
qualitative test, 300 gm samples of treated litter were prepared. Cat 
urine, from veterinary supply sources, was added to each sample, and the 
samples were allowed to sit at room temperature for a period of three 
weeks. Equivalent control samples consisted of untreated bentonite. A 
three member panel evaluated odor of all aged samples. The result was that 
the samples treated with urease negative bacteria had less odor than the 
control samples. Samples using a combination of two species of urease 
negative bacteria showed still lower odor. Samples treated with urease 
positive bacteria were found to have powerful odor, stronger than the 
control samples. 
Based upon this preliminary showing of efficacy, further tests were run to 
determine field efficacy and acceptance by animals and humans. All tests 
were conducted using the culture prepared according to Example 1. 
EXAMPLE 2 
Qualitative efficacy tests were conducted. A seven to ten day test of 
animal absorbents, with and without the beneficial culture, was run in 
households having cats. Sample A was ordinary sodium bentonite cat litter; 
Sample B was sodium bentonite treated with 1% by weight of a culture 
preparation of beneficial organisms, as prepared in Example 1. This high 
level of a preparation of these organisms was used to determine whether 
high levels would be accepted by cats. Seven households returned bags of 
cat wastes removed from litter boxes of each sample. All cats used both 
samples, showing that litter containing the culture preparation was 
accepted. Based on weights of the returned bags of wastes, most of the 
cats preferred B. 
TABLE 2 
______________________________________ 
CAT DROSS COLLECTION DATA 
WEIGHT WEIGHT 
SAMPLE A SAMPLE B NUMBER OF 
(lbs.) (lbs.) CATS PREFER 
______________________________________ 
3.6 4.0 2 B 
0.8 1.1 1 B 
2.4 6.0 3 B 
1.3 1.5 1 B 
0.8 1.3 2 B 
3.8 5.1 3 A 
3.8 4.0 2 A 
TOTAL: 18.0 
21.5 14 -- 
______________________________________ 
Further tests were conducted on the urine soaked clumps from the waste 
collection bags: 
ODOR TEST: Samples A and B each consisted of a collection of variously aged 
specimens, ranging from 0-10 days old. Each collection was kept in a 
bucket, and the odor from the bucket was evaluated in gross. The urine 
clumps of Sample A were pungent, repulsive, and ammoniacal. The urine 
clumps of Sample B had a mild fermentative, non-repulsive odor. This 
result shows field efficacy. 
CLUMPABILITY TEST: At the time of collection, clumps from both Sample A and 
Sample B were cohesive and non-friable when collected daily. The aged 
clumps were different. Clumps from Sample A were cohesive and non-friable; 
clumps from Sample B were slightly less cohesive and slightly more 
friable. This result shows that a reaction occurred, induced by the 
beneficial cultures. 
AMMONIA TEST: The more aged specimens from Samples A and B were evaluated 
for ammonia content. Clumps weighing 30 grams were placed in petri dishes 
and 30 ml of hydrogen peroxide solution was added to each. The peroxide 
solutions from Sample A litter frothed vigorously. The peroxide solutions 
from sample B litters did not froth. This suggests that ammonia was 
present in Sample A clumps but not in Sample B. Either the urea in Sample 
B was fixed and did not form ammonia, or, if ammonia was formed, it was 
utilized by the beneficial cultures. This test was confirmed by using pure 
ammonia and pure urea. The ammonia samples frothed in the presence of 
peroxide, while the urea sample did not, indicating that it was the 
ammonia in Sample A that caused frothing. 
NON-CLUMPING LITTER TEST: A one week test was run, with and without the 
beneficial organisms, on a commercially available non-clumping litter to 
determine the efficacy of the treatment in situations where urine could 
run through the litter and pool at the bottom of the litter box. Sample C 
was untreated and Sample D contained 1% by weight of a culture preparation 
of beneficial organisms. After three cats had used the samples for one 
week, urine odor from Sample C was notably stronger than that from Sample 
D. This result indicates that the beneficial organisms are useful with 
non-clumping litters. 
