Catestatin, vasostatin, cortisol, and visual analog scale scoring for stress assessment in healthy dogs.

The neuroendocrine glycoprotein chromogranin A is a useful biomarker for stress in humans. Chromogranin A epitopes catestatin and vasostatin can be measured in dogs using radioimmunoassays. The objective of this study was to evaluate catestatin and vasostatin as canine stress biomarkers in a clinical setting. Blood and saliva were collected from 33 healthy dogs that were familiar with sampling procedures and the animal hospital environment (control group) and 30 healthy dogs that were unacquainted (stress group). During sampling, stress behavior was scored by the same observer using visual analog scale (VAS). Plasma was analyzed for catestatin and vasostatin, serum for cortisol, and saliva for catestatin. Differences between groups were analyzed using two-sample t-tests and P<0.05 was considered significant. Stress behavior VAS score in the control group was significantly lower than in the stress group during blood (P=0.002) and saliva (P=0.0009) sampling. Serum cortisol and saliva catestatin concentrations in the stress group were higher than the control group (P=0.003 and P<0.0001, respectively). Serum cortisol concentrations were correlated with those of saliva (r=0.34, P=0.04) and plasma catestatin (r=0.29, P=0.03). Plasma catestatin and vasostatin did not differ significantly between groups. In conclusion, concentrations of saliva catestatin, and serum cortisol, and stress behavior VAS scores were significantly higher in the stress group. The results indicate that saliva catestatin may be useful as a biomarker for acute psychological stress in dogs.

Molecular aspects of uterine diseases in dogs.

Uterine diseases are common in dogs, particularly in countries where elective spaying is not usually performed. The associated clinical illnesses may be of varying degree ranging from merely decreased fertility to a critical pyometra requiring intensive care to survive. The diagnosis of some uterine diseases is generally uncomplicated, such as in a classic pyometra presenting with enlarged, fluid-filled uterus, purulent vaginal discharge and characteristic signs of illness or in other disorders associated with uterine enlargement. However, it can be more puzzling in diseases with normal uterine size and very mild or obscure clinical signs. It is important to recognize the uterine diseases early because of the risk of potentially life-threatening complications such as sepsis developing if treatment is delayed in cases where bacterial infection is present. In breeding bitches, an early diagnosis, that is when the disease has not developed extensively, will increase the possibility of non-surgical treatment options without increased risk and thereby also increasing chances of maintained fertility. Early diagnosis and treatment initiation are thus favourable for complete recovery, also in less severe uterine diseases and those without infection. Molecular markers are molecules in biological samples that can be measured for diagnostic purposes, outcome prediction, and for gaining more information about different physiological and pathological conditions. Examples of commonly evaluated markers include laboratory variables analysed in blood, urine, cytological or tissue biopsy samples. Regarding the genetic pre-disposition for different uterine diseases in dogs, information is lacking. Recently, the global gene expression in uterine tissue in dogs has been investigated more closely, and newly developed technologies provide excellent opportunities for identifying molecular markers worth exploring further. The focus of this review article is to highlight findings on markers relevant for diagnosis, prediction of prognosis and treatment outcome in the most common uterine diseases in dogs.

Canine pyometra: What is new?

Pyometra is a common disease in countries where elective spaying is not routinely performed. Hormonal and bacterial factors are fundamental in the pathogenesis of the disease, which manifests itself as a potentially life-threatening bacterial infection of the uterus. Surgical ovariohysterectomy is the safest and most effective treatment for pyometra, and it has recently been shown that laparoscopically assisted methods for surgical treatment are feasible to use in selected cases. New protocols for improved medical treatment alternatives have also been tested with promising results. To be able to predict outcome and presence of complications early would be valuable in clinical practice for optimizing therapy and increasing survival. Results of commonly investigated clinical and laboratory investigations have been shown to be useful as predictive markers, with leucopenia being associated with increased risk of peritonitis as well as prolonged post-operative hospitalization after surgical treatment. A cage-side rapid and cost-effective diagnostic test would be highly valuable in clinical practice, and detection of pyometra-specific upregulated genes in the uterus and the corresponding products is a potential start in identifying novel markers suitable for such as test. The focus of the present review is to highlight recent findings on pathogenesis, prediction of outcome, diagnosis and treatment. Additionally, central research questions and suggestions for future investigations about several aspects of canine pyometra will be addressed.

