Diagnostic and Prognostic Markers for Uterine Diseases in Dogs

Transcription

1 Reprod Dom Anim 49 (Suppl. 2), (2014); doi: /rda ISSN Diagnostic and Prognostic Markers for Uterine Diseases in Dogs R Hagman Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden Contents Common uterine diseases in female dogs include cystic endometrial hyperplasia (CEH), mucometra, hydrometra and pyometra. It is important in clinical practice to recognize pyometra because it is potentially life-threatening due to the systemic illness induced by bacterial infection of the uterus. In contrast, the uterine content is sterile in CEH and mucometra/ hydrometra, and clinical signs are mostly mild or absent. Optimal treatment depends on the type of uterine disease and its severity, but diagnosis and prognosis determination may be challenging and the diseases difficult to separate clinically. Diagnostic findings or biomarkers that may aid in the differentiation of the diseases are valuable, especially when several bitches are admitted with a fluid-filled uterus during night-time, and it has to be decided which patient to operate on first. Additionally, some variables may indicate outcome as measured by mortality or morbidity. If the uterus is not enlarged or fluid-filled, detection of uterine disease can be even more difficult. In this study, clinically useful variables with possible diagnostic or prognostic value for uterine diseases in dogs are discussed. Introduction Uterine diseases such as cystic endometrial hyperplasia (CEH), mucometra, hydrometra and pyometra are common in countries where neutering healthy dogs is not generally practised (Dow 1959a; Niskanen and Thrusfield 1998; Egenvall et al. 2001; Ortega-Pacheco et al. 2012). Cystic endometrial hyperplasia, defined as proliferation of endometrial glands, endometrial hyperplasia and formation of cysts, can be present with or without fluid accumulating in the uterus (Dow 1959a). Mucometra, hydrometra and pyometra are defined by the type of fluid present in the uterus and the degree of hydration of the mucin. In mucometra, the uterine content is sero-mucoid to mucoid; in hydrometra, it is serous and in pyometra, purulent or haemopurulent (Dow 1959a). Hemometra, in which the uterine content is haemorrhagic, is reported more rarely (Troxel et al. 2002; Barrand 2009). Other uterine diseases such as inflammation of the endometrium (endometritis) and uterine neoplasia are less commonly diagnosed in clinical practice (Mir et al. 2013). Proliferative and cystic conditions such as pseudo-placentational endometrial hyperplasia (PEH) have also been described (Schlafer and Gifford 2008). Cystic endometrial hyperplasia, mucometra/hydrometra and pyometra are associated with metoestrus and middle-aged to older animals (Dow 1959a; Egenvall et al. 2001). It is believed that repeated progesterone influence during each metoestrus in cycling bitches leads to the gradual development of CEH, and subsequent fluid accumulation and/or bacterial infection, with the most severe end stage being pyometra (Teunissen 1952; Dow 1959a; Hardy and Osborne 1974). However, muco-, hydro- or pyometra can also be present without any signs of CEH (De Bosschere et al. 2001; Verstegen et al. 2008). Progesterone also contributes to the development of disease because the influence of this hormone (especially after previous oestrogen influence) renders the uterus susceptible to bacterial infection and pyometra (Teunissen 1952; Dow 1959b). The bacteria, most commonly isolated from pyometra, Escherichia coli (E. coli) adhere to receptors in progesterone-stimulated endometrium and have certain virulence attributes that contribute to establishment of infection (Sandholm et al. 1975; Krekeler et al. 2012). Although much research has been carried out since the 1930s, the complex aetiology and pathogenesis of uterine disease are not completely understood (Benesch and Pommer 1930; Verstegen et al. 2008). Cystic endometrial hyperplasia and mucometra/ hydrometra are common incidental findings identified after ovariohysterectomy, post-mortem or after cytological or histological examination of the uterus (Dow 1959a). Diagnosis can be challenging, and clinical signs are often absent or only noticed as sub- or infertility (Verstegen et al. 2008; Mir et al. 2013). Detection of CEH and mucometra/hydrometra is important not only because they lead to decreased fertility in breeding animals but also because there is likely an increased risk of developing more severe uterine disease such as pyometra. Diagnosis of pyometra is, in contrast, generally straightforward