CONCENTRATION TEST: Sample E was prepared by mixing ten pounds of sodium 
bentonite litter with five pounds of Sample B, producing a 0.33% 
concentration of a culture preparation of beneficial organisms. The odor 
of Sample E was substantially reduced as compared to the odor of Sample A. 
AGING TEST: The ammonia test was performed on both fresh and aged, treated 
litter. 
a. Fresh: Very fresh urine clumps--less than 8 hours old--were taken from 
three different fitter boxes. Sample A, Sample B, and Sample E. The 
ammonia test was performed. No foaming was observed in any sample, 
indicating that urea had not yet converted to ammonia. 
b. Aged: An ammonia test was run on a one week old clump from the Sample E 
litter box. The sample bubbled vigorously indicating that urea had 
converted to ammonia. This result demonstrates that urea fixation is 
stable for less than one week. Eventual breakdown is valuable in convening 
wastes to usable fertilizer. 
CONTROL TEST: 
a. Beneficial Organisms: The ammonia test was run on 100% culture 
preparation of beneficial organisms. Only an occasional bubble was 
observed, indicating that the culture preparation alone does not interfere 
with the foaming/nonfoaming test results. 
b. Urine: The ammonia test was run on a fresh sample of human urine. No 
foaming resulted. This indicates that nitrogen is present as urea and 
later changed to ammonia. 
FECAL MATTER TEST: The ammonia test was run on fresh, less that 8 hours old 
fecal matter from Sample A and Sample B litter boxes. Sample A foamed 
vigorously with a brown foam. Sample B had a few tiny bubbles and no 
foaming. This indicates that the beneficial organisms are retarding the 
formation of odor causing nitrogenous compounds in cat feces, helping with 
odor control. 
It is generally known that the primary odor causing component in cat urine 
is ammonia, formed by the breakdown of the urea in fresh cat urine. The 
odor in cat feces is from skatole and indole. In order to track the 
formation, growth, and disappearance of these and other compounds, cat 
urine and feces from Sample A and Sample B, as well as the culture, 
itself, and both the treated and untreated sodium bentonite, itself, were 
tested with sensitive instruments. It was found that skatole and indole 
were not detectable by the instruments at the levels found in litter 
boxes. Apparently, the concentration of these compounds was too low for 
analytical detection. Thus, no quantitative tests could be conducted on 
these compounds. Instrumental analysis is useful within concentration 
limits measured in parts per million. However, the human nose appears able 
to detect certain odors in concentrations of parts per billion. 
Qualitative tests, using the human nose, showed that litter treated with 
beneficial organisms was effective in reducing odors of skatole and 
indole. 
EXAMPLE 3 
The following samples were evaluated: 
Sample A--untreated Na Bentonite litter. 
"A" Urine--from untreated Sample A one day old. 
"B" Urine--from treated Sample B one day old. 
The determination of ammonia by Potentiometric, Ion Selective Electrode was 
performed according to EPA Method 350.3-1974. Approximately 25 grams of 
the sample was broken up and placed onto a fritted glass funnel. The 
sample was placed in a closed system and purged with nitrogen at fifty 
milliliters per minute for twenty minutes. The gas was purged through 110 
ml of slightly acidic deionized water which was then tested for ammonia 
with EPA Method 350.3 
TABLE 3 
______________________________________ 
QUANTITATIVE TEST FOR AMMONIA 
SAMPLE ID CONCENTRATION OF AMMONIA 
______________________________________ 
Sample A -- litter only 
0.017 mg/L 
"B" Urine - treated 
0.026 mg/L 
"A" Urine - untreated 
0.087 mg/L 
______________________________________ 
Reliable detection limit for this method is 0.05 mg/L. 
The EPA Method 350.3 analysis indicated a difference in the ammonia 
concentration observed in the samples. Measurements of ammonia level in 
the blank litter and in the urine from the treated litter were below the 
reliable detection limit of the instrument, which could introduce 
inaccuracy in the reported levels of ammonia. Nevertheless, the results 
indicated a quantitative difference. The untreated urine showed an 
increasing ammonia concentration in a 25 gram sample. 
