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Eastern Academic Journal ISSN: 2367 – 7384
Issue 4, pp. 78-86, December 2019
Corresponding author at: Trakia University, Faculty of Agriculture, Stara Zagora, Bulgaria, e-mail: syl_rad@yahoo.com
BIODEGRADABLE PLANT BASED CAT LITTER FILLERS –
RELEVANCE OF THE TOPIC IN BULGARIA
Silviya S. Radanova
Trakia University, Stara Zagora, Bulgaria
–––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––
ABSTRACT: The appearance of biodegradable cat litters is a regular stage in the development of human-
nature relationships, an expression of our concern for the difficult survival of this tiny, dared to enter human
settlements predator. The article analyzes the plant species used as a basis in cat litter to attract public attention
to the problem of the ecological utilization of plant and animal waste. Biodegradable cat litter mats are one
solution to how waste products from diverse industries and agriculture can be used to improve the welfare of our
pets.
Keywords: cat litter filler, biodegradation, plant species, pets welfare
––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––
1. INTRODUCTION
The domestic cat (Felis silvestris catus) has long been a part of our lifestyle with its unintrusive
presence. It is proud to carry out its millennial mission as a small predator - to cope with rodent
populations around barns and warehouses in human settlements (Vigne et al. (2004); Driscoll et al.
(2007). The urban environment in cities increasingly imposes the difficult role of cats as pets that
depend entirely on its owner (Palmer & Kasperbauer, 2018). Although the definition raises many ethical
issues, dilemmas and conflicts, the number of households growing more than one pet increases
(AVMA. 2012). It is true that keeping animals at home can be expensive and inconvenient, but for
many people the benefits of living together are so significant that they outweigh the costs (Serpell &
Paul 2011). Research shows that owners are highly attached to their satellites and invest significant
resources in caring for them. Accompanying animals support a massive industry - in the US alone in
2014, estimated expenditure was $ 58.51 billion for production of specialized foods, toilets and
accessories, veterinary care and services (APPA 2014).
One of the main problems associated with the nurture of the species indoors is the places of
excretion of its metabolic waste - cat litters. As an obligatory predator that feeds on meat, cat urine is
highly concentrated, with high levels in urea, creatine, uric acid, sodium chloride, and electrolytes.
When the cat's litter is not cleaned on time, the bacteria that break down its components begin to act in
stages – at the beginning odor of ammonia appears, and subsequently the increasingly unpleasant sulfur
compounds - mercaptans show up (Starkenmann et al., 2015). This is one of the reasons why cats are
unwanted in shelters, chased away from home and even euthanized (Salman et al., 2000).
Eastern Academic Journal ISSN: 2367 – 7384
Issue 4, pp. 78-86, December 2019
79
The history of cat toilets is the work of surveyors, biochemists and mining engineers, and of
course, of coincidence. Until the middle of the last century, cats were kept warm only in winter, and the
cellars were filled with ash from fireplaces or sawdust, which they used as natural toilets (Goodman,
2015). In Michigan in the winter of 1947, Edward Lowe (owner of an industrial absorbent company)
changed everything. The cold winter conditions cause his neighbor to not use the frozen sand for a cat
toilet and he solves the problem by giving it dry clay pellets. Receiving positive reviews of this
accidentally discovered new cat litter filler, he is gradually turning it into business (Lowe et al., 1987).
This is how the cat litter filler industry started, and naturally, the innovation in refining it. The first are
made of clay (Fuller's Earth) with non-clumping particles. The next innovative step does dedicated
biochemist Thomas Nelson, Ph.D (Nelson, 1991). He found that crude dried clays have highly
absorbent properties and form lumps that retain moisture in them - thus creating clumping fillers for cat
litter. It was not until 2014 that John Lipscomb (Repinski, 2014) - a chemist, who created an alternative
100% grass cat litter that does not emit dust, it is biodegradable, neutralizes smells, and does not clump.