Increased serum C-reactive protein concentrations in dogs with congestive heart failure due to myxomatous mitral valve disease.

Cardiovascular disease in humans and dogs is associated with mildly increased circulating concentrations of C-reactive protein (CRP). Few studies have evaluated associations between circulating CRP and canine myxomatous mitral valve disease (MMVD) and the results reported have been divergent. The aim of this study was to investigate whether serum concentrations of CRP, determined using a novel automated canine-specific high-sensitivity CRP assay (Gentian hsCRP), were associated with severity of MMVD and selected clinical variables in dogs. The study included 188 client-owned dogs with different severities of MMVD. Dogs were classified based on ACVIM consensus statement guidelines (group A, n = 58; group B1, n = 56; group B2, n = 38; group C, n = 36). Data were analysed using descriptive statistics and multiple regression analysis. Dogs with congestive heart failure (CHF; group C) had significantly higher CRP concentrations (median, 2.65 mg/L; quartile 1-quartile 3, 1.09-5.09) compared to dogs in groups A (median, 0.97 mg/L; quartile 1-quartile 3, <0.50-1.97; P = 0.001), B1 (median, 0.78 mg/L; quartile 1-quartile 3, <0.50-1.73, P <0.0001) and B2 (median, 0.60 mg/L; quartile 1-quartile 3, <0.50-1.23; P <0.0001). Other variables reflecting disease severity, including left atrial to aortic root ratio (P = 0.0002, adjusted r(2) = 0.07) and left ventricular end-diastolic diameter normalised for bodyweight (P = 0.0005, adjusted r(2) = 0.06), were positively associated with CRP concentration, but the association disappeared if dogs with CHF were excluded from analysis. In conclusion, slightly higher CRP concentrations were found in dogs with CHF whereas severity of asymptomatic MMVD showed no association with CRP concentrations.

Metabolic and Hormonal Response to a Feed-challenge Test in Lean and Overweight Dogs.

BACKGROUND: Obese dogs risk poor life quality, creating a need for increased knowledge of metabolism in overweight dogs. OBJECTIVES: Investigate postprandial metabolic and hormonal responses to a high-fat mixed-meal in dogs and responses of lean versus overweight dogs. ANIMALS: Twenty-eight healthy intact male Labrador Retrievers were included. METHODS: Prospective observational study. Twelve dogs were grouped as lean (body condition score (BCS 4-5), 10 as slightly overweight (BCS 6), and 6 as overweight (BCS 6.5-8) on a 9-point scale. After an overnight fast, urine and blood samples were collected. Dogs were then fed a high-fat mixed-meal, and blood was collected hourly for 4 hours and urine after 3 hours. RESULTS: Postprandial concentrations of insulin and glucagon were increased at 1 hour (both P < 0.0001), triglycerides at 2 hours (P < 0.0001), and glucose at 3 hours (P = 0.004); and all remained increased throughout the feed-challenge in all dogs. Postprandial urine cortisol/creatinine ratio was higher than fasting values (P = 0.001). Comparing between groups, there was an overall higher triglyceride response in overweight compared to lean (P = 0.001) and slightly overweight (P = 0.015) dogs. Overweight dogs also had higher fasting cortisol/creatinine ratio compared to lean dogs (P = 0.024). CONCLUSIONS AND CLINICAL IMPORTANCE: Postprandial responses of dogs to a high-fat mixed-meal were similar to those previously reported in people. The higher postprandial triglyceride response and fasting cortisol/creatinine ratio in the overweight dogs could be early signs of metabolic imbalance. Thus, although overweight dogs often appear healthy, metabolic alterations might be present.

Diagnostic and prognostic markers for uterine diseases in dogs.

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.

Increased concentrations of C-reactive protein but not high-mobility group box 1 in dogs with naturally occurring sepsis.