because of the characteristic history and clinical signs of disease (Hardy and Osborne 1974; Børresen 1979). Most often the disease is diagnosed within 2 months after oestrus, and lethargy, decreased appetite, increased urination, increased thirst and the presence of purulent or haemopurulent vaginal discharge are frequently reported (Hardy and Osborne 1974; Børresen 1979). The clinical picture can, however, sometimes be vague, especially when vaginal discharge is absent. Due to the potentially lethal systemic effects induced by the disease, prognostic markers for mortality, morbidity and identification of sepsis are in high demand (Hardie 1995; Fransson et al. 2007). Additionally, diagnostic tools that may differentiate pyometra from mucometra/hydrometra when a fluid-filled uterus is detected would also be clinically useful. Prognostic Indicators in Pyometra Pyometra is characterized by bacterial infection and inflammation with pus accumulating in the uterus in

2 Markers for Uterine Disease in Dogs 17 combination with systemic illness (Hardy and Osborne 1974). The disease is regarded as an emergency because early diagnosis and rapid therapeutic intervention are necessary to prevent a fatal outcome (Maretta et al. 1989; Wheaton et al. 1989; Hardie 1995). The safest and most effective treatment is ovariohysterectomy which is performed as soon as the general condition is stabilized (Hardy and Osborne 1974). Pure medical treatment is sometimes an option to preserve fertility, but with the risk of progressing illness as long as the infection remains in the body. Recurrence of the condition after treatment is also possible because the uterus might be predisposed for infection (Gobello et al. 2003; Fieni 2006; Verstegen et al. 2008). Pathologies such as ovarian cysts, extensive CEH and old age have been associated with poor prognosis after medical treatment (Jurka et al. 2010). At admission, it is important to identify patients that require more intensive monitoring and care to survive because uterine rupture, endotoxemia and sepsis may transform a clinically stable pyometra to an emergency in a few hours (Wheaton et al. 1989; Hardie 1995; Okano et al. 1998). Sepsis defined as systemic inflammatory response syndrome (SIRS), caused by infection is present in most dogs with pyometra and has been associated with increased hospitalization and mortality (Brady and Otto 2001; Fransson et al. 2007). The mortality in pyometra is relatively low (3 4%) but is increased in cases where complications such as septic peritonitis develop (Egenvall et al. 2001). In pyometra, the degree of systemic illness is reflected as more or less severe alterations of haematological and biochemical variables. Normocytic, normochromic anaemia and leucocytosis with neutrophilia and left shift are often observed (Hardy and Osborne 1974; Børresen 1980). Occasionally, leucopenia is present (Hardy and Osborne 1974; Børresen 1980). Acute-phase protein (APP) concentrations are generally increased in pyometra and may predict sepsis and the differentiation of pyometra from mucometra/hydrometra (Fransson et al. 2004). Blood concentrations of one of the major APPs in dogs, C-reactive protein (CRP), are increased in SIRS-positive pyometra patients vs. SIRS-negative pyometra patients, and the levels are associated with morbidity as measured by length of hospitalization (Fransson et al. 2004). The APPs subsequently decrease after surgical treatment and can be used to assess recovery and the presence of complications with an inflammatory component during the post-operative period (Dabrowski et al. 2009). Repeated measurements of APPs such as CRP, serum amyloid A and haptoglobin may thus serve as indictors for complications. Endotoxemia, disseminated bacterial infection and coagulation disturbances may lead to dysfunction of several organs (Okano et al. 1998; Hagman et al. 2006a,b). If multiple organ dysfunction develops, the prognosis for survival is poor (Brady and Otto 2001; Conti-Patara et al. 2012). Renal dysfunction has been reported in many bitches with pyometra ( Asheim 1963; De Schepper et al. 1987). Renal failure and death due to end-stage kidney disease have also been described (Capiau et al. 1987; Trasch et al. 2003; Heiene et al. 2007). Increased urinary protein to creatinine ratio and persistent proteinuria after treatment of pyometra are noteworthy because these findings indicate renal disease that may require special attention (Heiene et al. 2007; Maddens et al. 2011). Intrahepatic cholestasis is a common finding in pyometra, most likely caused by