https://doi.org/10.52973/rcfcv-e34402
Received: 26/02/2024 Accepted: 20/05/2024 Published: 31/07/2024
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Revista Científica, FCV-LUZ / Vol. XXXIV, rcfcv-e34402
ABSTRACT
The objective of this study was to evaluate structural echotexture
changes in the uterine wall following abortion induction in bitches
during the late embryonic/mid–gestation stage and to develop an
evaluation method for the abortion process. A total of 10 healthy
pregnant bitches of different breeds, ranging from 25 to 40 days (d)
of gestation, were included in this study. In Group 1 (n=5), Aglepristone
(10 mg·kg
-1
bw, sc) was administered once daily for two consecutive
d. In Group 2 (n=5), a combination of Aglepristone, Cabergoline, and
Misoprostol was used for induction of abortion (IA). Prior to the
induction of abortion, and at 24–hour intervals until completion of
abortion (CA), the uterus and placenta were sonographically examined.
Additional examinations were conducted on d 1 (CA+1), d 7 (CA+7),
and d 14 (CA+14) after the abortion process was completed. Blood
samples were taken on the same days to detect serum progesterone
(P
4
) levels. Selected echotexture parameters (homogeneity, contrast,
gradient, and entropy) were assessed on sonographical images using
image analysis software (Bs200Pro®). Contrast and gradient values
signicantly decreased on d CA, CA+1 and CA+7 compared to the IA
state (P<0.05 and P<0.01). Contrast values were lower in G1 than G2 two
days before abortion (CA–2) (P<0.01). Gradient levels were higher in G2
than in G1 on CA–2 (P<0.01). Homogeneity values of G2 were higher than
in G1 on d CA–1 and CA+7 (P<0.05). Progesterone values showed a non–
signicant decrease after IA during the study period in both groups.
In G2, a negative correlation between P
4
and homogeneity (r=-0.797)
and a positive correlation between P
4
and contrast values (r=0.719)
were found. In conclusion, echotexture analysis allows quantitative
and objective evaluation of the uterine structure during abortion, but
specic standard values need to be established for both medication
protocols, taking into account individual factors.
Key words: Abortion; bitch; echotexture; uterus; placenta
RESUMEN
El objetivo de este estudio fue evaluar los cambios estructurales de
ecotextura en la pared uterina tras la inducción de un aborto en perras
durante la fase embrionaria tardía/media gestación y desarrollar un
método de evaluación del proceso abortivo. Se incluyeron en este
estudio un total de 10 perras gestantes sanas de diferentes razas, con
edades comprendidas entre los 25 y los 40 días (d) de gestación. En
el Grupo 1 (n=5), se administró Aglepristona (10 mg·kg
-1
de peso vivo,
vía oral) una vez al día durante dos días consecutivos. En el Grupo2
(n=5), se utilizó una combinación de Aglepristona, Cabergolina y
Misoprostol para la inducción del aborto (IA). Antes de la inducción
del aborto, y a intervalos de 24 horas hasta la nalización del aborto
(AC), se examinaron ecográficamente el útero y la placenta. Se
realizaron exámenes adicionales el d 1 (AC+1), el d 7 (AC+7) y el d 14
(AC+14) tras la nalización del proceso de aborto. Los mismos días
se tomaron muestras de sangre para detectar los niveles séricos
de progesterona (P
4
). Se evaluaron determinados parámetros de
ecotextura (homogeneidad, contraste, gradiente y entropía) en las
imágenes ecográcas utilizando un software de análisis de imágenes
(Bs200Pro®). Los valores de contraste y gradiente disminuyeron
signicativamente en los d CA, CA+1 y CA+7 en comparación con el
estado IA (P<0,05 y P<0,01). Los valores de contraste fueron inferiores
en G1 que en G2 dos días antes del aborto (CA–2) (P<0,01). Los niveles de
gradiente fueron mayores en G2 que en G1 en CA–2 (P<0,01). Los valores
de homogeneidad de G2 fueron superiores a los de G1 en los días CA–1 y
CA+7 (P<0,05). Los valores de P
4
mostraron un descenso no signicativo
tras la IA durante el periodo de estudio en ambos grupos. En G2, se
encontró una correlación negativa entre P
4
y homogeneidad (r=-0,797)
y una correlación positiva entre P
4
y valores de contraste (r=0,719).
