DOI: https://doi.org/10.52973/rcfcv-e32166
Received: 18/06/2022 Accepted: 16/07/2022 Published:13/09/2022
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Revista Cientíca, FCV-LUZ / Vol. XXXII, rcfcv-e32166, 1 - 8
ABSTRACT
In this study, the presence and types of urine crystals in cats and dogs
with urolithiasis/crystaluria and the effects of some demographic
factors (such as type, breed, age, sex, sterilization status) on them
were evaluated. In the study, physical, chemical and sediment
examinations of urine samples of 67 cats and dogs were performed.
It was determined that 83.58% of the animals with crystals in their
urine were male. It was determined that 63.64% of the female animals
and 44.64% of the male animals with crystals detected in the urinary
tract were sterilized. It was determined that urinary crystals were
more common in cats between 1-3 years of age (AO) and in dogs older
than 3 AO. It was determined that calcium oxalate crystal (64.41%)
in cats and struvite crystal (50%) in dogs were the most common
crystals. It was determined that urine crystals were found mostly
in cross breeds in cats and dogs. It was determined that most of
the cats and dogs with urine crystals were fed with home meals and
non-branded foods. It was determined that urinary tract infections
had an effect on the formation of urine crystals. As a result, it was
concluded that it is important in terms of Veterinary Medicine that
such studies should be routinely performed, especially in the United
States of North America (such as the Minnesota Urolith Center),
since urine crystals cause signicant lower urinary system diseases.
Key words: Calcium oxalate; cat; dog; urolite; struvite
RESUMEN
En este estudio se evaluó la presencia y tipos de cristales de orina
en gatos y perros con urolitiasis/cristaluria y los efectos de algunos
factores demográficos (como tipo, raza, edad, sexo, estado de
esterilización) sobre ellos. En el estudio se realizaron exámenes
físicos, químicos y de sedimentos de muestras de orina de 67 gatos
y perros. Se determinó que el 83,58% de los animales con cristales
en la orina eran machos. Se determinó que el 63,64% de las hembras
y el 44,64% de los machos con cristales detectados en vías urinarias
fueron esterilizados. Los cristales urinarios eran más comunes en
gatos entre 1-3 años (a) y en perros mayores de 3 a. Se determinó
que el cristal de oxalato de calcio (64,41%) en gatos y el cristal de
estruvita (50%) en perros fueron los cristales más comunes. Los
cristales de orina se encontraron principalmente en razas cruzadas
en gatos y perros. La mayoría de los gatos y perros con cristales en
la orina se alimentaban con comidas caseras y alimentos sin marca.
Se determinó que las infecciones del tracto urinario tenían efecto
en la formación de cristales en la orina. Como resultado se concluyó
que, es importante en términos de Medicina Veterinaria que dichos
estudios se realicen de forma rutinaria, especialmente en los Estados
Unidos de NorteAmerica (como el Minnesota Urolith Center), ya que
los cristales de orina causan enfermedades importantes del sistema
urinario inferior.
Palabras clave: Oxalato de calcio; gato; perro; urolita; estruvita
Microscopic evaluation and Descriptive study of Crystals and Uroliths
encountered in the Urinary tract system of Cats and Dogs
Evaluación microscópica y estudio descriptivo de cristales y urolitos encontrados en el sistema de
vías urinarias de perros y gatos
Eren Polat
1
* , Emre Kaya
2
, Münir Mert Oral
3
and Nisanur Çelikdemir
2
1
Firat University, Faculty of Veterinary Medicine, Department of Surgery, Elazig, Turkey.
2
Firat University, Faculty of Veterinary Medicine, Department of Biochemistry, Elazig, Turkey.
3
Nova Veterinary Clinic, Balikesir, Turkey.
*Email: erenpolat@rat.edu.tr
Urine Crystals in Cats and Dogs / Polat et al. ______________________________________________________________________________________
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INTRODUCTION
Crystalluria refers to the presence of crystals in the urine, which
occurs due to the oversaturation of certain electrolytes and/or,
substances and can cause an important lower urinary tract disease
such as urolithiasis. Urolithiasis is one of the important urinary system
(US) problems encountered in all animals. Uroliths are formed by the
combination of many physiological and pathological factors that cause
changes in urine composition. These physiological and pathological
factors cause saturation of some substances in the urine and their
precipitation in the Urinary System (US) [3, 5, 9, 11, 16, 17, 20, 24, 25].
