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Brazilian Journal of Veterinary Pathology. www.bjvp.org.br . All rights reserved 2007-2021.
Santana and Santos.; Canine pyometra – an update and revision of diagnostic terminology
Braz J Vet Pathol, 2021, 14(1), 1 – 8
DOI: 10.24070/bjvp.1983-0246.v14i1p1-8
1
Literature Review
Canine pyometra – an update and
revision of diagnostic terminology
Clarissa Helena Santana1, Renato Lima Santos1*.
1 Departamento de Clínica e Cirurgia Veterinárias, Escola de Veterinária, Universidade Federal de Minas Gerais.
Av. Antonio Carlos, 6627 - 31270-901 Belo Horizonte, MG, Brazil.
*Corresponding author: RLS. Departamento de Clínica e Cirurgia Veterinária, Escola de Veterinária, Universidade Federal de Minas Gerais,
Av. Presidente Antônio Carlos, 6627 – CEP 30161-970, Belo Horizonte, MG, Brazil. Phone: 55-31-3409-2239. Fax: 55-31-3409-2230.
E-mail: rsantos@vet.ufmg.br
Submitted December, 17th 2020, Accepted February, 6th 2021
Abstract
Pyometra is frequently diagnosed in female dogs, and it is characterized by endometrial inammation, accumulation
of purulent exudate within the lumen, and bacterial infection. In the dog, pyometra affects more often aged nulliparous
bitches during the luteal phase. Pathogenesis of pyometra is multifactorial and progesterone seems to be a key factor. Cystic
endometrial hyperplasia has been described as a predisposing condition for canine pyometra. However, a recent study
demonstrated that cystic endometrial hyperplasia is not signicantly associated with naturally occurring pyometra, whereas
there is a signicant association of this condition with pseudoplacentational endometrial hyperplasia. The aim of this review
is to provide an update on canine pyometra, with focus on its association with uterine hyperplasic lesions, which supports a
proposal for adoption of more adequate diagnostic terminology.
Key words: female dog; endometritis; pseudoplacentational endometrial hyperplasia; reproductive pathology.
Introduction
Pyometra is a condition characterized by uterine
inammation with accumulation of purulent exudate within
the uterine lumen, associated with bacterial infection that
results in systemic illness (12, 24). Pyometra may affect
several animal species (1-4, 25, 30, 33, 36, 37). In female
dogs, pyometra is a life-threatening disease that affects,
more frequently, old nulliparous bitches, during the luteal
phase when there are higher of progesterone plasmatic
levels (12, 38).
The pathogenesis of pyometra in female dogs is
complex, and it is affected by several factors including
bacterial infection, neutrophilic activity, uterine motility,
and concentration of immunoglobulins (42). Although the
pathogenesis of pyometra is not completely understood, it
is accepted that pyometra is a disease of the diestrus, and
that high progesterone levels are critical for development of
infection (8, 12, 43).
Early studies suggested an association of pyometra
and cystic endometrial hyperplasia (CEH) so the condition
was named “CEH – pyometra complex” (12). However, the
concept of “CEH - pyometra complex” has been currently
questioned. There is no clear demonstration of a cause and
effect relationship between these two pathologic changes,
which are both associated with diestrus, and both affects
aged bitches. Additionally, the severity of the clinical
signs in bitches with pyometra does not correlate with
the currently used histological classication (8), which
undermines the communication between pathologists and
clinicians. Importantly, another common hyperplastic
condition that affects the canine endometrium, namely
pseudoplacentational endometrial hyperplasia (PEH), has
been recently characterized as an endometrial change that
also commonly develops during the diestrus (43).
A recent study demonstrated that there is no
signicant association between CEH and naturally occurring
pyometra (39). These ndings are in sharp contrast with the
Brazilian Journal of Veterinary Pathology. www.bjvp.org.br . All rights reserved 2007-2021.
Santana and Santos.; Canine pyometra – an update and revision of diagnostic terminology
Braz J Vet Pathol, 2021, 14(1), 1 – 8
DOI: 10.24070/bjvp.1983-0246.v14i1p1-8
2
classical concept that there is a cause and effect relationship
between these uterine lesions in bitches (12). Interestingly,
a signicant association and positive correlation between
PEH and pyometra was demonstrated (39). These ndings
prompted us to revise the concept of “CEH - pyometra
complex”.
The aim of this review is to provide an update
on canine pyometra, with emphasis on the association of
pyometra with hyperplastic endometrial changes, which
supports a proposal for adoption of more adequate diagnostic
terminology.