This study aims to analyze plant species used as fillers in biodegradable cat litter, connect their
morphology and histology with some of their physical and sensory properties, and to show that keeping
cats indoors can be a pleasant and environmentally friendly activity that is financially sparing owners
and improves the pet’s quality life.
2. MATERIALS AND METHODS
In July 2019, 20 pet shops were randomly crawled on the territory of Stara Zagora and a survey
was conducted on the types of fillers for cat litter. On-line information about the offered products in the
big cities - Sofia, Varna, Bourgas, and Plovdiv was made. Primary information was collected for the
territory of Stara Zagora - directly from the source: seller-consultants (in many cases with veterinary-
medical education or having contact with clinical base). A short survey was also conducted with two
standard questions: are there plant-based cat litters available, and if there are pellets in the store (mainly
for rodents) - are buyers informed that they can also be used for cats? The online survey includes
secondary data collected from Internet sites, and patents filed in the Google Patents system. The results
obtained are interpreted from a botanical and biochemical view point.
Cited patent information is protected by US Constitution, US Patent and Trademark Office
(USPTO), World Trade Organization (WTO), and at European level - by European Patent Convention
(EPC). Other levels for patent protection are the Guidance of Paris Convention for Protection of
Industrial Property (PIP) (1883) and Patent Cooperation Treaty (PCT) (1970), administered by World
Intellectual Property Organization (WIPO) and covering more than 150 countries, with Bulgaria among
them. The clauses and subparagraphs of these documents shall be updated periodically.
Eastern Academic Journal ISSN: 2367 – 7384
Issue 4, pp. 78-86, December 2019
80
3. RESULTS AND DISCUSSION
Results of the survey, conducted on the territory of Stara Zagora and on -line reference for our
country are summarized in Table 1.
№
Pet store
Address
Type of cat litter
1
Pet store
29 “ Tsar Simein“ Str.
Bentonite, Silica gel, Bentonite
scented
2
Pet store
„Friends“
42 “I.Garvanov“ Str.
Bentonite, Silica gel
3
Pet store
137 “Mayor Kavaljiev “ Str.
Bentonite, Silica gel
4
„ City Tails "
177А “ Mayor Kavaljiev“
Str.
Bentonite, Silica gel,
Biodegradable soybean & corn
pellets
5
Pet store
129 “Tsar Ivan Asen“ Str.
Bentonite – natural and scented
6
Pet store
51“Parchevich “ Str.
Bentonite – natural and scented
7
Zooland
115 „ Kniaz Boris“ Str.
Bentonite, Silica gel
8
Veterinary
pharmacy
49 “Geo MIlev “ Str.
Bentonite, Silica gel
9
Pet store
139 “Hristo Botev “ Str.
Bentonite, Silica gel,
Pellets from Juniper, cellulose,
fiber & bulk
10
„Vereia Vet“
43 “D. Naumov“ Str.
Bentonite, Silica gel
11
Pet store
35 “Sava Silov“ Str.
Bentonite, Silica gel,
Bentonite scented
12
Pet store
75 “Mayor Kavaljiev “ Str.
Bentonite, Silica gel
13
Pet store
„Tedy“
9 „Capt. P. Voivoda“ Str.
Bentonite, Silica gel,
Bulk for rodents
Eastern Academic Journal ISSN: 2367 – 7384
Issue 4, pp. 78-86, December 2019
81
Table 1. Pet stores visited
The analysis of available cats toilet in pet stores visited shows three main types of cats
litter filler:
1. Clumping - from natural clays (sodium bentonite) - natural or scented
2. Non-clumping - from silica gel or calcium bentonite - natural or scented
3. Biodegradable (plants based) - clumping in different levels - containing parts of stems,
leaves, seeds and fruits; in the form of pellets or granules, natural or flavored, of the following plant
species: pine, juniper, cedar, soybean, wheat, maize, coconuts, coffee, green tea, bamboo, citrus fruits,
box and recycled paper (pulp).