Anatomical and metabolic abnormalities, US infections, malnutrition
and variability in urine pH are very important risk factors for the
formation of uroliths. Struvite crystals (SC) mostly occur in young
animals, while calcium oxalate crystals (COC) occur mostly in older
animals. It is also more common in female cats (Felis catus) and dogs
(Canis lupus familiaris) than males. This shows that factors such as
age, sex and breed are effective in the formation of uroliths [3, 4, 16,
20, 23, 24]. Determining the causes of the formation and growth of
crystals is very important in preventing urolith formation [3].
The cases of urolithiasis may differ according to the etiology and
chemical structure of the formed crystals. SC, COC, cystine (CC) and
urate urolites (UC) are the most common urinary crystals in pets [24].
According to the Minnesota Urolith Center, the most common urolite
in dogs is SC, while in cats it is COC [3, 16, 20].
SC occurs as a result of crystallization of magnesium, ammonium
and phosphate minerals in the US by reaching supersaturation. In
cases encountered in dogs, urinary tract infections caused by bacteria
producing urease enzyme (Staphylococcus spp., Proteus) and alkalinity
of urine are effective. Dietary, metabolic and genetic factors are
mostly effective in the formation of SC in cats [3, 16, 18, 20, 24].
COC is one of the most common urinary tract crystals in cats and
dogs [3, 6]. COC are more common in Schnauzer and Lhasa Apso
breeds in dogs, and Ragdoll and British Shorthair breeds in cats [6].
COC form as a result of oversaturation of the urine with crystalloids.
Hypercalciuria is the most important factor in the formation of COC.
Excessive amounts of calcium, protein, sodium, vitamin D and vitamin
C in foods are effective in the formation of hypercalciuria. Again,
diets and drugs that cause acidication of the urine are effective
in the formation of hypercalciuria. Hypercalciuria may also occur in
patients with hyperadrenocorticism [4, 6, 7, 24].
UC or purine crystals are the third most common type of crystal in
cats and dogs. UC are formed as a result of precipitation of uric acid
and uric acid salts (ammonium urate, sodium urate, sodium calcium
urate, potassium urate) in the US. It is known that especially Dalmatian
dogs and animals with portovascular anomalies are predisposed to
UC [3, 22, 24].
CC are rarely encountered in cats and dogs. Although the formation
mechanism is not known exactly, the formation of cystinuria due to
the decrease in tubular absorption of cystine taken with foods (pork
meat, poultry, etc.) creates a predisposition. However, since cystine
is an amino acid soluble in alkaline solutions, it is effective in the
formation of CC in acidic urine [24].
In this study, physical, chemical and microscopic sediment
examination of urine samples taken from cats and dogs suspected
of having uroliths and/or crystals in the urinary tract was performed.
The ratios of crystals detected in the urinary tract of cats and dogs
and their differences according to species, breed, age, sex, and
sterilization status were determined. However, in line with the
information received from the owners, some factors such as diet
and disease status of the animals with crystals in the urinary tract
were evaluated. In addition, it was aimed to evaluate the effect of
crystal types on the physical and chemical properties of urine.
MATERIALS AND METHODS
Ethical approval
This study was conducted in accordance with the principles of the
Local Ethics Committee in the framework of the ethics conrmed
by the Firat University Animal Experiments Local Ethics Committee
(20.01.2022, 2022/2, Document no: 6368).
Study design and practices
In this study, it was aimed to investigate the effect of species,
breed, diet, age and sex on the formation and type of crystals by
physical, chemical and sediment examination of urine samples of cats
and dogs with suspected urolith and/or crystals in the urinary tract.
For the study, urine samples were collected in sterile tubes during
natural urination from cats and dogs who had diculty urinating in
the Provinces of Elazig and Balikesir (Turkey). First of all, physical
(color and turbidity) and chemical (pH, blood, leukocyte, protein,
among others) examinations of urine samples were performed. An
urine analysis strip with the brand name Acon Insight Expert was used
for the chemical examination of the urine samples. After 5 mililiters
(5mL) of urine collected from cats and dogs was centrifuged at 1,500
rpm (252 G) for 5 minutes, sediment examination was performed
under the microscope (Olympus CX21LED brand light microscope,
Olympus Corporation, Japan), (crystals, erythrocytes, leukocytes,
epithelial cells, among others) [3, 16]. During the study, the samples
were evaluated by the same researcher twice by blind examination
under the Nikon Eclipse brand phase microscope (Nikon Corporation,
Japan) and the Olympus CX21LED. Conicting samples were evaluated
once again at the end of the study, both under the light microscope
and under the phase microscope.