Sepsis is difficult to diagnose and remains a common mortality cause worldwide in both humans and animals. The uterine infection pyometra causes sepsis in more than half of affected dogs and therefore allows the natural physiological development of sepsis to be studied. To find a sepsis-specific biochemical marker that could be combined with conventional clinical criteria for a more robust and quick diagnosis of sepsis, we measured systemic concentrations of high-mobility group box 1 (HMGB1) in 23 healthy control dogs and in 27 dogs with pyometra, 74% of which had sepsis. We also measured concentrations of the major acute phase protein C-reactive protein (CRP) and an indicator for endotoxaemia, prostaglandin F2α metabolite (PGM) to assess the relative contribution of HMGB1 to the detection of systemic inflammation and endotoxaemia. We found that HMGB1 concentrations, in line with concentrations of CRP and PGM, were significantly increased in dogs with pyometra, and that concentrations of CRP, but not HMGB1, were significantly higher in dogs with sepsis compared to dogs without sepsis. Although serum HMGB1 did not differ between dogs with or without sepsis and was not correlated with either CRP or PGM concentrations, HMGB1 was correlated with the total white blood cell counts, suggesting an independent regulation and involvement in inflammation.

Intervertebral disc disease in dogs - part 1: a new histological grading scheme for classification of intervertebral disc degeneration in dogs.

Intervertebral disc (IVD) degeneration is common in dogs and can lead to serious disorders. Current treatments can relieve clinical signs of disease, but do not restore IVD function. The development of regenerative strategies for IVD dysfunction requires detailed knowledge of the pathogenesis of IVD degeneration and its underlying mechanisms. Histological examination of IVDs at different stages of degeneration might provide this knowledge, but as there is currently no histological grading scheme for canine IVD degeneration, the aim of this study, which is the first of a two-part series, was to design and validate an appropriate scheme. Three independent observers evaluated 35 IVDs at different stages of degeneration using the scheme. Glycosaminoglycan contents of the nucleus pulposus and macroscopic grading according to Thompson, which are considered 'gold standards' for IVD degeneration, were used to validate the scheme. Reproducibility was assessed by analysing the inter-observer reliability of all individual variables of the grading scheme, using a weighted κ analysis. Significant correlations were found between Thompson grading and total histological score (r=0.94; P<0.01) and between glycosaminoglycan content and total histological score (r=-0.72; P<0.01). Most individual histological variables showed 'moderate' to 'almost perfect' inter-observer reliability. The high correlation with the gold standards in combination with the high reproducibility indicates that the proposed histological grading scheme is reliable and objective for classification of IVD degeneration in both chondrodystrophic and non-chondrodystrophic dog breeds.

Elevation of serum thymidine kinase 1 in a bacterial infection: canine pyometra.

Pyometra is a bacterial infection of the uterus that is common in dogs and is potentially life-threatening if delayed in diagnosis and/or treatment. Thymidine kinase 1 (TK1) is a cytosolic enzyme involved in DNA precursor synthesis, and it is also present in serum from patients with malignant diseases. TK1 has been used as a cell proliferation biomarker for many years in human medicine and recently in dogs. However, little is known regarding serum TK1 levels in individuals with bacterial infection. The objective of this study was to determine the activity of serum TK1 in dogs with pyometra and compare it with hematologic and biochemical parameters, e.g., acute phase proteins and inflammatory mediators such as C-reactive protein and Prostaglandin F(2α). Serum and plasma TK1 activity of 40 healthy female dogs and 54 dogs with pyometra were analyzed using an optimized [(3)H]-thymidine phosphorylation assay. TK1 activities in serum or plasma were significantly higher in dogs with pyometra as compared with healthy female dogs (mean ± SD: 4.0 ± 7.3 pmol/min/mL in the pyometra group and 1.07 ± 0.34 pmol/min/mL in healthy control group). However, there was no difference in TK1 activity between systemic inflammatory response syndrome (SIRS) positive (n = 38) and SIRS negative (n = 16) pyometra cases. Furthermore, the plasma TK1 activity decreased in six and increased in one pyometra patients (n = 10), 24 h after ovariohysterectomy. No significant correlations (P > 0.05) were found between TK1 activity and hematological or other biochemical parameters. In conclusion, the TK1 activity was significantly elevated in dogs with pyometra. Further studies are needed to evaluate the mechanism and role of serum TK1 activity in bacterial infections and its possible diagnostic or prognostic value.

Clinical and molecular characteristics of pyometra in female dogs.