endotoxemia (Børresen 1980). The blood coagulation can be disturbed, and if disseminated intravascular coagulation (DIC) develops, with concurrent thrombocytopenia and anaemia as frequent findings in pyometra, the prognosis for survival is poor (Hardy and Osborne 1974; Børresen 1979). Higher blood concentrations of endotoxin have been related to poor outcome, that is, death in dogs with the disease and a rapid, reliable and cost-effective method for analysis would be clinically useful (Okano et al. 1998). Endotoxin concentrations are, however, challenging to measure, which may explain why endotoxemia has not consistently been demonstrated in pyometra (Fransson et al. 1997; Hagman et al. 2006a). Currently, no method is available for routine clinical use in dogs. Analysis of a more stable indicator for endotoxin release, such as prostaglandin F 2a metabolite (PGM), could be an alternative if a cage-side test was developed (Hagman et al. 2006b). It has previously been shown that PGM analysis has prognostic value in pyometra as an indicator of sepsis (higher concentrations in SIRS-positive bitches) and also for morbidity as measured by duration of hospitalization (Hagman et al. 2006b). The levels of PGM decrease after surgery similar to the APPs, but longer follow-up studies have not yet been performed (Vandeplassche et al. 1991). Neutrophilic cytoplasmatic toxicity is relatively common in pyometra and has been associated with poorer prognosis in other bacterial diseases (Aroch et al. 2005). In a recent study using pyometra as a model for sepsis in an intensive care unit, central venous oxygen saturation, base deficit and lactate levels had clinical value for determining prognosis. In that study, bitches with severe sepsis or septic shock that had higher central venous oxygen saturation and lower base deficit were more likely to survive (Conti-Patara et al. 2012). Differentiation of Pyometra and Mucometra/ Hydrometra Pyometra is regarded as the most severe end stage of the gradually developing CEH pyometra complex, but can also be present with or without CEH (Dow 1959b). It has been suggested that the CEH pyometra complex should be divided into two diseases, CEH/mucometra vs. endometritis/pyometra, depending on the clinical signs and inflammatory response induced (De Bosschere et al. 2001). In mucometra, hydrometra and hemometra, there is no bacterial infection and thus little risk of developing endotoxemia and sepsis induced by the uterine disease. If several dogs are admitted with a fluid-filled uterus, it is valuable to differentiate bitches that are suffering from potentially life-threatening disease, that is, pyometra, from those with mucometra or hydrometra with low risk of developing SIRS Several clinical and laboratory findings are helpful for this differentiation. In bitches with pyometra, the

3 18 R Hagman general condition is more depressed, and the case history and clinical signs more commonly include lethargy and gastrointestinal disturbances (Fransson et al. 2004; Hagman et al. 2006b). More than three clinical signs of disease are also indicative of pyometra rather than mucometra/hydrometra (Fransson et al. 2004). As for laboratory variables, total white blood cell count, band neutrophils, percentage of band neutrophils, segmented neutrophils, monocytes and lymphocytes are higher in pyometra than in mucometra (Fransson et al. 2004; Hagman et al. 2006b). Additionally, cholesterol levels are increased, and albumin levels decreased in pyometra vs. mucometra/hydrometra (Hagman et al. 2006b). In one study, the percentage of band neutrophils had the highest sensitivity (94%) and a specificity of 70%, in the prediction of pyometra vs. mucometra, if used as a single test (Fransson et al. 2004). If a combination of percentage of band neutrophils and CRP was used, the sensitivity and specificity were increased (97.7% and 75%, respectively; Fransson et al. 2004). In another study, PGM alone was shown to have an even higher sensitivity (96.6%) and specificity (90.9%) than percentage of band neutrophils for the differentiation of pyometra vs. mucometra, and if combining PGM and percentage of band neutrophils, a complete differentiation of pyometra vs. mucometra was possible (sensitivity 100%, specificity 81.8%; Hagman et al. 2006b). Although the specificity was less than 100%, meaning that 18.2% of mucometra cases will be falsely diagnosed as pyometra, it is preferred in clinical practice to have a diagnostic test with high sensitivity as surgery of a false positive pyometra (mucometra) is less risky than in a wrongly diagnosed