During the study, information was collected about the diet and
general health status of cats and dogs with suspected urolith and/
or crystalluria. The effect on urolite and/or crystalluria formation
was evaluated by comparing the analytical components, nutritional
contributions per kilogram (kg) and energy values of commercial
foods. Thus, the relationship between crystal types and feeding
patterns was also evaluated. Frequencies were calculated using the
SPSS package program descriptive statistics.
RESULTS AND DISCUSSION
In this study, physical, chemical and sediment examinations of urine
samples of 67 cats and dogs with crystals detected in the urinary
tract were performed (TABLE I).
Animals with crystals in their urine; it was determined that 11.94%
were dogs (n=8) and 88.06% were cats (n=59). It was determined that
83.58% of them were male (n=56) and 16.42% were female (n=11).
Animals with crystals in their urine; it was determined that 47.76% of
them were neutered/castrated (n=32) and 52.24% were not neutered/
castrated (n=35). Urine crystals were found to be more common in
cats between the ages of 1-3 and in dogs older than 3 AO. The rates
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TABLE I
Detailed evaluations of cases with urinary crystals
Case # Species Breeds Age Sex
Neutering
Status
Blood Protein pH Density Crystal type
1 Cat Crossbreed 3 year M + 2 3 7.5 1.022 Struvite
2 Cat Crossbreed 6 year F + 3 2 7 1.022 Struvite
3 Cat Crossbreed 3 year M + 0 1 6 1.022 Uric Acid - Calcium Oxalate
4 Cat Crossbreed 4 year M - 0 3 7 1.011 Calcium Oxalate
5 Cat Crossbreed 2 year M - 4 4 7 1.022 Amorphous Biurate
6 Cat Crossbreed 2 year M - 4 3 6.5 1.033 Struvite
7 Cat Crossbreed 3 year F + 4 3 6.5 1.033 Amorphous Biurate - Calcium Oxalate - Uric Acid
8 Cat Crossbreed 3 year M + 4 3 6 1.033 Cystine- Calcium Oxalate - Uric Acid
9 Cat Crossbreed 3 year M - 3 4 7 1.033 Calcium Oxalate- Struvite
10 Cat Crossbreed 2 year F - 4 2 6 1.033 Uric Acid
11 Cat Crossbreed 5 year M - 2 4 7.5 1.011 Calcium Oxalate
12 Cat Crossbreed 3 year M - 1 2 7 1.011 Struvite
13 Cat Crossbreed 2 year M - 4 4 9 1.011 Struvite
14 Dog Bernese Mountain 8 year F + 1 0 6.5 1.011 Struvite
15 Dog Crossbreed 6 year M - 4 1 7 1.022 Calcium Phosphate
16 Cat Crossbreed 1 year F - 0 1 6.5 1.022 Cystine - Uric Acid
17 Dog Shih Tzu 3 year M + 1 0 7 1.011 Struvite
18 Cat British 3 year M - 3 3 8.5 1.022 Struvite - Calcium Oxalate
19 Cat Scottish 2 year M - 4 2 7 1.022 Struvite
20 Cat Crossbreed 4 year M - 4 3 7 1.011 Calcium Oxalate
21 Cat Crossbreed 2 year F - 1 2 7 1.022 Calcium Oxalate - Amorphous Biurate
22 Cat Crossbreed 4 year M - 2 3 7.5 1.011 Calcium Oxalate
23 Cat Crossbreed 12 year M + 4 0 6.5 1.033 Struvite
24 Cat British 1 year M - 4 2 7.5 1.022 Struvite
25 Cat Crossbreed 7 year M + 4 2 7.5 1.022 Struvite - Hippuric Acid
26 Cat Crossbreed 4 year M + 3 3 7.5 1.011 Calcium Oxalate - Calcium Phosphate
27 Cat Crossbreed 7 year M + 4 3 6 1.033 Cystine - Calcium Oxalate
28 Cat Scottish 2 year M + 4 0 7 1.044 Calcium Oxalate
29 Cat Crossbreed 1 year M - 0 3 7 1.011 Calcium Oxalate