En conclusión, el análisis de ecotextura permite una evaluación
cuantitativa y objetiva de la estructura uterina durante el aborto, pero
es necesario establecer valores estándar especícos para ambos
protocolos de medicación, teniendo en cuenta los factores individuales.
Palabras clave: Aborto; perra, ecotextura; útero; placenta
Evaluation of the uterine wall echotexture changes following an induced
abortion in mid–term pregnant bitches: preliminary study
Evaluación de los cambios de ecotextura de la pared uterina tras un aborto
inducido en perras gestantes a medio plazo: un estudio preliminar
Yelda Bal
1
, Erol Alaçam
2
, Selim Aslan
3
, Duygu Kaya
4
* , Serkan Barış Mülazimoğlu
5
, Serhan Serhat Ay
6
, Sabine Schäfer–Somi
7
1
Baskent Animal Hospital. Ankara, Türkiye.
2
Ankara University, Department of Obstetrics and Gynecology. Ankara, Türkiye.
3
Near East University, Veterinary Faculty, Department of Obstetrics and Gynecology. Nicosia, Turkish Republic of Northern Cyprus.
4
Dokuz Eylül University, Faculty of Veterinary Medicine, Department of Obstetrics and Gynaecology. İzmir, Türkiye.
5
Hacettepe University, Technopolis–Hemosoft IT and Training Services Inc. Ankara, Türkiye.
6
Ondokuz Mayıs University, Faculty of Veterinary Medicine Department of Obstetrics and Gynaecology. Samsun, Türkiye.
7
University of Veterinary Medicine, Centre for Articial Insemination and Embryo Transfer. Vienna, Austria.
*Corresponding Author: dygkaya@gmail.com
Evaluation of the uterine wall echotexture changes in bitches / Bal et al. ___________________________________________________________
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INTRODUCTION
The increasing surge in the population of stray animals presents a
signicant global concern with profound implications for both public
health and the well–being of animals. The prevailing approach to tackle
this issue revolves around reproductive control. Within the domain
of veterinary medicine, procedures for reproductive control are not
only legally endorsed but also routinely implemented, even during
different stages of pregnancy [1].
In bitches (Canis lupus familiaris), unwanted mating is a common
concern for pet owners due to the delicate care required for the
pregnant bitch and the puppies after delivery [1, 2]. Several termination
protocols have been introduced in the eld of canine reproduction,
some demonstrating hormonal changes, while others have investigated
clinical ndings after the induction of abortion. Anti–progestins, such
as Aglepristone, are often used for pregnancy termination in bitches
after mismating [3, 4]. Aglepristone, a progesterone (P
4
) receptor
blocker, exhibits greater anity to progesterone receptors than natural
progesterone and is the most frequently used anti–progestin for inducing
abortion without a decrease in plasma P
4
concentrations. It is injected
subcutaneously on two consecutive days for abortion induction [3, 5, 6].
The dopamine agonist Cabergoline has also been used for pregnancy
termination in bitches [7, 8]. This agonist decreases prolactin
secretion, leading to a decrease in P
4
levels, as Prolactin is a luteotropic
agent in bitches [9, 10]. Misoprostol, a synthetic prostaglandin E
1
analogue which causes cervical dilatation, myometrial contractions,
vomiting, diarrhea, among other effects, is used for the induction
of abortion and labor, as well as the treatment of postpartum
hemorrhage in women [11, 12] and induction of abortion in bitches
[8, 13]. Combinations of these agents are often used to accelerate
the abortion process [10, 13]. Agaoglu etal. [13] reported that the
use of a combination of Aglepristone and Misoprostol resulted in
faster cervical dilation, with all the animals in this group successfully
completing the abortion procedure. However, in the other groups,
abortion was not completed by the 6
th
day after treatment. In another
study, pregnancies in bitches were terminated more quickly with a
combination of Aglepristone and Cabergoline than with Aglepristone
alone (6.8 versus 10.6 d) [10].