pyometra. Radiography may detect uterine enlargement and peritonitis. Ultrasonography has the advantage of determining whether fluid is present in the uterus and may also indicate the type of fluid based on its echogenicity (Bigliardi et al. 2004). Additionally, it is possible to assess the uterine tissue, signs of neoplasia, the ovarian status and the presence of endometrial cysts as small as 1 mm in diameter. Other causes for uterine enlargement such as pregnancy may be identified or ruled out using ultrasonography, and signs indicative of peritonitis can be observed. Importantly, bacteriological sampling from the cranial vagina is not indicative of infection because the vaginal flora of healthy bitches usually contain the same bacterial species as in bitches with pyometra (Bjurstro m 1993; Groppetti et al. 2012). Vaginal cytology can be normal in closed-cervix pyometra and mucometra/hydrometra and is therefore of less value for diagnosing these diseases compared with delayed uterine involution (SIPS) where trophoblast-like cells are observed (Groppetti et al. 2012). Because identification of a fluid-filled uterus in metoestrus is pathological, most non-breeding bitches are subjected to ovariohysterectomy regardless of whether suffering from mucometra/hydrometra or pyometra. In those cases, post-operative macroscopic examination in combination with histopathological examination of the uterus and/or bacteriological culturing of the uterine content provides the definitive diagnosis. Diagnostic Indicators of Diseases without Uterine Enlargement Diagnosis of uterine conditions with no fluid in the uterus or uterine enlargement remains challenging. The case history may be vague and includes infertility, subfertility or pregnancy loss (Mir et al. 2013). Many bitches with uterine inflammation have no signs of illness, and vaginal cytology is in most cases normal (Verstegen et al. 2008; Mir et al. 2013). Vaginal cytological examination alone therefore cannot rule out uterine inflammation but may still be helpful in the diagnostic work-up if signs of infection and inflammation such as largely increased numbers of bacteria, pus or bacteria engulfed by neutrophils are demonstrated in cases where the uterus and ovaries are normal by ultrasonography. Ultrasonography is the diagnostic imaging technique preferred because it is cost-effective and provides detailed information of endometrial thickness and appearance and the presence of fibrosis or cysts (Bigliardi et al. 2004). Although laboratory investigations may detect unspecific inflammation, cytological and/or histological examination of the uterus is generally necessary for definitive diagnosis of mild proliferative and cystic conditions. The value of endoscopic transcervical uterine biopsies has been questioned but recently shown useful for diagnosing uterine inflammation, CEH and fibrosis (Gu nzel-apel et al. 2001; Christensen et al. 2012; Mir et al. 2013). Transcervical biopsy sampling has the advantage of not requiring general anaesthesia, and widespread pathological changes can be identified. Depending on the sample sites selected, an area of local or more severe disease could, however, remain undetected. Full thickness wall biopsy sampling via celiotomy and general anaesthesia allows for uterine palpation/visual identification of areas optimal to be biopsied (Christensen et al. 2012; Mir et al. 2013). The risk of inducing pyometra when performing biopsies should, however, be considered (Gu nzel-apel et al. 2001; Christensen et al. 2012; Mir et al. 2013). Analysis of endometrial cytology samples, which can also be obtained by uterine flushing, may provide information on pathologic conditions (Watts and Wright 1995; Watts et al. 1997; Groppetti et al. 2010). Sensitive and specific diagnostic markers for early diagnosis of uterine diseases are warranted. Early diagnosis and treatment improve the outcome and prevent progression to more severe disease and complications associated with advancing pyometra and sepsis. Ideally, such markers could also be used to evaluate the treatment response. The expression of and products of certain up-regulated genes in the uterine tissue may be useful for diagnostic or prognostic purposes (Chu et al. 2002; Hagman et al. 2009a,b; Chotimanukul and Sirivaidyapong 2011; Silva et al. 2012). To be able to detect and evaluate suitable markers, it is necessary to obtain more knowledge about the aetiology, pathogenesis and clinical findings of the different uterine diseases. Acknowledgements S. Scott Robson is acknowledged for language review of the manuscript.