30 Cat Crossbreed 1 year M - 4 3 7 1.022 Struvite - Calcium Oxalate
31 Cat Crossbreed 4 year M + 0 2 7.5 1.022 Calcium Oxalate
32 Cat Crossbreed 2 year M + 2 1 6.5 1.011 Calcium Phosphate
33 Cat Crossbreed 3 year F + 2 2 7.5 1.033 Calcium Phosphate - Struvite
34 Dog Pomerian 6 year F - 0 1 9 1.011 Struvite
35 Cat British 2 year M + 1 2 8.5 1.022
Calcium Carbonate
36 Dog Crossbreed 6 month M - 2 2 6 1.022 Urate – Cystine
37 Dog Jack Russel 7 year M - 0 1 7 1.033 Calcium Oxalate
38 Cat Scottish 2 year M - 4 3 7.5 1.022 Struvite
39 Cat Crossbreed 3 year M + 0 2 8 1.022 Struvite - Calcium Oxalate – Calcium Phosphate
40 Cat Scottish 2 year M - 0 2 7 1.033 Calcium Oxalate
41 Cat Crossbreed 2 year F + 0 2 8 1.022 Calcium Oxalate - Calcium Phosphate
42 Cat Crossbreed 3 year M - 3 4 8.5 1.011 Calcium Phosphate - Struvite
43 Cat Smokin 3 year M + 4 3 7 1.011 Calcium Oxalate - Acyclovir
Urine Crystals in Cats and Dogs / Polat et al. ______________________________________________________________________________________
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TABLE I cont...
Detailed evaluations of cases with urinary crystals
Case # Species Breeds Age Sex
Neutering
Status
Blood Protein pH Density Crystal type
44 Cat Crossbreed 3 year M + 4 1 5 1.033 Calcium Oxalate - Urate - Uric Acid
45 Cat Persian 4 year M + 0 2 7 1.033 Calcium Oxalate
46 Cat Persian 3 year M + 0 3 8 1.022 Calcium Phosphate - Calcium Oxalate
47 Cat Crossbreed 2 year M - 0 0 5 1.022 Uric Acid - Calcium Oxalate
48 Cat Crossbreed 2 year M + 0 2 8 1.033 Calcium Oxalate - Struvite – Calcium Carbonate
49 Cat Crossbreed 4 month M - 4 3 5.5 1.033 Urate - Uric Acid - Cystine
50 Dog Charles Cavalier 11 year M + 2 1 6 1.022 Calcium Oxalate
51 Cat British 2 year M - 4 2 6 1.033 Calcium Oxalate - Uric Acid - Cystine
52 Cat Crossbreed 4 year M + 4 3 6 1.033 Calcium Oxalate - Calcium Sulfate
53 Cat Crossbreed 2 year M + 4 2 7 1.022 Calcium Oxalate - Uric Acid
54 Cat Scottish 2 year M + 1 1 7 1.022 Calcium Oxalate - Struvite
55 Cat Persian 2 year M + 0 2 8.5 1.011 Amorphous Biurate - Calcium Oxalate - Struvite
56 Cat Crossbreed 2 year M - 1 3 8 1.022 Calcium Oxalate
57 Cat Crossbreed 2 year M - 2 2 6.5 1.022 Calcium Oxalate - Cystine
58 Cat Crossbreed 3 year M - 2 3 8 1.022 Calcium Oxalate - Struvite – Calcium Phosphate
59 Cat Crossbreed 2 year M - 0 3 7 1.022 Amorphous Biurate - Calcium Oxalate
60 Cat British 4 year M - 3 3 8.5 1.011 Calcium Carbonate
61 Cat Persian 2 year M + 0 3 8 1.033 Calcium Oxalate - Struvite
62 Cat Crossbreed 2 year M + 0 2 7.5 1.022 Calcium Oxalate - Struvite – Calcium Phosphate
63 Cat Crossbreed 2 year M - 0 2 8 1.022 Calcium Oxalate - Struvite
64 Cat Crossbreed 3 year M - 1 0 6 1.022 Urate - Uric Acid
65 Cat Crossbreed 4 year F + 1 0 6 1.011 Uric Acid - Cystine - Calcium Oxalate
66 Cat Crossbreed 2 year M - 2 0 5.5 1.022 Uric Acid - Cystine
67 Dog Pomerian 4 year F + 0 0 7 1.022 Struvite
according to sex, neutered/castrated status and age of animals with
crystals in their urine are presented in the tables (TABLE II, III and IV).