Examination of the reproductive tract in bitches is usually
performed by ultrasonography. Different sonographical methods
were proven useful for the evaluation of cyclic changes of the ovary,
monitoring of pregnancy, embryonic death and the puerperium [14,
15]. Puerperium denes the period after the expulsion of the last
fetus and placenta, and includes the involution and endometrial
regeneration for normal return to cyclicity [16, 17]. In human medicine,
high–frequency color Doppler ultrasonography allows the evaluation
of uteroplacental circulation in early pregnancy. Pregnancy–related
abnormalities have been associated with pregnancy complications
such as hypertension, intrauterine growth restriction (IUGR), fetal
distress, and early pregnancy failure [18, 19, 20]. The ability of Doppler
sonography to analyze the circulation pattern even in the terminal
branches of the uteroplacental circulation stimulates research for
its potential application in examination of early and late gestational
periods, in both human and veterinary medicine; the combination
with echotexture analysis might be useful.
Computer–assisted echotexture analysis programs were introduced
many years ago for purposes such as differentiation of breast tumors
from healthy tissues in human medicine [21, 22] as well as recognizing
and treating placental disturbances during pregnancy in a timely
manner [23]. Echotexture analysis enables quantitative and objective
assessment of the examined tissues [24, 25]. This technique is based
on the mathematical relations of the pixels in ultrasonographic
images, which are represented numerically (0–255), in the shades
of gray, according to their brightness intensity [25, 26]. In veterinary
reproduction, echotexture analysis programs are used for determining
cyclic changes of the endometrium [27] and corpus luteum [26] and
endometrial changes after treatment of endometritis [28] in cows.
Computer–assisted image analysis was used for the assessment of
postpartum endometrial echotexture changes in cows instead of
the subjective evaluation of the real time ultrasound images [28,
29]. Furthermore, it was used for the evaluation of the endometrial
changes in echotexture parameters in cyclic and early pregnant
goats [30]. Mülazimoğlu et al. [31] reported signicant differences
between malignant and benign canine mammary tumors in terms
of echotexture parameters, and the analysis system was used for
assessment of ovarian echotexture changes in bitches [32].
According to literature knowledge, echotexture analysis has not
yet been utilized for monitoring the abortion process previously.
The hypothesis of this study suggests that echotexture analysis of
the uterus during abortion in bitches might reveal characteristic
changes in the endometrium throughout the abortion course. This
could aid in recognizing abnormalities from the normal abortion
process, potentially enabling early intervention.
The objective of this study was to assess the feasibility of utilizing
echotexture analysis for monitoring both the abortion process and the
subsequent involution period post–abortion. To achieve this objective,
changes in certain echotexture parameters were examined following
induction of abortion in mid–term pregnant dogs using two different
treatment protocols. The hypothesis postulated that variations in
uterine structure during the abortion process would exhibit disparities
between the two medication protocols. The hypothesis was that the
change in uterine structure during the abortion process would differ
between the two medication protocols.
MATERIALS AND METHODS
Animals and treatments
A total of 10 healthy pregnant bitches from different breeds, aged
1 to 5 years, with a body weight ranging from 12 to 34 kg, and at 25 to
40 days (d) of gestation were included in this study with the written
consent of their owners. All animals had a history of unwanted
pregnancy. The animals were assigned randomly into two groups.
Two bitches on the 40
th
d of pregnancy were randomly assigned to
both groups to ensure homogeneity. The remaining bitches were less
than 35 d of gestation. The pregnant bitches were adopted from an
animal shelter by the owners, under the condition that the bitches
would undergo ovariohysterectomy afterward.