A survey conducted in the Stara Zagora sales network reveals that biodegradable cat toilets are
increasingly being used (50% of pet stores already offer one or more items), although they are sought
after by a small number of customers. On-line space in our country offers more choice related to
established import brands. The author is not a specialist in the field of market economy and does not
comment on prices, but is aware of one of the basic principles of marketing - that the situation on the
14
„Zoostop „
Pet store
23 “А. Batenberg “ Str.
Bentonite – natural and scented ,
Biodegradable soybean & corn
pellets
15
Pet store
„Effect“
31 “Iskar“ Str.
Bentonite – natural and scented ,
Silica gel , Biodegradable fiber
pellets
16
Pet store
“Lorka“
4 „Slavianski„ Blv.
Bentonite – natural and scented ,
Silica gel – natural and scented,
Biodegradable soybean, corn,
green tea & coffee pellets
17
Pet store
„Luki“
60 “Avgusta Trajana“ Str.
Bentonite, Silica gel
Biodegradable – 5 types + bulk
18
Pet store
„Feniks“
9 “Stara planina“ Str.
Bentonite, Silica gel +
Biodegradable soybean
19
Pet store “D-r
Kollev“
96 “Tsar Ivan Shishman“ Str
Bentonite, Biodegradable –
from maize + bulk
20
„Royal pets”
77 “D. Naumov“ Str
Bentonite, Biodegradable –
pellets from coniferous and
deciduous species + soybean
Eastern Academic Journal ISSN: 2367 – 7384
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internal market must correspond to the situation on external one. This makes the quality items too
expensive, which significantly limits the ability to house more pets in homes, shelters, etc.
The ubiquitous replication of biodegradable nature of plant based cat litters seems to contrast to
those based on classical clays. In fact, both types of fillers have natural origin. Different types of clays
come from volcanic ash and if decomposed, today there would be no fine porcelain products, stable
buildings, steel and foundry, wine, etc. (Murray, 2000). Plant residues break down over for different
periods of time, but in any case it is less than the disintegration of artificial materials. Along with
organic waste, they can be used as a compost in the garden once more (MOEW, 2010).
It is well-established practice in the developed countries to produce statistics every year, incl. to
the consumption of mineral deposits, which, like fuels, are not inexhaustible (Hosterman, Patterson,
1992). Current study on the consumption of cat litters (2014) shows, that 72% of buyers prefer bentonite
clay, 16% non-clumping clay, 9% silica gel, and 12% buy plant-based toilets. One of the major reasons
for the biodegradable cat litters appearance is the environmental impact of their precursors – the clay
based litters. The way clay is extracted - in strips that disrupt habitats - is discussed, as well as the fact
that it is not biodegradable. According to a US Geological Survey in 2011, of the 4.68 metric tons of
bentonite excavated, 1.11 metric tons are involved in the production of cat litter and the used clay waste
is dumped directly into landfills no recyclable.
From botanical view point, plant sources used as fillers for cat litter can be divided into four
groups:
1. Stems
from woody species – waste bark and wood are used
In tree species, cellulose cell walls are thickened and hydrophobic waxy - like compounds are
postponed between them: suberin (45%), lignin (27%), tannins (6%), waxes (5%) and other substances
(5%), summarized as cork (Silva et al., 2005). Cork is an inert material impermeable to gases and water,
also retains neutrality of taste and odour, and does not absorb odours. If the wood is from coniferous
(pine, spruce, cedar, juniper, cypress), there are resin-filled essential oil cavities situated between the
cells. Also available on the market are pellets of deciduous species - beech, oak etc. Raw bark and
wood contain tannins, polyphenols, sterols, organic acids and flavonoids (Ciurlea еt al., 2010; Raju еt
al., 2007). For both wood types, the pellets must be thermally treated and dried several times to remove
moisture and bioactive substances that may be toxic to cats. When used, the pellets turn into sawdust,
swell, but do not stick together, easily separated from the paws without risk of ingestion.