Clinical and epidemiologic aspects of canine pyometra
Pyometra is a uterine pathologic change that
is commonly diagnosed in intact female dogs. Usually,
pyometra affects middle-aged to old female dogs, with
median age ranging from 6.50 to 9.36 years (12-14, 17,
27). Some studies demonstrated breed predisposition,
with higher incidence in Bernese Mountain Dog, Collie,
Rottweiler, Cavalier King Charles Spaniel, Golden
Retriever, Bullmastiff, and Dogue de Bordeaux (13, 17, 27).
These ndings suggest that genetic factors may predispose
or prevent the development of the disease (13, 17, 27).
Studies carried out in Sweden, involving
approximately 200,000 bitches, demonstrated an incidence
of pyometra of 2.10% and 1.99% (13, 27). Another
study including 165 colony-raised Beagle dogs in Japan,
demonstrated an incidence of pyometra of 15.2% (14). In a
retrospective study in ve hospitals in the United Kingdom,
from 2006 to 2011, involving 78,469 dogs, the prevalence
of pyometra was 2.2% and the incidences were 1.8% and
2.9%, in 2006 and 2011, respectively (17).
Clinically, uterine uid accumulation and
enlargement of the uterus may be due to mucometra,
hydrometra or pyometra. Mucometra and hydrometra are
characterized by intrauterine storage of sterile mucous or
serous uid, respectively. The difference between these
conditions is the degree of hydration of the uid (40, 42).
Although bitches with hydrometra or mucometra may
develop an enlargement of the abdomen, more often there
are no clinical signs associated with those conditions (38).
However, diagnosing these conditions is important since
they may result in sub-fertility or infertility (21).
In contrast to mucometra or hydrometra, pyometra
is characterized by an inammatory component, and it is
associated with severe bacterial infection. Consequently,
bitches may develop clinical signs that require emergency
intervention, especially in cases when the cervix is closed.
Therefore, classication of pyometra in open-cervix or
close-cervix is clinically relevant. In cases of open-cervix
pyometra the purulent uterine exudate is drained through
the cervix, resulting in a sanguineous purulent malodorous
vulvar discharge that is easily identied. Conversely, in
cases of close-cervix pyometra the cervix remains closed
and the purulent exudate is retained within the uterus (Fig.
1), which increases the risk of endotoxemic shock and there
is even the possibility of uterine rupture. Although bitches
with any of these classications may develop septicemia, in
close-cervix pyometra the prognosis is worse, with quickly
progressing depression, polyuria, polydipsia, vomiting, and
diarrhea (38). In addition, the vulvar discharge in cases of
open-cervix pyometra allows the owner to early identify
the condition usually resulting in therapeutic intervention
before the development of systemic clinical changes.
Several changes in laboratorial parameters may
be observed in bitches with pyometra. Leukocytosis with
neutrophilia is the most frequent laboratorial nding in
cases of pyometra. However, in more severe cases there
may be leucopenia due to neutrophil sequester within the
uterine lumen. Endotoxic effects on the bone marrow may
result in anemia, thrombocytopenia and, consequently,
extramedullary hematopoiesis (20). Bitches with pyometra
may develop renal lesions, including tubular and glomerular
lesions, which may also result in blood or urinary
biochemical changes (32).
Pyometra may lead to endotoxemia and systemic
inammatory syndrome (SIRS). Clinical laboratory
analysis is a tool for determining the severity of this
systemic condition so it is useful for establishing a treatment
protocol and prognosis. Serum levels of prostaglandin F2α-
metabolite and C-reactive protein are increased in bitches
with pyometra, especially when pyometra is associated to
SIRS (20, 22).
Ultrasonographic examination is a useful technique
for diagnosis of uterine lesions in bitches. This technique
allows evaluation of uterine integrity, measurement of
the uterine wall, and assessment of cysts or luminal
distention (6). Uterine intraluminal uid can be identied
ultrasonographically and, usually, there are features that
may allow differentiating mucometra, hydrometra, or
Figure 1. Female dog with pyometra. Abdominal cavity with
marked enlargement of the uterus due to accumulation of purulent
exudate in a case of close-cervix pyometra.
Brazilian Journal of Veterinary Pathology. www.bjvp.org.br . All rights reserved 2007-2021.