Since post–abortion surgery is less risky for the bitch, abortion was
induced in all animals. In Group 1 (G1, n=5) Aglepristone (Alizin®, Virbac
Animal Health, New Zealand, 10 mg·kg
-1
, SC) was administered once
daily on two consecutive days. In Group 2 (G2, n=5) a combination of
Aglepristone, Cabergoline (Galastop®, Ceva Sante Animale, Libourne,
France, 5 μg·kg
-1
PO) and, Misoprostol (Cytotec®, Ali Raif Ilaç Sanayi,
Istanbul, Türkiye, 200 μg for bitches with less than 20 kg bw, 400 μg
for bitches with greather than 20 kg bw, intravaginally), was used
for induction of abortion (IA). Aglepristone was administrated as
in G1, while Cabergoline and Misoprostol were administrated daily
FIGURE 1. A representative ultrasound image with dened regions of interest
(ROIs) for echotexture analysis. Figure captions: At day 35 of gestation, the
ultrasound image depicts the uterus and fetus during abortion. Four regions
of interest (ROIs) are positioned in the uterine wall and placenta, both in the
upper and lower regions of the uterus
_____________________________________________________________________________Revista Cientifica, FCV-LUZ / Vol. XXXIV, rcfcv-e34402
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until completion of abortion. The animals were hospitalized until the
abortion process was completed. Animal experiments were conducted
under a protocol approved by the Animal Experiments Local Ethics
Committee of Ankara University (No: 2009–50–247).
Examinations, sampling and hormonal analyses
Pregnancy was determined by trans–abdominal ultrasonography
(USG) (Falco Vet 100, 6–8 MHz linear array transducer, (PieMedical,
Imaging BV, Maastricht, The Netherlands). The image settings
(brightness and contrast) of the ultrasonography apparature, the probe
angle in image acquisition, the distance of the probe to the target
tissue (tissue depth), and the positions of the dogs (supine position)
were uniform. Determination of the gestational age was performed by
the measurement of fetal and extrafetal structures reported by Luvoni
and Grioni [33] and Yeager et al. [34] For this purpose, crown–rump
length (CRL), extrafetal structures (ICC: inner chorionic cavity, OUD:
outer uterine diameter) and biparietal diameter were measured during
ultrasonographic examinations. Abortion process and the following
period (d1, d7 and d14) were monitored by daily inspection of the vaginal
discharge, vaginoscopy and ultrasound examinations. Determination
of cervical dilatation and uterine discharge during vaginoscopic
examination was considered as start of abortion (SA) and absence of
any fetus/fetal structures during USG examination was also considered
as the completion of abortion process (CA). After determination of the
d of CA, two (CA–2) and one d (CA–1) before abortion were determined
retrospectively. The period between start of treatment (pregnancy
diagnosis, induction of abortion=IA) and CA was recorded. All bitches
were hospitalized until CA, received commercial dry dog food twice a
day and water ad libitum.
Blood sampling started just before the induction of abortion and was
performed daily until CA and also on d 1 (CA+1), 7 (CA+7) and 14 (CA+14)
after abortion in all animals. Samples were centrifuged at 1100 G force for
15 min (Heraeus Labofuge GL®, Germany) and stored at -20°C (Arçelik®
4253, Türkiye) until hormonal analysis. Serum P
4
concentrations were
measured by using radioimmunoassay (RIA) kit (Immunotech, Prague,
Czech Republic). An automatic open analyzer system (Stratec SR 300,
Birkenfeld, Germany) was used to detect radioactivity following the
manufacturer’s protocol. Results are given in ng·mL
-1
.
Acquisition and evaluation of ultrasonographic images
All groups of bitches underwent sonographic examinations on the
same d as blood collection. Ultrasound examinations captured BMP–
formatted images of the uterine wall and fetuses, which were then saved
in PNG format and assigned to their respective groups. To minimize
artifacts and identify images best representing the physiological
and pathological conditions, 3 to 10 images were recorded during
each ultrasonography examination. The image that most accurately
represented the specic period was selected for subsequent analysis.
Recorded ultrasonographic images were imported into the image
processing software (Bs200Pro
®
, BAB Digital Imaging System, Ankara,
Türkiye). Regions of interest (ROI) were dened according to established
methods in the literature [1, 9, 35]. Four regions of interest (ROI) with
10 pixels per site (100 square pixel) were selected for both the uterine
wall and placenta in each ultrasonographic image by the software (FIG.
1). Within these ROIs, echotexture parameters (homogeneity, contrast,
gradient, and entropy) were assessed using a pixel–based color analysis
system and were automatically calculated by the software. For a
detailed description of the echotexture parameters, refer to Zabitler
et al. [35] Utilizing the database transfer module of the software, the
data was regularly transferred to MS Excel® software. Eight images
were captured and saved for each parameter (5×8=40), and in each
image, four ROIs were examined (40×4=160 ROIs).