It was determined that 74.57% of cats and 25% of dogs with crystals
detected in the urinary tract were crossbreeds. The distribution of the
animals with urine crystals according to breeds was presented in FIG 1.
In the study, 11 different crystal types were found in 67 animals
with crystals in their urine (FIGS. 2 and 3). While a single crystal
type was detected in the urine of 31 (46.27%) of these animals, it
TABLE II
Ratios of animals with urine crystals detected by sex
Sex
Dog Cat Total
n % n % n %
Female 3 37.5 8 13.56 11 16.42
Male 5 62.5 51 86.44 56 83.58
TABLE III
Ratios of animals with urine crystal detection according to neutering status
Neutering Status
Dog Cat Total
Female Male Female Male Female Male
n % n % n % n % n % n %
Neutered 2 66.67 2 4 5 62.5 23 45.10 7 63.64 25 44.64
Not neutered 1 33.33 3 60 3 37.5 28 54.90 4 36.36 31 55.36
Total 3 100 5 100 8 100 51 100 11 100 56 100
FIGURE 1. Distribution of cats (a) and dogs (b) with crystals in their
urine according to breeds
FIGURE 2. Phase microscope images of some urine crystals detected
in the study, Struvite (a), Calcium oxalate (b,c), Uric acid (d), Calcium
carbonate (e), Cystine (f), Calcium phosphate
FIGURE 3. Light microscope images of some urine crystals detected in
the study, Struvite (a, d), Calcium oxalate (b), Acyclovir (c), Amorphous
biurate (e), Cystine (f)
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was determined that there was more than one crystal type in the
urine of 36 (53.73%) animals. COC were found in 64.61% (n=38) of
the cats with crystals in their urine. SC were detected in 50% (n=4)
of the dogs. The detection rates of urine crystals in animals and
their distribution according to animal species were presented in
TABLE V. The distribution of the types of urine crystals by sex was
presented in TABLE VI.
In this study, it was determined that cats and dogs with crystals
in their urine were mostly cross-breeds. Histogram graphs showing
the distribution of urine crystals found in purebred breeds of cats
and dogs in the study are presented in FIG. 4.
TABLE IV
Ratios of animals with urine crystals detected by age ranges
Age
Dog Cat Total
n % n % n %
0–1 age 1 12.5 5 8.47 6 8.96
1–3 age 1 12.5 40 67.80 41 61.19
Over 3 years old 6 75 14 23.73 20 29.85
TABLE V
Detection rates of urine crystals in animals
and distribution by animal species
Crystal type
Cat Dog Total (Cat-Dog)
n % n % n %
Struvite 23 38.98 4 50.0 27 40.30
Calcium oxalate 38 64.41 2 25.0 40 59.70
Uric acid 13 22.03 - - 13 19.40
Cystine 8 13.56 1 12.50 9 13.43
Calcium phosphate 9 15.25 1 12.50 10 14.93
Amorphous biurate 5 8.47 - - 5 7.46
Urate 3 5.08 1 12.50 4 5.97
Calcium carbonate 3 5.08 - - 3 4.48
Hippuric acid 1 1.70 - - 1 1.49
Acyclovir 1 1.70 - - 1 1.49
Calcium sulfate 1 1.70 - - 1 1.49
FIGURE 4. Histogram graphs of the crystal types encountered in
purebred cat (a) and dog (b) breeds with crystals in the urinary tract
Urine Crystals in Cats and Dogs / Polat et al. ______________________________________________________________________________________
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Animals with crystals in their urinary tract; it was determined that
47.76% of them (n=32) were fed with home-made and unbranded
foods, 22.38% of them (n=15) were fed with foods containing 34-38%
crude protein, 20.90% of them (n=14) were fed with foods containing
40-44% of crude protein, and 8.96% of them (n=6) were fed with foods
containing 29-32% of crude protein. Cats with SC; it was determined
that 43.48% of them (n=10) were fed with home meals and unbranded
cat food, 34.78% of them (n=8) were fed with cat foods containing
36-42% crude protein, and 21.74% of them (n=5) were fed with cat
foods containing 29-32% of crude protein. It was determined that
all of the dogs with SC were fed with dog foods containing 42-44%
crude protein. Cats with COC; it was determined that 44.74% (n=17)
were fed with home meals and unbranded cat food, 31.58% (n=12)
with cat food containing 36-44% crude protein, and 23.68% (n=9)
with cat food containing 29-32% crude protein.