Santana and Santos.; Canine pyometra – an update and revision of diagnostic terminology
Braz J Vet Pathol, 2021, 14(1), 1 – 8
DOI: 10.24070/bjvp.1983-0246.v14i1p1-8
3
pyometra (38). However, these uid characteristics are not
denitive parameters for the diagnosis. A study with bitches
in diestrus indicated that Doppler ultrasonography may
further support the diagnosis of pyometra. The uterine artery
of bitches with pyometra has higher end diastolic velocity,
higher peak systolic velocity, and lower resistance index,
compared to bitches with endometrial hyperplasia with or
without mucometra, or with a normal diestrus (5).
Stabilization of the general systemic condition of the
bitch followed by ovariosalpingohisterectomy still the most
recommended treatment for pyometra (24). Postsurgical
follow up should include assessment of kidney function and
antibiotic therapy for at least one week. When reproductive
activity is desirable, conservative medical treatment is a
possibility, but there is risk of recurrence (19, 34, 49).
Estrogen treatment has been proposed for
relaxing the cervix and promoting uterine contraction.
However, it also causes undesirable effects including
medullary suppression and vasodilatation that increases
absorption of toxins (49). Because of these side effects,
estrogen treatment is no longer recommended. Therapeutic
protocols usually have some common goals: (i) blocking
progesterone effects by promoting luteolysis or blocking
progesterone receptors; (ii) drainage of the purulent exudate
by relaxing the cervix and inducing uterine contractions
with prostaglandins or progesterone receptor antagonists;
(iii) prevent bacterial growth with antibiotic therapy; and
(iv) favor uterine regeneration, by prolonging the anestrus
by using mibolerone, an androgen receptor-agonist (49).
Pathogenesis of canine pyometra
The pathogenesis of canine pyometra is
multifactorial so bacterial infection, hormonal stimulus,
genetic predisposition, and other uterine lesions all play a
role in the development of the disease. However, hormonal
stimulus seems to be a key factor for triggering the
development of pyometra.
Female dogs are polytocous and have a monoestral
non-seasonal estrous cycle with spontaneous ovulations.
Importantly, intact bitches are repeatedly exposed
to progesterone during the diestrus, which length is
independent of pregnancy or matting. The diestrus or luteal
phase of estrus cycle persists for 50 to 80 days in non-
pregnant bitches and approximately 65 days in pregnant
bitches (7). Progesterone induces reduction in myometrial
contractility, decreased uterine blood ow, and impairment
of neutrophilic migration into the uterus (42). Furthermore,
progesterone alters endometrial innate immune response
to bacterial infections, inhibiting IFNϒ, TLR4, and TLR2
expression (46, 48). Importantly, pyometra is a disease that
develops during the diestrus (8, 12, 39), and the uterus has
higher levels of innate immune response to Escherichia
coli during the estrus when compared to the diestrus
(48). Together, these ndings support the notion that the
development of bacterial infection in cases of pyometra is
favored by the effect of progesterone on the uterus.
Lactoferrin, an iron-biding glycoprotein, that
plays an important antimicrobial role (50). Lactoferrin
expression in canine endometrium is higher during
proestrus and estrus compared to the diestrus, but it is
increased in cases of pyometra (29). Furthermore, the
endometrial surface is covered with mucin, particularly the
protein known as Muc1, which protects the endometrium
against infection by preventing bacterial adhesion (10, 18).
Possibly, reduction of lactoferrin and Muc-1 endometrial
expression during the diestrus may predispose to bacterial
infections by favoring bacterial adherence to endometrial
epithelium and colonization of the uterine environment
(26, 29). Although endometrial expression of lactoferrin is
increased in cases of pyometra, neutrophils display the most
intense immunostaining for lactoferrin, suggesting that this
increasing is due to neutrophilic inltration rather than an
actual increase in expression by endometrial cells (29).
Historically, pyometra has been associated with
CEH in bitches. An early and highly relevant study that
was based on experimental induction of CEH and pyometra
in neutered and hormonally-treated bitches supported
the hypothesis that pyometra is secondary to CEH, and
therefore the condition was named “CEH – pyometra
complex” (11). The author also suggested that the complex
was associated to high progesterone levels and that previous
hyperestrogenism could worsen the condition (12). In this
context, a classication including four types of canine
pyometra manifestation (types 1 through 4), based on
histopathological changes, was proposed.
Although the concept of “CEH – pyometra
complex” has been largely accepted by pathologists and
clinicians, this concept has been recently questioned.