Statistical analyses
Statistical calculations were conducted using SPSS
®
software
(Version 14.0 for Windows, Chicago, IL, USA). The normality of
distributions was assessed through Marginal Homogeneity and
Kolmogorov–Smirnov Z Tests. To determine differences between values
before and after treatment, the Wilcoxon Test was employed. Group
comparisons were made using the Mann–Whitney U test. Results are
expressed as mean ± standard deviation (x̄ ± SD). A P–value of less than
0.05 was considered statistically signicant
RESULTS AND DISCUSSION
Aglepristone is the most preferred medical agent for termination
of pregnancy in the bitch [3, 4, 10, 36]. Combinations of Aglepristone
with Cabergoline, misoprostol or PGF2α have been used to shorten
the abortion period [1, 13, 37]. In this study, the aim was to evaluate
the changes in echotexture parameters rather than the effects of
the treatments on abortion process when Aglepristone was used
alone or in combination with Cabergoline and Misoprostol. For this
purpose, echotexture parameters; gradient, entropy, homogeneity
and contrast were observed during and after the abortion process.
This study encountered a signicant limitation due to the restricted
number of animals included. The utilization of data from animals at
various stages of pregnancy (d 25–40) has constrained the assessment
of results based on specic pregnancy periods. While a substantial
portion of the study focused on animals in the rst half of pregnancy
(less than 35
th
d), the small sample size prevented the evaluation of
values from two 40–d pregnant dogs in a separate group. Therefore,
there is a pressing need for more comprehensive prospective studies,
involving a larger cohort of animals, to gain a deeper understanding
of the biological signicance inherent in these results.
TABLE I
Completed abortions during the time period after induction
Groups
Distribution of completion rates of abortions by days
Day 3 Day 4 Day 5 Day 6 Day 7
G1 20% (1/5) 60% (3/5) 60% (3/5) 100%
a
(5/5) –
G2 0 % 0 % 40% (2/5) 40%
b
(2/5) 100% (5/5)
Values within a row with dierent superscripts dier significantly (
a,b
P<0.05). G1 (n=5):
Aglepristone only. G2 (n=5): Aglepristone, Cabergoline and Misoprostol
TABLE II
Echotexture parameters of the uterine wall before and after the abortion process in all animals
Echotexture Parameters
Induction of
abortion
Days before
abortion
Completion
of abortion
Days after
abortion
IA CA – 2 CA – 1 CA CA + 1 CA + 7 CA + 14
Gradient (n=40) 13.7 ± 0.6
a
13.2 ± 0.5 12.4 ± 0.5 12.2 ± 0.7
b**
12.0 ± 0.4
b**
11.7 ± 0.5
b**
15.4 ± 1.0
Homogeneity (n=40) 5.8 ± 0.3 5.4 ± 0.2 6.2 ± 0.3 6.5 ± 0.3 5,9 ± 0,3 6.1 ± 0.3 4.8 ± 0.3
Entropy (n=40) 1.0 ± 0.0 1.0 ± 0.0 1.0 ± 0.0 1.0 ± 0.0 1.0 ± 0.0 1.04 ± 0.0 1.0 ± 0.0
Contrast (n=40) 44.9 ± 4.8
a
37.9 ± 4.1 36.1 ± 3.9 38.6 ± 6.5
b*
32.4 ± 2.6
b**
31.5 ± 3.1
b**
76.8 ± 16.4
IA: Induction of abortion, CA: End of abortion. CA1/CA2: One/two days before the abortion; CA+1, CA+7, CA+14: 1, 7 and 14 days after abortion; Values
within a line with dierent superscripts dier significantly (
a,b*
P<0.05,
a,b**
P<0.01)
Evaluation of the uterine wall echotexture changes in bitches / Bal et al. ___________________________________________________________
4 of 8
There was no difference between the days of pregnancy in the
groups (G1: 32.0 ± 6.2 and G2: 34.6 ± 3.6 d, P>0.05).