Pyometra is a common disease of female dogs. In Sweden, where approximately 90% of the dog population is intact (not neutered), nearly 25% of all female dogs are diagnosed with the disease before 10 years of age. In certain high-risk breeds, this risk of developing pyometra exceeds 50%. Various clinical signs associated with the genital tract as well as with systemic disease are present in dogs with pyometra. A frequent and serious consequence of the uterine infection is endotoxaemia and progression into the systemic inflammatory response syndrome (SIRS), or sepsis, and the disease is then regarded as a medical emergency. Acute phase proteins and inflammatory markers associated with SIRS and with the outcome as measured by length of hospitalization have been identified in blood samples. Recently, the inflammatory response in infected uterine tissue during pyometra has been more closely explored. The expression of many genes associated with chemokines, cytokines, inflammatory cell extravasation, anti-bacterial action, the complement system and innate immune responses and also a large panel of proteases are upregulated in the uterine tissue in pyometra. Products of certain upregulated genes may be detected systemically and used for diagnostic or prognostic purposes provided that tests are developed in the future. More knowledge of the complex local and systemic inflammatory response in pyometra may allow identification of novel disease biomarkers or future targets for treatment. In this article, clinical as well as molecular characteristics of the disease are reviewed.

Cytokines as immunological markers for systemic inflammation in dogs with pyometra.

Pyometra is a disease in dogs caused by bacterial infection of the uterus and resulting in SIRS (systemic inflammatory response syndrome) in nearly 6 of 10 cases. Clinical diagnostic criteria for SIRS are relatively unspecific, and biomarkers for the diagnosis of pyometra and SIRS in dogs are needed. Serum samples from 32 dogs were used in this study and grouped into dogs with pyometra and SIRS, dogs with pyometra without SIRS and healthy controls. The serum concentrations of IFN-γ, IL-4, IL-6, IL-7, IL-8, IL-10, IL-15, IL-18 and TNF-α were measured using multiplex analyses. The serum concentrations of CRP (C-reactive protein) were determined using sandwich ELISA. IL-7, IL-8, IL-15, IL-18 and TNF-α were detected in >94% of samples. IL-10 was detected in 28% of samples, and IL-4, IL-6 and IFN-γ were undetectable. Higher serum concentrations of IL-7 (p < 0.05) were detected in SIRS-positive dogs with pyometra (n = 13) as compared with healthy controls (n = 11). The concentrations of IL-8 were higher in SIRS-positive dogs with pyometra compared to the SIRS-negative group (n = 8; p < 0.05). Positive correlations of IL-15 with IL-18 (p < 0.0001) and with the concentrations of IL-7 (p < 0.0001 for both) were found, although there was no significant difference between groups. Furthermore, IL-15 correlated with concentrations of CRP (p < 0.05), which were higher in dogs with pyometra compared to controls (p < 0.0001). Our data suggest a role of several cytokines in the development of a systemic disease in dogs with pyometra and a possible diagnostic value for serum CRP, IL-7, IL-15 and IL-18 in canine SIRS caused by pyometra.

Breed variations in the incidence of pyometra and mammary tumours in Swedish dogs.

Dogs enrolled in a Swedish insurance company (during 1995-2006) were studied for development of pyometra and mammary tumours (MTs), with special attention to breed and age. There were over 260,000 female dogs with over 1,000,000 dog-years at risk (DYAR) in the database, using data on bitches up to 10 years of age and 110 breeds with over 1000 DYAR. In total, 20 423 bitches were diagnosed with pyometra and 11,758 with MTs and 30,131 with either or both of the two diseases. The incidence rate (IR) for pyometra was 199 (95% CI 196-202), for MTs 112 (95% CI 110-114) and for either or both of the two diseases 297 (95% CI 294-301) dogs per 10,000 DYAR. The mean age of diagnosis pyometra was 7.0 years (SD ± 2.2), MTs 8.0 years (SD ± 1.6). In all breeds, the overall proportion of the bitches that developed disease by 10 years of age was for pyometra 19%, MTs 13%, and either or both of two diseases 30%. The top 10 breeds diagnosed with either or both of the two diseases were the Leonberger (73%), Irish Wolfhound (69%), Bernese Mountain Dog (69%), Great Dane (68%), Staffordshire Bull Terrier (66%), Rottweiler (65%), Bullterrier (62%), Doberman (62%), Bouvier des Flandres (60%), Airdaleterrier (60%). These data provide information of the combined disease incidence in a large number of different breeds. Breed variations in incidence rate suggests genetic components in disease development. Our study may be valuable in the search for genetic risk-factors or protective factors.