Progesterone levels in bitches with pyometra are not higher
than in bitches without uterine lesions during diestrus
(24). Furthermore, endometrial hyperplasia and pyometra
are conditions that develop during the diestrus, affecting
animals of the same age range, suggesting that these changes
occur at the same time, but not necessarily that they have a
cause and effect relationship (8). Importantly, PEH has been
well characterized as an endometrial hyperplastic change
that is distinct from CEH, although both develop during the
diestrus (43). Indeed, a recent study demonstrated that there
is no signicant association between CEH and pyometra,
whereas pyometra is signicantly associated with PEH
(39). It is noteworthy that the seminal work by Dow (11,
12) was based on experimentally induced uterine changes,
which under a pathogenesis standpoint may not quite be a
surrogate of naturally occurring pyometra. Furthermore,
prior to the study by Schlafer and Gifford (43), very likely
PEH may have been extensively misdiagnosed as CEH, thus
supporting the concept of a “CEH – pyometra complex”
throughout the years. However, in spite of the fact that a
signicant association between PEH and pyometra has been
Brazilian Journal of Veterinary Pathology. www.bjvp.org.br . All rights reserved 2007-2021.
Santana and Santos.; Canine pyometra – an update and revision of diagnostic terminology
Braz J Vet Pathol, 2021, 14(1), 1 – 8
DOI: 10.24070/bjvp.1983-0246.v14i1p1-8
4
Figure 2. Female dog with pyometra. Moderately enlarged uterus,
with small amounts of intraluminal purulent exudates in a case of
open-cervis pyometra.
Figure 3. Female dog with pyometra. Markedly enlarged uterus
containing large amounts of a brown viscous purulent exudates in a
case of close-cervix pyometra (Cortesy of Dr. Silvia França Baêta).
Figure 4. Female dogs with pyometra. A. Endometrium with diffuse severe neutrophilic and lymphoplasmacytic inammatory inltrate
and accumulation of intraluminal neutrophils. Endometrial glands are moderately dilated. Luminal and supercial glandular endometrial
epithelium with decidual reaction, characterizing pseudoplacentational hyperplasia. Hematoxylin and eosin, bar = 500 µm. B. Luminal
endometrial hyperplasic epithelium, with papilliferous projections to the lumen and evident exocytosis of neutrophils. Endometrial
epithelial cells are columnar with nally vacuolated cytoplasm, characterizing a decidual reaction. Hematoxylin and eosin, bar = 100 µm.
C. Endometrial gland with myriad of intraluminal bacteria and eosinophilic brinous exudate. Hematoxylin and eosin, bar = 100 µm. D.
Uterine wall with necrosis, ulceration and loss of the endometrial layer, and accumulation of inammatory exudates in the uterine lumen.
Myometrium with diffuse and severe neutrophilic and lymphoplasmacytic inammatory inltrate. Hematoxylin and eosin, bar = 500 µm.
A B
C D
Brazilian Journal of Veterinary Pathology. www.bjvp.org.br . All rights reserved 2007-2021.
Santana and Santos.; Canine pyometra – an update and revision of diagnostic terminology
Braz J Vet Pathol, 2021, 14(1), 1 – 8
DOI: 10.24070/bjvp.1983-0246.v14i1p1-8
5
established (39), a cause and effect relationship between
these two conditions remains to be determined.
Development of CEH is thought to be initially due
to estrogen stimulation followed by progesterone inuence
(8, 47). Interestingly, there are evidences that insulin-like
grow factor 1 (IGF-1) may play a role in the development of
CEH (9). Conversely, the pathogenesis of PEH is not well
dened yet, but there are evidences that it may be associated
with high levels of prolactin and to the clinical manifestation
of pseudopregnancy (43).
Pathologic aspects of canine pyometra
There may be variable degrees of enlargement of the
uterus and accumulation of intraluminal exudate in cases of
pyometra. In less advanced cases or in cases of open-cervix,
uterine horns are mildly to moderately enlarged and there is
small to moderate amounts of intraluminal muco-purulent
exudate. In advanced or close-cervix cases of pyometra, the
uterus become markedly enlarged and full of large amounts of
fetid purulent exudate (42) (Fig. 2). The typical purulent uterine
exudate may eventually contain variable amounts of blood,
giving it a brown or red color with a strong fetid odor (Fig. 3).
Endometrium is usually hyperemic and thickened (42).
Grossly, prior to opening the uterine cavity,
mucometra or hydrometra are quite similar to pyometra, with
variable degrees of uterine enlargement. However, the uterine
contents are completely different among these conditions. In
both mucometra and hydrometra the intraluminal uid is
odorless, and may have a mucous appearance (35, 42).