from grass species - grasses (Poaceae Family) – stems and rarely leaves
For bedding, the stems (the straw) of cereals after harvesting are used - wheat, rye, barley, oats,
which are dry and easy to process due to the thin cellulose cell walls. Indoor cats spend up to 30% of
their day caring for their fur, licked hair is often collected in balls and causing constipation in the
digestive system (Benjamin, 1976; Panaman, 1981). Outdoors, cats instinctively orient themselves to
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83
the leaves of cereals, which normalize their peristaltic. Similar will be their reaction at home with
stomach problems as well. An inappropriately selected and poorly processed cereal substrate in the cat's
toilet can become a problem, especially for small kittens. Cat litters, made from recycled paper
(cellulose) are not among the most preferred because of the high cost and frequent replacement
necessity. Cellulose fibers absorb water and swell, but does not form lumps.
The water content of the leaves is much higher, as is the amount of biologically active
substances, so they are not a preferred substrate for cat litter, but are mainly used for feed. An exception
is made for leaves of species grown massively in culture for other purposes - cosmetics, medicine, etc.,
which are leather (tea) or fleshy (aloe) and unsuitable for animal feed.
2. Fruits and fruit parts - the dry woody parts of the fruit are used - pits, shells, pods, sunflower
husks, etc. (nuts, peanuts, soybean and bean casings) made from mechanical tissues, named sclereids.
They are dead at maturity and have corky cell walls. Cat litters, made from this material, is not
clumping. The pulp, obtained from the processing of fruits and vegetables - tomatoes, beets, oranges, a
rich of starch.
3. Seeds and seed parts - mainly seeds of grasses and legumes are used (Poaceae & Fabaceae
family) - wheat, maize, soybeans, etc., grown as major crops in the temperate zone. The seeds are rich
in starch, which captures moisture and easily forms lumps (Bietz & Lookhart, 1996; Vaughn еt al.,
2011). It has been found that during the production process maize pulp can become infected with molds
(Park et al., 2018), which, even treated, retain their toxicity in the cat toilet. Often the core and whole
cob of seeds are used for production of cat litter.
4. Tropical species - depending on the latitude and specificity of the crops grown, cats' litters
include various parts of native plant species, such as: Genus Coffea (Coffee) , Cocos nucifera
(Coconut) - fruit sheaths are used; Genus Bambusa (Bamboo) - stems are utilized, Genus Citrus
(Citrus) - a citrus slurry containing residues from the fruit wall, seeds and stems are put-upon.
4. CONCLUSION
From botanical view point the use of different plant parts determines the physical and sensory
properties of the cat's litter filler. When plant organs, containing cellulose or cork (woody and grass
stems) are used for this purpose, the filler has absorbent properties but does not clump and absorbs the
smell to varying degrees. The large amount of starch in the seeds gives clumping properties of the filler.
Analysis of plant sources reveales another important pattern - local, low-cost waste products
from different industries are used. The usage of native species should take into account the seasonal
cyclicality of crops in the temperate zone. As an EU member, Bulgaria is involved in the problem of
waste management and recycling (Uzunov 2018). Every year various fields of production, such as
agriculture and forestry, aquaculture, production of ethyl alcohol, textiles, tobacco, beer, furniture and
canning, etc., emit tens of tons of plant biomass (RIEW, 2011). At the same time the latest annual data
from European Pet Food Industry Federation (FEDIAF, 2018) shows that pet ownership across Europe
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84
remains high, with an estimated 80 million European households owning at least one pet. For Bulgaria,
Statista (2018) lists 800 cats / 1000 citizens. There are no data on the number of cats bred in different
cities, but it is common practice to breed 1-3 cats. Breeders prefer cats with pedigree, sparing no means
of raising them. It is more difficult to raise cats in shelters and private homes, where the needs for food
and comfort for the animals are much greater, but resources - limited. The use of local waste material
will significantly reduce the cost of the finished product and will create the prerequisites for the greater
distribution of biodegradable cat litter in their feline life - which means that the welfare of more animals
can be increased at low costs.
5. ACKNOWLEDGMENTS
The author thanks for the kindly provided information by the consultants working at the cited
pet stores.
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