EXAMPLE 4 
Blank specimens of both Sample A, untreated blank litter, and Sample B, 
treated blank litter, were evaluated as controls. To determine 
quantitative performance of the culture, progressively aged urine samples 
from both batches of litter were evaluated on a day-to-day aging basis 
over an elapsed period of two weeks. The freshest samples were less than 8 
hours old, having been taken on the day of the test. Further samples were 
aged each day from two to six days. Two samples from each group were 
allowed to age eight more days and were tested when they reached 12 and 14 
days aging. 
The determination of ammonia by Potentiometric, Ion Selective Electrode was 
performed according to EPA Method 350.3-1974. Approximately 40 grams of 
the sample was broken up and placed onto a fritted glass funnel. The 
sample was placed in a closed system and purged with nitrogen at fifty 
milliliters per minute for twenty minutes. The gas was purged through 50 
ml of slight acidic Nano-pure water which was then tested for ammonia with 
EPA Method 350.3. 
TABLE 4 
______________________________________ 
QUANTITATIVE TEST FOR AMMONIA 
SAMPLE B SAMPLE A 
TREATED NH.sub.3 .mu.g/g 
UNTREATED NH.sub.3 .mu.g/g 
______________________________________ 
Control 0.01 Control 0.02 
Day 1 0.36 Day 1 3.61 
Day 2 0.26 Day 2 4.77 
Day 3 11.6 Day 3 1.83 
Day 4 4.77 Day 4 136.0 
Day 5 186.0 Day 5 641.0 
Day 6 7.23 Day 6 1,777 
Day 12 1,890 Day 12 2,847 
Day 14 2,320 Day 14 2,435 
______________________________________ 
The data for the first six days was placed on a graph and a line of best 
fit was drawn for both treated and untreated samples. The graph shows a 
difference in the ammonia concentration observed in the samples. The 
treated samples showed a lower ammonia concentration as compared to the 
untreated samples from day to day. The ammonia concentration shows an 
increase from day to day in both treated and untreated samples. 
The data for days 12 and 14 are not graphed. The lower result for the 
ammonia content of the untreated sample aged 14 days as opposed to the 
untreated sample aged 12 days may be due to depletion of the urea. 
These results derived from the graph show that the urease negative 
organisms delay the formation of ammonia at the level of human olfactory 
detection, which is about 20 ppm or 20 .mu.g/g, by about two additional 
days. In an untreated litter box, this threshold level is reached in two 
to three days. In the treated litter box, the threshold level is not 
reached until almost five days. 
EXAMPLE 5 
It is desirable to determine the effective concentrations of the culture. 
The culture is more costly than typical litter such as bentonite. 
Therefore, the cost of adding the culture to untreated litter might 
influence the price of litter in a substantial fashion. Since cat litter 
generally is an inexpensive, disposable commodity, it would be desirable 
know the minimum useful level of the culture. 
Six litter boxes were prepared with ten pounds of granular bentonite and 
culture preparation. The culture preparation was pulverized in a blender 
and further crushed with a mortar and pestle. A postage scale was used to 
weigh the culture preparation; for smaller dosages, estimates were done by 
volume. For example, 0.1% was 1/10th the volume of 1%. One box was used as 
a control (0% culture preparation). The other boxes were dosed with: 2%, 
1%, 0.50%, 0.25%, and 0.10% dried culture preparation. Four cats had free 
access to the six litter boxes; not all boxes were used each day. Urine 
sample clumps were scooped daily and placed in labelled, unsealed plastic 
bags. The unsealed bags were placed in a five gallon bucket. So that each 
bag was exposed to air, the bucket lid was left ajar. The control samples 
were kept in a bucket separate from the treated samples to avoid cross 
contamination of ammonia. 