In cases of endometrial hyperplasic lesions,
associated or not with pyometra, the uterine wall is
thickened, and cystic structures may be identied on the
endometrial surface or on endometrial cut surfaces, and
there may be variable amounts of uterine contents that may
be serous, mucous or mucous-purulent, this later when
associated with pyometra. When there is accumulation of
large amounts of uid in the lumen, the uterine wall and
endometrium may be thinner than normal. Although CEH
usually has a diffuse distribution, PEH is often segmental
(31, 41, 42), but an accurate gross differentiation between
these two conditions is usually not doable, especially when
they are associated with pyometra.
Histologically, advanced cases of pyometra
are characterized by a marked lymphoplasmacytic and
neutrophilic interstitial inammatory inltrate, with
accumulation of intraluminal neutrophils and eosinophilic
amorphous brinous exudate (35, 39) (Fig. 4A and 4B). In
some cases, it is possible to identify intralesional bacteria
in hematoxylin and eosin-stained sections (Fig. 4C). There
may also be extensive endometrial necrosis (Fig. 4D).
Microscopically, the intraluminal uid in cases of mucometra
or hydrometra is homogeneous and lightly eosinophilic, due
to its proteinaceous component, and absence of inammatory
cells neither in the tissues nor in the lumen.
Histologically, CEH and PEH have distinct
morphologic features. CEH is characterized by thickening
of the endometrium with moderate to severe ectasia of
endometrial glands, forming multiple cystic structures, but
both endometrial luminal and glandular epithelia are single
layered and cuboidal (39, 43) (Fig. 5). In cases of PEH, the
endometrium is also thickened, and there may be variable
degrees of endometrial glandular ectasia. However, the
luminal and supercial glandular endometrial epithelium is
hyperplasic, with one or multiple layers, often generating
papilliferous projections to the lumen. Importantly,
epithelial cells of the luminal epithelium as well as of the
supercial endometrial glands are large, columnar, with
a nally vacuolated cytoplasm, characterizing decidual
reaction, whereas the deeper and often cystically dilated
glands are lined by a single layered cuboidal to atten
epithelium without decidual reaction (39, 41, 42) (Fig. 4A).
Both CEH and PEH may be associated with endometrial
inammation and pyometra.
Readers must be aware that PEH is a condition
that is completely different from placentation sites (which
are physiological) or the pathologic change known as
subinvolution of placental sites. In healthy pregnant canine
uteruses, the endometrium has areas of zonary placentation
where there is attachment of the fetal placenta. Although it
is not within the scope of this review to describe it in detail,
different organized layers of endotheliochorial placentation
are histologically recognized (15). Subinvolution of
placental sites is associated with a delayed postpartum
uterine involution. Grossly there are multiple areas with
thickened, gray to brown and irregular endometrium
corresponding to the previous placental sites. Histologically,
there is hemorrhage, accumulation of necrotic debris and
brin, brosis and, importantly, remaining trophoblastic
cells (35).
Figure 5. Female dog with pyometra. Endometrial glands cystically
dilated and lined by a cuboidal to attened epithelium, characterizing
cystic endometrial hyperplasia, associated with an endometrial
lymphoplasmacytic inammatory inltrate and intraluminal
accumulation of neutrophils. Hematoxylin and eosin bar = 100 µm.
Brazilian Journal of Veterinary Pathology. www.bjvp.org.br . All rights reserved 2007-2021.
Santana and Santos.; Canine pyometra – an update and revision of diagnostic terminology
Braz J Vet Pathol, 2021, 14(1), 1 – 8
DOI: 10.24070/bjvp.1983-0246.v14i1p1-8
6
Comparative pathology of pyometra
Pyometra has been diagnosed in several domestic
and wild mammalian species, although less frequently than
in domestic dogs. Wild canids may develop pyometra and
CEH similar to domestic dogs (1, 2). There are evidence of
different susceptibility among wild canid species, with higher
susceptibility in African painted dogs and red wolves (2).
Domestic and wild cats often develop pyometra
and CEH with clinical and morphologic features that
are similar those conditions in domestic dogs (28, 33).
A study including Swedish insured cats demonstrated
an incidence of 0.17%, and a lethality rate of 5.6% (23).