Comparison of haemodynamic changes during two surgical methods for neutering female dogs.

The aim was to investigate if intraoperative registrations of blood pressure and heart rate could be used to estimate surgical trauma. In a prospective clinical trial, registrations in eight dogs neutered by laparoscopic ovariectomy (LOE) were compared with eight dogs subjected to open ovariohysterectomy (OHE). For comparisons phases were used: phase zero=steady state after induction of anaesthesia; phase one=opening of abdomen; phase two=severing of ovarian pedicles; and, phase three=abdominal closure. During LOE, mean systolic blood pressure increased by 7 mmHg (p=0.05) and 15 mmHg (p=0.01) from phase zero to phase one and two, respectively, and during OHE by 3 mmHg (ns) and 29 mmHg (p<0.0001), respectively. The increase from phase one to phase two differed between groups (p=0.03). Heart rate did not change. Frequent intraoperative measurements of blood pressure appear a promising method for evaluating surgical trauma.

Plasma PGF 2 alpha metabolite levels in cats with uterine disease.

Uterine disease induces PGF(2 alpha) increase in many animal species, which can be measured by the metabolite 15-keto-(13,14)-dihydro-PGF(2 alpha) (PGFM). Plasma PGFM levels are associated with severity of the uterine disease and presence of systemic inflammatory response syndrome (SIRS) in dogs. The objectives in this study were to investigate PGFM levels, presence of SIRS, and clinical and laboratory parameters in female cats as possible indicators for severity of uterine disease. In total, 7 female cats with pyometra, 2 with mucometra, 7 with cystic endometrial hyperplasia (CEH), and 14 healthy control cats were included. Physical examination, ovariohysterectomy, and histopathology were performed, laboratory parameters were analyzed, and PGFM levels were analyzed by radioimmunoassay. Analysis of variance, Fisher's exact test, Student's t-test and Pearson's product moment correlation coefficient were used for data analysis. In cats with pyometra, mean PGFM levels were increased (21.1 nmol L(-1)) but were decreased in cats with CEH (0.4 nmol L(-1)) compared with control cats (0.6 nmol L(-1)). In cats with mucometra, the mean PGFM level was 8.8 nmol L(-1). Systemic inflammatory response syndrome was present in 6 (85%) cats with pyometra, 1 cat with mucometra, and 1 cat with CEH. Hospitalization length was negatively correlated with albumin and positively correlated with total white blood cell count (WBC), neutrophils, band neutrophils (BN), percentage BN (PBN), and monocytes. Pyometra and mucometra were associated with increased plasma levels of PGFM. The parameters albumin, WBC, neutrophils, BN, PBN, and monocytes may be useful to determine morbidity as measured by hospitalization length.

Pyometra in bitches induces elevated plasma endotoxin and prostaglandin F2alpha metabolite levels.

Endotoxemia in bitches with pyometra can cause severe systemic effects directly or via the release of inflammatory mediators. Plasma endotoxin concentrations were measured in ten bitches suffering from pyometra with moderately to severely deteriorated general condition, and in nine bitches admitted to surgery for non-infectious reasons. Endotoxin samples were taken on five occasions before, during and after surgery. In addition, urine and uterine bacteriology was performed and hematological, blood biochemical parameters, prostaglandin F2alpha metabolite 15-ketodihydro-PGF2alpha (PG-metabolite), progesterone and oestradiol (E2-17beta) levels were analysed. The results confirm significantly increased plasma levels of endotoxin in bitches with pyometra and support previous reports of endotoxin involvement in the pathogenesis of the disease. Plasma concentrations of PG-metabolite were elevated in pyometra bitches and provide a good indicator of endotoxin release since the concentrations were significantly correlated to the endotoxin levels and many other hematological and chemistry parameters. The gamma-globulin serum protein electrophoresis fraction and analysis of PG-metabolite can be valuable in the diagnosis of endotoxin involvement if a reliable, rapid and cost-effective test for PG-metabolite analysis becomes readily available in the future. Treatment inhibiting prostaglandin biosynthesis and related compounds could be beneficial for bitches suffering from pyometra.

Differentiation between pyometra and cystic endometrial hyperplasia/mucometra in bitches by prostaglandin F2alpha metabolite analysis.