4 Markers for Uterine Disease in Dogs 19 Conflict of Interest None of the authors have any conflicts of interest to declare. References Aroch I, Klement E, Segev G, 2005: Clinical, biochemical, and hematological characteristics, disease prevalence, and prognosis of dogs presenting with neutrophil cytoplasmic toxicity. J Vet Intern Med 19, Asheim A, 1963: Renal Injury in Dogs with Pyometra. Doctoral Thesis. Swedish University of Agricultural Sciences, Uppsala, p Barrand KR, 2009: Unilateral uterine torsion associated with hematometra and cystic endometrial hyperplasia in a bitch. Vet Rec 164, Benesch F, Pommer A, 1930: Zur klinische Röntgendiagnose der Pyometra und Hydrometra bei Fleischfressern. Wiener Tierärtz Monatsschr 17, Bigliardi E, Parmigiani E, Cavirani S, Luppi A, Bonati L, Corradi A, 2004: Ultrasonography and cystic endometrial hyperplasia pyometra complex in the bitch. Reprod Dom Anim 39, Bjurström L, 1993: Aerobic bacteria occurring in the vagina of bitches with reproductive disorders. Acta Vet Scand 34, Børresen B, 1979: Pyometra in the dog a pathophysiological investigation. II. Anamnestic, clinical and reproductive aspects. Nord Vet Med 31, Børresen B, 1980: Pyometra in the dog a pathophysiological investigation. IV. Functional derangement of extragenital organs. Nord Vet Med 32, Brady CA, Otto CM, 2001: Systemic inflammatory response syndrome, sepsis, and multiple organ dysfunction. Vet Clin North Am Small Anim Pract 31, , v vi. Capiau E, De Schepper J, Van Der Stock J, 1987: Renal failure and serum enzymes in 127 dogs with pyometra. Vlaams Diergeneeskd Tijdschr 56, Chotimanukul S, Sirivaidyapong S, 2011: Differential expression of Toll-like receptor 4 (TLR4) in healthy and infected canine endometrium. Theriogenology 76, Christensen BW, Schlafer DH, Agnew DW, Wang C, Kozlowski C, Asa CS, 2012: Diagnostic value of transcervical endometrial biopsies in domestic dogs compared with full-thickness uterine sections. Reprod Dom Anim Suppl 47, Chu PY, Salamonsen LA, Lee CS, Wright PJ, 2002: Matrix metalloproteinases (MMPs) in the endometrium of bitches. Reproduction 123, Conti-Patara A, de Araujo Caldeira J, de Mattos-Junior E, de Carvalho Hda S, Reinoldes A, Pedron BG, Patara M, Francisco Talib MS, Faustino M, de Oliveira CM, Cortopassi SR, 2012: Changes in tissue perfusion parameters in dogs with severe sepsis/septic shock in response to goal-directed hemodynamic optimization at admission to ICU and the relation to outcome. J Vet Emerg Crit Care 22, Dabrowski R, Kostro K, Lisiecka U, Szczubia M, Krakowski L, 2009: Usefulness of C-reactive protein, serum amyloid A component, and haptoglobin determinations in bitches with pyometra for monitoring early post-ovariohysterectomy complications. Theriogenology 72, De Bosschere H, Ducatelle R, Vermeirsch H, Van Den Broeck W, Coryn M, 2001: Cystic endometrial hyperplasia pyometra complex in the bitch: should the two entities be disconnected? Theriogenology 55, De Schepper J, Van Der Stock J, Capiau E, De Cock I, 1987: Renal injury in dogs with pyometra. Tijdschr Diergeneeskd 112, Dow C, 1959a: The cystic hyperplasia pyometra complex in the bitch. J Comp Pathol 69, Dow C, 1959b: Experimental reproduction of the cystic hyperplasia pyometra