A brownish vaginal discharge was observed during vaginoscopy at
the onset of abortion, while a hemorrhagic/pinky discharge was noted
after the completion of abortion. The abortion process was completed
in 4.2 ± 0.5 d in G1 and 5.8 ± 0.4 d in G2 (P>0.05). Inductions of abortion
were successful in 100% of cases (n=10). In G1, all bitches completed
abortion on d 6, while in G2, only 40% of bitches achieved abortion by
the same d (P<0.05). The remaining bitches in G2 underwent abortion
on d 7 (TABLE I).
whereas a negative correlation between P
4
and homogeneity (r=-0.797,
P<0.05) and a positive correlation between P
4
and contrast values
(r=0.719, P<0.05) were observed in G2.
When the data of all dogs in both groups were evaluated from
induction to the 14
th
d after completion of abortion, significant
changes were observed only in gradient and contrast values. Both
parameters exhibited a signicant decrease (P<0.05 and P<0.01) on
the d of abortion (CA) as well as on the 1
st
(CA+1) and 7
th
(CA+7) d after
abortion, compared to the d of induction of abortion (IA) (TABLE II).
This study provides preliminary results of the changes in the
echotexture of the uterus before, during and after the abortion in
bitches; no comparable study was found in the literature. So far,
these results can only be compared to those obtained with similar
methods, materials and settings during normal canine pregnancy; a
previous study provided rst results Zabitler et al [35]. Unfortunately,
comparisons between studies are only possible, when the settings are
standardized; this includes the sonographic evaluation and the analysis
of the image. This results therefore must be considered as preliminary
data and await conrmation by further examinations and other groups.
There are studies showing that uterine echotexture parameters
(gradient, homogeneity, contrast) change dependent on pregnancy
stage and cycle stage, also dependent on steroid hormone
concentrations; the P
4
level or the estrogen–progesterone ratio
[27, 30, 35, 41].
In the presented study, no relation was found between
the echotexture parameters and P
4
values in G1; however, a negative
correlation between P
4
and homogeneity (r=–0.797) and a positive
correlation between P
4
and contrast values (r=0.719) were calculated
in G2 comparable to previous studies. The latter might be explainable
by a quicker change in uterine structures during the ongoing abortion.
Homogeneity was higher after completion of abortion than before
the initiation of abortion, probably due to a quick maceration and
ongoing resorption of tissues and uids during and after the abortion.
Together with the markedly decreased P
4
concentrations, the negative
correlation can be explained. However, the course of progesterone is
not believed to be causative for the differences in uterine structure.
In both G1 and G2, there was no signicant difference in gradient
values across the days based on the applications. However, in both
groups, gradient values exhibited a signicant decrease (P<0.01,
P<0.05) at the d of abortion (CA) and on the seventh d after abortion
(CA+7) compared to the d of abortion induction (TABLE III). The
mean gradient levels were higher in G2 (14.7) than in G1 (11.3) two d
before abortion (CA–2) (P<0.01); conversely, these levels were higher
(P<0.01) in G1 on d 14 after abortion (CA+14). No signicant difference
was found on the d of abortion completion between the two groups
In this study, abortion was completed in 4.2 d in G1 and 5.8 d in G2,
with placental separation and fetus expulsion occurring slightly faster
in G1 than in G2. Previous research has suggested that combining
Aglepristone with Misoprostol or Cabergoline induces abortion earlier
than Aglepristone alone [13]. Similarly, the study conducted in cats
indicated that the combination with MIS (AGL+MIS) can achieve better
results than the use of AGL alone [38]. This effect is likely due to
additive effects, as observed in the bitch, where the acceleration
of cervical dilatation after the combined use of AGL and MIS. This is
supported by MIS causing long–term and intense uterine contractions
[39, 40]. In this study, the combination with Misoprostol did not
signicantly accelerate abortion. The main nding is that abortion
can be completed with Aglepristone alone in a relatively short time,
and the additional use of Cabergoline and Misoprostol may not be
necessary, at least not with the medication protocol used here.