Bitches with pyometra are potential emergency cases which may be clinically difficult to differentiate from cases of cystic endometrial hyperplasia (CEH) in combination with mucometra. In the present study plasma prostaglandin F(2alpha), as measured by its main metabolite 15-keto-13,14-dihydro-PGF(2alpha) (PG-metabolite) concentrations, blood biochemical and hematological parameters were measured in 59 bitches with pyometra, 10 bitches with CEH and nine controls to determine if PG-metabolite could differentiate between the three uterine conditions. Bitches with pyometra had significantly higher plasma levels of PG-metabolite than bitches with CEH (P=0.002) and the controls (P=0.002). PG-metabolite analysis alone had a high sensitivity (98.3%) and a high specificity (80.0%) for the differentiation of pyometra versus CEH in bitches where fluid in the uterus was diagnosed. When a combination of PG-metabolite and percentage band neutrophils (PBN) was used for differentiation of the two diagnoses, a sensitivity of 100% and specificity of 90.0% was obtained. This means that the combination of PG-metabolite and PBN analysis allows for differentiation between cases of pyometra and CEH. If the PG-metabolite level in a bitch is >or=4,524 pmol l(-1), there is a 99% probability of the diagnosis pyometra versus CEH. Levels of PG-metabolite >or=3,054 pmol l(-1), >or=2,388 pmol l(-1) or>or=1,666 pmol l(-1) indicates a 95%, 90% or 80% probability of pyometra, respectively. At high PG-metabolite levels (above about 3,000 pmol l(-1)), PG-metabolite alone is enough for differentiation of pyometra versus CEH. The results of the present study showed that PG-metabolite analysis is valuable in the diagnosis and prediction of severity of uterine diseases.

Antimicrobial resistance in Escherichia coli isolated from bitches with pyometra and from urine samples from other dogs.

To assess whether the rates of antimicrobial susceptibility in bacteria isolated from the urine of dogs with urinary tract infections are similar to those of bacteria isolated from bitches with pyometra, the antimicrobial resistance of Escherichia coli isolated from the two groups were determined and compared. The samples were collected in Sweden between April 2002 and March 2003, and potential changes over time were assessed by comparing the results with corresponding data from 1991 to 1993. Among 80 isolates of E coli from cases of pyometra, the proportions that were resistant to the antimicrobials used in canine practice were generally low (ampicillin 10 per cent, enrofloxacin 4 per cent, gentamicin 0 per cent, streptomycin 5 per cent, sulfamethoxazole 8 per cent, tetracycline 4 per cent and trimethoprim 2 per cent) and similar to the proportions reported previously. Significantly lower proportions of resistance were recorded among the pyometra isolates than among 92 isolates from urine samples submitted by animal hospitals to ampicillin (P=0.04), streptomycin (P=0.002) and tetracycline (P=0.03), but there were no differences between the pyometra isolates and 113 isolates from urine samples submitted by animal clinics.

Breed risk of pyometra in insured dogs in Sweden.

An animal insurance database containing data on over 200,000 dogs was used to study the occurrence of pyometra with respect to breed and age during 1995 and 1996 in Swedish bitches <10 years of age. A total of 1,803 females in 1995 and 1,754 females in 1996 had claims submitted because of pyometra. Thirty breeds with at least 800 bitches insured each year were studied using univariate and multivariate methods. The crude 12-month risk of pyometra for females <10 years of age was 2.0% (95% confidence interval = 1.9-2.1%) in 1995 and 1.9% (1.8-2.0%) in 1996. The occurrence of pyometra differed with age, breed, and geographic location. The risk of developing pyometra was increased (identified using multivariate models) in rough Collies, Rottweilers, Cavalier King Charles Spaniels, Golden Retrievers, Bernese Mountain Dogs, and English Cocker Spaniels compared with baseline (all other breeds, including mixed breed dogs). Breeds with a low risk of developing the disease were Drevers, German Shepherd Dogs, Miniature Dachshunds, Dachshunds (normal size), and Swedish Hounds. Survival rates indicate that on average 23-24% of the bitches in the databases will have experienced pyometra by 10 years of age. In the studied breeds, this proportion ranged between 10 and 54%. Pyometra is a clinically relevant problem in intact bitches, and differences related to breed and age should be taken into account in studies of this disease.