complex in the bitch. J Pathol Bacteriol 78, Egenvall A, Hagman R, Bonnett BN, Hedhammar A, Olson P, Lagerstedt AS, 2001: Breed risk of pyometra in insured dogs in Sweden. J Vet Intern Med 15, Fieni F, 2006: Clinical evaluation of the use of aglepristone, with or without cloprostenol, to treat cystic endometrial hyperplasia-pyometra complex in bitches. Theriogenology 66, Fransson B, Lagerstedt AS, Hellmen E, Jonsson P, 1997: Bacteriological findings, blood chemistry profile and plasma endotoxin levels in bitches with pyometra or other uterine disease. J Vet Med Series A 44, Fransson BA, Karlstam E, Bergström A, Park JS, Evans MA, Ragle CA, 2004: C-reactive protein in the differentiation of pyometra from cystic endometrial hyperplasia/mucometra in dogs. J Am Anim Hosp Assoc 40, Fransson BA, Lagerstedt A-S, Bergstrom A, Hagman R, Park JS, Chew BP, Evans MA, Ragle CA, 2007: C-reactive protein, tumor necrosis factor alpha, and interleukin-6 in dogs with pyometra and SIRS. J Vet Emerg Crit Care 17, Gobello C, Castex G, Klima L, Rodriuez R, Corrada Y, 2003: A study of two protocols combining aglepristone and cloprostenol to treat open cervix pyometra in the bitch. Theriogenology 60, Groppetti D, Pecile A, Arrighi S, Di Giancamillo A, Cremonesi F, 2010: Endometrial cytology and computerized morphometric analysis of epithelial nuclei: a useful tool for reproductive diagnosis in the bitch. Theriogenology 73, Groppetti D, Pecile A, Barbero C, Martino PA, 2012: Vaginal bacterial flora and cytology in proestrous bitches: role on fertility. Theriogenology 77, Gu nzel-apel AR, Wilke M, Aupperle H, Schoon HA, 2001: Development of a technique for transcervical collection of uterine tissue in bitches. J Reprod Fertil Suppl 57, Hagman R, Kindahl H, Lagerstedt AS, 2006a: Pyometra in bitches induces elevated plasma endotoxin and prostaglandin F2alpha metabolite levels. Acta Vet Scand 47, Hagman R, Kindahl H, Fransson BA, Bergström A, Ström-Holst B, Lagerstedt AS, 2006b: Differentiation between pyometra and cystic endometrial hyperplasia/mucometra in bitches by prostaglandin F2alpha metabolite analysis. Theriogenology 66, Hagman R, Reezigt BJ, Bergström Ledin H, Karlstam E, 2009a: Blood lactate levels in 31 female dogs with pyometra. Acta Vet Scand 51, 2. Hagman R, Rönnberg E, Pejler G, 2009b: Canine uterine bacterial infection induces upregulation of proteolysis-related genes and downregulation of homeobox and zinc finger factors. PLoS ONE 4, e8039. Hardie EM, 1995: Life-threatening bacterial infection. Comp Cont Educ Pract Vet 17, Hardy RM, Osborne CA, 1974: Canine pyometra: pathophysiology, diagnosis and treatment of uterine and extra-uterine lesions. J Am Anim Hosp Assoc 10, Heiene R, Kristiansen V, Teige J, Jansen JH, 2007: Renal histomorphology in dogs with pyometra and control dogs, and long term clinical outcome with respect to signs of kidney disease. Acta Vet Scand 49, 13. Jurka P, Max A, Hawrynska K, Snochowski M, 2010: Age-related pregnancy results and further examination of bitches after aglepristone treatment of pyometra. Reprod Dom Anim 45, Krekeler N, Marenda MS, Browning GF, Holden KF, Charles JA, Wright PJ, 2012: Uropathogenic virulence factor FimH facilitates binding of uteropathogenic Escherichia