Urinary tract infections were found in 59.70% (n=40) of the animals
with crystals in the urinary tract. Urinary tract infections were found
in 70.37% of the animals (n=19) with SC. It was determined that this
rate was 73.91% in cats (n=17) and 50% in dogs (n=2). Urinary tract
infection was detected in 65.79% of the cats (n=25) in which COC
was detected. No urinary tract infection was detected in any of the
two dogs with COC.
Many physiological and pathological factors cause changes in
urine composition and cause the accumulation of crystals in the
urine (crystaluria). In patients who develop crystalluria, serious lower
US problems such as urolithiasis may develop in the future [1, 3, 16,
19, 20, 24, 25]. Some demographic factors such as animal species,
breed, age, and sex may have an effect on crystalluria/urolithiasis
formation and crystal type [3, 4, 16, 20, 24]. In this study, physical,
chemical and sediment examinations of the urine of animals with
suspected crystalluria/urolithiasis were performed. It was aimed to
determine the distribution of crystals according to types, the effect of
demographic factors on crystal formation, and the factors affecting
its etiology (such as nutrition, urinary tract infections) in 67 animals
(59 cats, 8 dogs) with crystals in the urinary tract during examinations.
Some studies [8, 21] have reported that dogs develop more
crystalluria urolithiasis than cats. Houston et al. [8], in their study
conducted at the Canadian Veterinary Urolith Center between 1998
and 2008, reported that 78% of the animals with uroliths were dogs.
Sancak et al. [21], reported that 11 of the 15 animals brought to Ankara
University Veterinary Faculty, between 2002-2003 and treated for
uroliths were dogs. In this study, contrary to similar ones, it was, it
was determined that more crystalluria/urolithiasis occurred in cats
(88.06%) than in dogs.
It has been reported that the incidence of crystalluria/urolithiasis
is higher in females in some studies [8, 12, 15, 24] and in males in
some studies [21]. In this study, it was determined that the incidence
of crystalluria was higher in males (83.58%). It was determined that
86.44% of cats and 62.5% of dogs with crystalluria were male. In
many studies [3, 8, 10, 12, 14, 15], it has been reported that SC are
more common in female cats and dogs, and COC are more common in
male cats and dogs. In this study, unlike other studies, SC were more
common in male cats than in female cats. However, it was determined
that the incidence of SC in dogs was higher in females than in males.
It was determined that the incidence of COC and other crystal types
was higher in both male cats and male dogs.
It is known that neutered/castrated has an effect on the formation
of some urine crystals [6, 12, 13]. Gisselman et al. [6], reported an
increased incidence of COC in neutered cats and dogs. Kopecny et
al. [12], in their study on 10,444 dogs, reported that 74.2% of male
dogs with COC and 84.3% of male dogs with UC were castrated. In this
study, it was determined that 63.64% of female cats and dogs with
crystalluria were neutered. It was determined that 44.64% of male
TABLE VI
The distribution of the types of urine crystals by sex
Crystal type
Female Male Total
n % n % n %
Struvite 5 18.52 22 81.48 27 100
Calcium oxalate 4 10.00 36 90.00 40 100
Uric acid 4 30.77 9 69.23 13 100
Cystine 2 22.22 7 78.78 9 100
Amorphous biurate 2 40.00 3 60.00 5 100
Calcium phosphate 2 20.00 8 80.00 10 100
Urate - - 4 100 4 100
Calcium carbonate - - 3 100 3 100
Hippuric acid - - 1 100 1 100
Acyclovir - - 1 100 1 100
Calcium sulfate - - 1 100 1 100
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cats and dogs with crystalluria had a castration operation. In addition,
the fact that 52.78% of male cats and dogs with COC were castrated
in this study is important in terms of supporting other studies.
One of the demographic factors affecting the formation of urine
crystals is age. SC mostly occur in young animals, while COC occur
mostly in older animals [3, 10, 12, 14, 16, 20]. Kopecny et al. [12], in
their study on 10,444 dogs, reported that the incidence of COC was
60% among dogs aged 7 years and older, and 57.6% of SC among dogs
younger than 7 AO. Langston et al. [14], on the other hand, reported
that the incidence of SC was higher in cats younger than four AO, and
COC were more common in cats older than seven AO. In this study, it
was determined that urine crystals were mostly seen in cats aged 1-3
(67.8%) and dogs older than 3 years (75%). In this study, similar to other
studies, it was determined that SC were mostly seen in young animals
(77.78% in animals three years and younger). However, contrary to
other studies, it was determined that COC were mostly seen in young
animals (70% in animals three years and younger).