The samples were subjected to the Ammonia Test of Example 1. Bubbling of 
the peroxide/urine clump sample indicates the presence of ammonia. No 
bubbling indicated the absence of ammonia. A few tiny bubbles indicated a 
small amount of ammonia. Many bubbles and swelling of the sample with air 
bubbles indicated a significant amount of ammonia. The results of the 
Ammonia Test are reported in Table 5 with the following symbols: 
+=foamed 
-=no foam. 
The Odor Test of Example 1 was conducted by sniffing the sample clumps. The 
results are reported in Table 5 with odor rated as follows: 
-=could not perceive ammonia 
+=slight ammonia odor 
++=moderate ammonia odor 
+++=strong ammonia odor 
TABLE 5 
__________________________________________________________________________ 
AMMONIA AND ODOR TEST RESULTS 
Culture 
Control - 
Age of 
0% 2% 1% 0.5% 0.25% 0.1% 
Sample 
NH.sub.3 
Odor 
NH.sub.3 
Odor 
NH.sub.3 
Odor 
NH.sub.3 
Odor 
NH.sub.3 
Odor 
NH.sub.3 
Odor 
(day) 
Test 
Test 
Test 
Test 
Test 
Test 
Test 
Test 
Test 
Test 
Test 
Test 
__________________________________________________________________________ 
1 - - - - - - 
2 + + - - - - 
3 + + + - + - + - + - - - 
4 + +++ + - + + - - + - 
5 + +++ + - + - + - - - 
__________________________________________________________________________ 
Blank indicates sample box was not used on that day. 
The culture treated samples had a mild, yeasty odor. The fragrance of the 
culture itself could be detected in the samples having the higher dosages. 
The data shows the culture preparation to be effective in retarding 
formation of ammonia down to 0.1%, which was the lowest level tested. 
After five days, all samples treated with the culture preparation had no 
ammonia odor. The peroxide test for ammonia, when applied to the treated 
samples, showed no response on days one and two and a slight response or 
no response on days 3 to 5. 
It is believed that a smectite clay mineral with sodium as the dominant 
cation associated with the exchange sites of the smectite, is especially 
suited to serve as a buffer means for pH control in a clumpable pet 
litter. Sodium montmorillonite, also known as sodium bentonite or Wyoming 
bentonite, is a readily available and widely accepted example of such a 
smectite clay. Other suitable buffer systems might employ mixtures of 
salts and acids of carbonate, phosphate or borate anions. When liquid is 
imbibed by the pet litter to form a clump, the sodium smectite or other 
buffer means additives will create a pH greater than 7 and approximately 
pH of 9 for optimum effect. 
A solution that contains a weak acid or base plus the salt of that acid or 
base is known as a buffer. Buffer mixtures regulate the pH of an aqueous 
solution so that, when acid or base is added to the system, there is only 
a small change in the pH of the system. 
In the combination of clumping pet litter and dried urease negative 
bacterial enzyme culture additive, the sodium bentonite provides a 
desirable buffer property to pet litter in addition to its clumping 
property when exposed to acidic pet urine. The buffering effect of sodium 
smectite clays or inorganic carbonate, phosphate and borate buffer 
additives maintains a neutral or basic pH in the urine clump. The basic pH 
of the urine clump provides the appropriate conditions to favor growth of 
the urease negative bacterial enzyme culture additive and to inhibit the 
growth of urease positive bacteria from the environment. 
EXAMPLE 6 
In order to determine buffering action of pet litter, three pet litter 
materials were evaluated for pH over seven days of use by three cats. The 
first product was pure sodium bentonite. The second was commercially 
available Scoop Away litter, a product of A&M Products. The composition of 
Scoop Away is about 50% sodium bentonite and 50% other clays and chemical 
additives. The third was commercially available Fresh Step litter, a 
product of Clorox Corporation. Fresh Step is known to contain attapulgite 
clay and may contain fuller's earth, as well. Each of these three 
materials was tested in both untreated and treated versions. The treated 
materials contained 0.5% by weight of the culture preparation. The six 
samples were tested for pH both when the samples were gathered and after 
the gathered samples were aged over a time period ranging from zero days 
to six additional days. The pH of a control sample of each material, which 
was not used by the cats, was measured initially to determine a base 
reading and was evaluated again after six days aging. 