coli to canine endometrium. Comp Immunol Microbiol Infect Dis 35, Maddens B, Heiene R, Smets P, Svensson M, Aresu L, van der Lugt J, Daminet S, Meyer E, 2011: Evaluation of kidney injury in dogs with pyometra based on proteinuria, renal histomorphology, and urinary biomarkers. J Vet Intern Med 25, Marretta SM, Matthiesen DT, Nichols R, 1989: Pyometra and its complications. Probl Vet Med 1, Mir F, Fontaine E, Albaric O, Greer M, Vannier F, Schlafer DH, Fontbonne A, 2013: Findings in uterine biopsies obtained by laparotomy from bitches with unexplained infertility or pregnancy loss: an observational study. Theriogenology 79, Niskanen M, Thrusfield MV, 1998: Associations between age, parity, hormonal therapy and breed, and pyometra in Finnish dogs. Vet Rec 143, Okano S, Tagawa M, Takase K, 1998: Relationship of the blood endotoxin

5 20 R Hagman concentration and prognosis in dogs with pyometra. J Vet Med Sci 60, Ortega-Pacheco A, Gutierrez-Blanco E, Jimenez-Coello M, 2012: Common lesions in the female reproductive tract of dogs and cats. Vet Clin North Am Small Anim Pract 42, Sandholm M, Vasenius H, Kivistö AK, 1975: Pathogenesis of canine pyometra. J Am Vet Med Assoc 167, Schlafer DH, Gifford AT, 2008: Cystic endometrial hyperplasia, pseudo-placentational endometrial hyperplasia, and other cystic conditions of the canine and feline uterus. Theriogenology 70, Silva E, Leit~ao S, Henriques S, Kowalewski MP, Hoffmann B, Ferreira-Dias G, da Costa LL, Mateus L, 2012: Gene transcription of TLR2, TLR4, LPS ligands and prostaglandin synthesis enzymes are up-regulated in canine uteri with cystic endometrial hyperplasia-pyometra complex. J Reprod Immunol 84, Teunissen GHB, 1952: The development of endometritis in the dog and the effect of oestradiol and progesterone on the uterus. Acta Endocrinol 9, Trasch K, Wehrend A, Bostedt H, 2003: Follow-up examinations of bitches after conservative treatment of pyometra with the antigestagen aglepristone. J Vet Med A Physiol Pathol Clin Med 50, Troxel MT, Cornetta AM, Pastor KF, Hartzband LE, Besancon MF, 2002: Severe hematometra in a dog with cystic endometrial hyperplasia/pyometra complex. J Am Anim Hosp Assoc 38, Vandeplassche M, Coryn M, De Schepper J, 1991: Pyometra in the bitch: Cytological, bacterial, histological and endocrinological characteristics. Vlaams Diergeneeskd Tijdschr 60, Verstegen J, Dhaliwal G, Verstegen-Onclin K, 2008: Mucometra, cystic endometrial hyperplasia, and pyometra in the bitch: advances in treatment and assessment of future reproductive success. Theriogenology 70, Watts JR, Wright PJ, 1995: Investigating uterine disease in the bitch: uterine cannulation for cytology, microbiology and hysteroscopy. J Small Anim Pract 36, Watts JR, Wright PJ, Lee CS, Whithear KG, 1997: New techniques using transcervical uterine cannulation for the diagnosis of uterine disorders in bitches. J Reprod Fertil Suppl 51, Wheaton LG, Johnson AL, Parker AJ, Kneller SK, 1989: Results and complications of surgical treatment of pyometra: a review of 80 cases. J Am Anim Hosp Assoc 25, Author s address (for correspondence): Ragnvi Hagman, Department of Clinical Sciences, Swedish University of Agricultural Sciences, Box 7054, SE Uppsala, Sweden. ragnvi.hagman@slu.se