Differences between cat breeds have been described,
with higher incidences in Sphynx followed by Siberian,
Ocicat, Korat, Siamese, Ragdoll, Maine coon, and Bengal,
suggesting a genetic predisposition to pyometra (23). The
lower incidence of pyometra in queens compared to bitches
is due to the fact that cats have induced ovulation, which
is triggered by vaginal stimulation, being less exposed to
prolonged periods of progesterone stimulus on the uterus
in the absence of pregnancy (44). Even when spontaneous
ovulation and pseudopregnancy happen in the queen, the
luteal phase has approximately 45 days, which is shorter
than a normal diestrus in bitches (44, 45).
A previous study described pyometra in seven
African lions (Panthera leo), two tigers (P. tigris), one
liger (lion-tiger hybrid), and one leopard (P. pardus) from
a sanctuary over a period of three years. Interestingly,
clinical signs, including lethargy, anorexia, vomiting and
vulvar discharge and abdominal ultrasonographic changes
were remarkably similar to those described in bitches
with pyometra. Additionally, the mean age that pyometra
was diagnosed in these felines was 12 years-old, which is
proportionally similar to mean age of affected female dogs
(33). Therefore, preventive ovariosalpingo-hysterectomy
should be considered in captive wild felids, when breeding
and reproduction is not desired (33). We had an unpublished
case of pyometra in a captive female African lion (Panthera
leo) that was successfully treated by surgery (Fig. 6).
Pyometra has also been reported in captive collared
peccary (Tayassu tajacu) (4), European hedgehog (Erinaceus
europaeus) (16), agouti (Dasyprocta aguti Linnaeus) (3)
and spotted seal (Phoca largha) (25). There are reports of
pyometra in guinea pigs and chinchillas (30), and in rodents
and lagomorphs, including mice and rats, in which it is
associated with Klebsiella oxytoca and Pasteurella multocida
systemic infections, respectively (36, 37).
Although other domestic species including
mares, cows, does, and ewes can develop pyometra, it is
not associated with endometrial hyperplasic changes.
Pyometra in cows is highly frequent, usually consequence
of a postpartum or postcoital infections (35). In the mare
pyometra is a consequence of vaginitis and cervicitis,
frequently associated to Streptococcus zooepidermicus (35).
Concluding remarks and perspectives
Canine pyometra is a common and life-threatening
disease of intact female dogs, which is often associated with
systemic complications, with a poor prognosis if untreated.
Multiple aspects of this disease remain unclear including
genetic predisposing factors, innate endometrial immune
response, and a thorough bacteriologic characterization
of isolates. Therefore, future studies may lead to a better
understanding of this disease, which may provide the basis
for the development of better preventive protocols.
Absence of signicant association between CEH
and pyometra, but a signicant association with PEH and
pyometra has been recently described (39). However,
the pathogenesis of PEH, and a possible cause and effect
relationship of this condition with canine pyometra remains
to be investigated. Another important aspect to be claried
in future studies, is whether PEH is a common change and
associated with pyometra in other domestic and wild species.
Figure 6. Female African lion (Panthera leo). Uterus. A. Formalin-
xed uterine horns markedly enlarged due to intraluminal
accumulation of purulent exudates in a case of pyometra. B. Cross
section of a uterine horn with an irregular endometrium, and the
lumen lled with large amounts of exudate.
A
B
Brazilian Journal of Veterinary Pathology. www.bjvp.org.br . All rights reserved 2007-2021.
Santana and Santos.; Canine pyometra – an update and revision of diagnostic terminology
Braz J Vet Pathol, 2021, 14(1), 1 – 8
DOI: 10.24070/bjvp.1983-0246.v14i1p1-8
7
Although the concept of “CEH – pyometra
complex” was soundly based on the seminal experimental
work by Dow (11, 12), it is now clear that pyometra is
more often associated with PEH than with CEH (39).
Therefore, we strongly recommend that the diagnostic
terms “pyometra”, “pseudoplacentational endometrial
hyperplasia”, and “cystic endometrial hyperplasia” should
be employed separately and referring to specic uterine
pathologic changes. Furthermore, the concept of “CEH –
pyometra complex” has become obsolete under the light of
recent studies (39, 43) so it should no longer be employed
as a synonymous of pyometra.
Acknowledgements
Work in RLS lab is supported by CNPq (Conselho
Nacional de Desenvolvimento Cientíco e Tecnológico,
Brazil), FAPEMIG (Fundação de Amparo a Pesquisa do
Estado de Minas Gerais, Brazil), and CAPES (Coordenação
de Aperfeiçoamento de Pessoal de Nível Superior, Brazil).
RLS has a fellowship from CNPq (Brazil).
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