Due to the use of different treatment methods in the groups, a mild
decrease in P
4
was observed in G1, while it was more pronounced but
non–signicant in G2. In G2, a decrease in P
4
levels was observed from
24.73 ng·mL
-1
on d IA to 5.35 ng·mL
-1
on d CA–2. In G1, the respective
values were 13.48 ng·mL
-1
and 13.42 on d IA and CA–2. No correlation
was found between the echotexture parameters and P
4
values in G1,
TABLE III
Changes in the echotexture parameters between two treatment groups
Parameter A (n=20)
Induction of
abortion
Days before
abortion
Completion
of abortion
Days after
abortion
P
CA – 2 (n=20) CA – 1 (n=20) CA (n=20) CA CA+1 (n=20) CA+7 (n=20) CA+14 (n=20)
Gradient
G1 14.4 ± 1.0
a* #
11.3 ± 0.4 (n=16) 13.2 ± 0.6 12.6 ± 1.1
b*
12.4 ± 0.6 12.2 ± 0.6
b* #
17.1 ± 1.6
a,b*
<0.05
G2 13.1 ± 0.8
a ¥
14.7± 0.8 11.6 ± 0.8 11.8 ± 0.9
b*
11.6 ± 0.5 11.2 ± 0.7
b** ¥
12.8 ± 0.7 (n=12)
a,b*
<0.05
a,b**
<0.01
P >0.05 <0.01 >0.05 >0.05 >0.05 >0.05 <0.05
Entropy
G 1 1.0 ± 0.0
a
1.0 ± 0.0
a
(n=16) 1.0 ± 0.0
a
1.0 ± 0.0
a
1.0 ± 0.0
a #
1.0 ± 0.0
a
1.0 ± 0.0
a a
>0.05
G 2 1.0 ± 0.0
a
1.0 ± 0.0
a
1.0 ± 0.0
a
1.0 ± 0.0
a
1.0 ± 0.0
a ¥
1.0 ± 0.0
a
1.0 ± 0.0
a
(n=12)
a
>0.05
P >0.05 >0.05 >0.05 >0.05 >0.05 <0.05 >0.05
Homogeneity
G 1 6.2 ± 0.6
a
5.9 ± 0.3 (n=16)
#
5.5 ± 0.4 6.4 ± 0.4 5.4 ± 0.4 #5.3 ± 0.4 4.7 ± 0.5
b* a,b*
<0.05
G 2 5.4 ± 0.4
a
4.9 ± 0.4
¥
6.8 ± 0.5 6.5 ± 0.6
b*
6.5 ± 0.5
¥
6.8 ± 0.5
b*
5.0 ± 0.4 (n=12)
a,b*
<0.05
P >0.05 >0.05 <0.05 >0.05 >0.05 <0.05 >0.05
Contrast
G 1 49.6 ± 7.4
a #
24.9 ± 1.6 (n=16) 38.9 ± 3.6 44.2 ± 10.5 36.4± 4.2
b*
32.2 ± 3.6
b* #
32.4 ± 5.4
a,b*
<0.05
G2 40.3 ± 6.2
a ¥
48.3 ± 6.7 33.4± 7.1 33.1 ± 7.8
b*
28.4± 2.9 30.7 ± 5.1
¥
42.7 ± 10.4 (n=12)
a,b*
<0.05
P >0.05 <0.01 >0.05 >0.05 >0.05 >0.05 <0.05
IA: Induction of abortion, CA: End of abortion. CA1/CA2: One/two days before abortion; CA+1, CA+7, CA+14: 1, 7 and 14 days after abortion. G1 (n=5): Aglepristone only. G2 (n=5):
Aglepristone, Cabergoline and Misoprostol. Statistical dierence between rows is shown by letters (
a,b
), statistical dierence between columns by asterisks (
#,¥
). Values shown
with dierent letters / asterisks are significantly dierent from each other (
P<0.01; P<0.05)
_____________________________________________________________________________Revista Cientifica, FCV-LUZ / Vol. XXXIV, rcfcv-e34402
5 of 8
(P>0.05). However, it was observed that in both groups on the day of
CA, the mean gradient value decreased, and the mean contrast value
increased compared to the d of IA (TABLE III). In pregnant bitches,
depending on pregnancy stage and reproductive hormones, many
structural changes occur due to a change in uterine blood ow,
proliferation and secretion of endometrial glands, and an increase
in tissue thickness, tissue edema and placenta formation [35].
After parturition or during abortion, the situation changes which is
mirrored in the changings of contrast and gradient in the present
study; however, to a highly differing degree and this is believed to
be due to the different medication protocols.