TABLE 6 
__________________________________________________________________________ 
pH OF PET LITTER OVER SEVEN DAY PERIOD 
Treated 
Sodium 
Sodium 
Scoop 
Treated Scoop 
Fresh 
Treated Fresh 
Sample Day 
Bentonite 
Bentonite 
Away 
Away Step 
Step 
__________________________________________________________________________ 
Control - 
9 9 7.5 7 8.5 8.5 
fresh 
Control - 
9 9 7.5 7 8.5 8.5 
6 days 
Day 0 - fresh 
8 8.5 7.5 8.5 8.5 8.5 
Day 0 - aged 
8 8.5 7.5 8 8.5 8.5 
Day 1 - fresh 
8 8.5 7 7.5 9 8.5 
Day 1 - aged 
7.5 8.5 7 8 8 8.5 
Day 2 - fresh 
8 8.5 8 9 8.5 
Day 2 - aged 
8 8.5 8.5 8 8.5 
Day 3 - fresh 
9 7.5 8 
Day 3 - aged 
8 7 7 8 
Day 4 - fresh 
8.5 7 7.5 
Day 4 - aged 
8.5 7 7 
Day 5 - fresh 
8.5 8.5 8 
Day 5 - aged 
8 7.5 8 
Day 6 - fresh 8 
Day 6 - aged 8 
__________________________________________________________________________ 
On days showing a blank, the particular sample was not used. 
The test results show that sodium bentonite was the most alkaline control 
material, with pH 9. Fresh exposure to cat urine caused a drop in the pH 
of untreated sodium bentonite to either pH 8 or pH 8.5. With age, the 
samples showed very little change. In two cases the sample pH dropped 
slightly. Buffering appeared to be effective and the pH stabilized in the 
range from 7-9. The treated sample of sodium bentonite showed relatively 
less pH drop and remained relatively more stable, indicating a better 
buffering action. 
Untreated Scoop Away had a lower control pH of 7.5. Fresh exposure to cat 
urine caused mixed results, with some samples showing a pH drop and 
another showing a rise. Sample aging had substantially no effect on pH, 
except that the sample with initial higher pH rose a bit with age. Treated 
Scoop Away started with a still lower control pH of 7. It showed both 
increases and decreases in pH with both fresh and aged exposure to cat 
urine. Buffering appeared to be effective and pH remained in the range 
from 7-9 in all samples. 
Both treated and untreated control samples of Fresh Step had an 
intermediate control pH of 8.5. With fresh exposure to cat urine, both 
samples of Fresh Step had a stable pH that changed only slightly, if at 
all, from the control value. All samples of all three pet litters 
maintained pH in the range from 7-9 throughout the tests, which 
established that the buffering action of the smectite clay is sufficient 
to maintain the pet litter in the desired pH range at least through the 
effective period of the culture. 
The preferential growth of urease negative bacteria inhibits the bacterial 
conversion of urea to ammonia by urease positive bacteria from the 
environment. Ammonia is the major odor component of the urine clump. If 
the pH of the urine clump becomes acidic, urease positive bacteria can 
grow and will generate ammonia from urea with a consequent odor. The 
buffer and urease negative bacteria culture stabilizes the urea for 
approximately three extra days, to a total of about five days, until 
urease positive bacteria eventually invade the urine clump and begin 
generation of ammonia and odor. 
The foregoing is considered as illustrative only of the principles of the 
invention. Further, since numerous modifications and changes will readily 
occur to those skilled in the art, it is not desired to limit the 
invention to the exact formulation and operation described, and 
accordingly all suitable modifications and equivalents may be regarded as 
falling within the scope of the invention as defined by the claims that 
follow.