There are many studies reporting that cats and dogs are predisposed
to breed in the formation of different urine crystals [1, 2, 6, 8, 15].
Houston et al. [8], in their study between 1998 and 2008, reported
that the risk of urolithiasis is high in dog breeds such as cross breeds,
Miniature schnauzer, Shih tzu, Lhasa apso, Bichon Frize and Yorkshire
Terrier. In cats, they reported that the risk of urolithiasis is high in
breeds such as domestic shorthair, domestic longhair, domestic
mediumhair, Himalayan, Persian, and Ragdoll. Albasan et al. [2],
reported that the risk of urolithiasis is high in cross breeds in cats and
Miniature schnauzer and Shih tzu breeds in dogs. In this study, urine
crystals were detected the most in cross breeds in both cats (74.57%)
and dogs (25%). Twenty ve percent of the of the urine crystals in
dogs were also detected in the Pomeranian breed.
Urine crystals can differ according to their chemical structure.
SC, COC, CC and UC are the most common urine crystals in pets
[24]. According to the Minnesota Urolith Center, the most common
urolite in dogs is SC, while in cats COC [3, 16, 20]. In the study of
Houston et al.[8], urolith cases detected in cats; it was determined
that 48.93% were COC and 43.30% were SC. In the same study, urolith
cases detected in dogs; it was determined that 45.24% had COC and
38.77% had SC. Albasan et al. [2] in their study, detected in cats urolith
cases; it was determined that 53.96% were COC and 41.06% were SC.
In this study, the cats with urine crystals detected; SC were detected
in 38.98% and COC in 64.41%. Of the dogs with urine crystals, SC were
detected in 50% and COC in 25%. Uric acid (22.03%), CC (13.56%) and
calcium phosphate (15.25%) crystals were detected in a signicant
portion of the cats with urine crystals.
Nutrition is a very important factor in the formation of crystalluria/
urolithiasis in cats and dogs. Commercial foods containing high
amounts of vegetables and grain feeds (high potassium cations) that
make the urine alkaline cause the formation of SC. In cats and dogs
fed with diets containing high amounts of animal protein, the acidity
of the urine increases due to protein catabolism. In this case, COC and
uroliths are formed [13]. In this study, it was determined that most of
the cats (65.22%) with SC were fed with low protein foods and home
meals. It was determined that dogs with SC were fed commercial
foods containing high protein but mainly vegetable protein. Again, in
this study, it was determined that only 31.58% of cats and dogs with
COC were fed commercial foods with high protein content.
It has been reported that the incidence of urinary tract infection
is high in animals with crystalluria/urolithiasis [3, 21]. In this study,
urinary tract infection was determined in 59.70% of the animals with
urinary crystals. While this rate was 65.79% in animals with COC, it
was 70.37% in animals with struvite crystals. In the study of Albasan
et al. [3], it was reported that 95% of dogs and 10% of cats with SC
were found to have urinary tract infections caused by proteus and
staphylococcus. In this study, urinary tract infections were detected
in 73.91% of cats and 50% of dogs with SC.
CONCLUSION
As a result, although the effect of demographic factors such as
species, breed, age and sex on the formation of urinary crystals was
similar in many studies, there were also differences. Urine crystals
were found to be higher in cats than in dogs, and in male animals than
in females. Urine crystals were found to be more common in cats
at young ages and in dogs at older ages. The most common urinary
crystal in cats was COC, while in dogs it was SC. It was determined
that sterilization signicantly increased the risk of urinary crystals
in female cats and dogs. However, it showed that neutering had no
signicant effect on the risk of urinary crystals in male cats and
dogs. In this study, it was determined that urine crystals were more
common in cats and dogs fed with poor quality and home food. In
addition, it was determined that urinary tract infection increased
the risk of urinary crystal formation.
Financial support
This research received no grant from any funding agency/sector.
Ethical statement
This study was approved by the Firat University Animal Experiments
Local Ethics Committee (20.01.2022, 2022/2, Document no: 6368).
Conict of interest
The authors declared that there is no conict of interest.
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