Gradient is a measure of the differences in grey structures [42]
and
when there is no difference in grey value between pixels, the average
gradient value is zero, indicating a perfectly homogeneous image.
Contrast, on the other hand, is employed to determine the intensity
variations of different grey values within the selected region of
interest (ROI) [43]. In this study, signicant decreases were observed
in gradient and contrast values on days CA, CA+1, and CA+7 (P<0.01),
which could be associated with the reduction in the diameters of the
endometrial glands and the removal of abortion material during the
involution procedure of the uterus, particularly in the rst 14 d of the
puerperal period. The increasing values on day CA+14 might reect
the regeneration of the endometrium. These results suggest that
uterine changes during abortion could be identied by alterations
in gradient and contrast, providing valuable insights for monitoring
abortion; however, variations exist based on the medication scheme,
with the disparity likely attributable to the use of Misoprostol.
Contrast values of G1 signicantly decreased between the day of IA,
CA+1 and CA+7 (P<0.05). In G2, a signicant decrease was observed
only between the day of IA and CA (P<0.05). Gradient and contrast
values were signicantly lower in G1 compared to G2 on the day of
CA–2 (P<0.01) and on the day of CA + 14 (P<0.05) (TABLE III)
Treatment with PGE1 not only signicantly increased myometrial
contractions but also decreased total collagen content and connective
tissue amount, possibly linked to increased collagenase activity.
Consequently, mean gradient and contrast levels were higher in G2
than in G1 two days before abortion (CA–2) (P<0.01). Similarly, observed
homogeneity differences between the two groups may also be
attributed to uterine contractions and endometrial bleeding induced
by Misoprostol. Homogeneity and gradient levels exhibit contrasting
behaviors [27] and higher homogeneity values indicate more uniform
gradient combinations [24], as also observed in this study.
In both the rst and second groups, there was no signicant change
in entropy values in the post–application period and the post–abortion
period (P>0.05). However, a signicant difference (P<0.05) between
the two groups was observed only on the d of CA+7 (TABLE III).
In the rst group, homogeneity values signicantly decreased
between the d of IA and d CA+14 (P<0.05). In contrast, in G2,
signicantly higher values were obtained on d CA and CA + 7 compared
to the d of IA (P<0.05). Furthermore, homogeneity values of G2 were
higher than G1 on d CA–1 and CA+7 (P<0.05; TABLE III).
Misoprostol, a Prostaglandin E1 analog, induces cervical dilatation
and uterine contractions. Cervical dilation involves complex molecular
factors [44] and collagen molecule rearrangement, reduced collagen
bers, and increased elasticity contribute to the opening process
[45, 46]. Misoprostol administration may alter endometrial tissue
thickness [47], induce severe uterine contractions, and cause
endometrial bleeding [48]. In the presented study, G2, where
Misoprostol was administered, experienced more vigorous uterine
contractions, likely contributing to differences compared to G1 during
uterine involution after abortion. The observed differences in uterine
echotexture between the two groups are likely primarily due to these
effects of Misoprostol.
After abortion and during uterine involution, the diameter of the
uterine horns and blood ow to the uterus decrease, inuenced by
the type of delivery in the bitch [49] and the course of abortion, as
demonstrated in this study. Signicant differences between groups,
Evaluation of the uterine wall echotexture changes in bitches / Bal et al. ___________________________________________________________
6 of 8
especially in contrast and gradient values on day CA–2 and CA+14
compared with IA, indicate distinct effects of the two treatments on
endometrial and uterine changes before abortion and during involution.
Changes in echotexture parameters during involution are, among other
factors, a result of regeneration in the endometrium, as observed in
the regeneration after the treatment of endometritis in cows [28].
CONCLUSIONS
Echotexture analysis allows quantitative and objective evaluation
of the examined tissues. Abortion performed after implantation and
mid–pregnancy causes characteristic tissue echotexture, and different
drugs used to induce abortion can lead to different changes in tissue
echotexture. Monitoring the change in the uterine structure during
abortion is promising, but specic standard values need to be established
for both medication protocols, taking into account individual factors.
Conict of interest
The authors declared no potential conicts of interest with respect
to the research, authorship, and/or publication of this article.
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