Effect of blood handling conditions on progesterone assay results obtained by chemiluminescence in the bitch

Evidence-based practice in canine artificial insemination

A number of methods are currently used to predict the optimal date of insemination of the breeding bitch, particularly with the use of frozen-thawed canine semen which has a far shorter lifespan than fresh semen. Aside from confirming cytological oestrus, vaginal cytology is of no assistance in predicting the most fertile day(s) in a bitch; however, a neglected avenue of research suggests that vaginal cytology may be of great importance in confirming the days of optimal fertility retrospectively. Similarly, vaginoscopy provides clues as to the stage of a bitch's cycle but is inadequate as a sole determinant of her most fertile days. Nevertheless, vaginoscopy is useful to identify very late oestrus and the onset of dioestrus, as well as Stage I of labour (cervical dilatation). Due to variations in the rate at which circulating progesterone concentrations rise in individual bitches, the reliability of circulating progesterone concentrations for determining the optimal day(s) of insemination with frozen-thawed semen decreases as values rise. Moreover, progesterone assay results can vary widely due to extrinsic factors such as the time of blood sampling, sample storage conditions and the assay employed. Finally, this review investigates evidence surrounding various insemination routes and suggests that well-performed vaginal insemination, even with frozen-thawed semen, may be an acceptable approach for cases where transcervical insemination is impractical.

Does Placental Efficiency and Vascularization Affect Puppy Health? A Study in Boxer and Dobermann Dogs

BACKGROUND

The anatomical and functional characteristics of the placenta influence the adaptive ability of the fetus to the extrauterine environment. Placental efficiency, measured as the gram of neonate produced by each gram of placenta, summarizes these characteristics. In the present study, placental efficiency and its impact on the 7-day postpartum life of the puppies were studied in canine large breeds.

METHODS

Placental efficiency (PE) was computed using chorioallantois weight (WPE) and surface (SPE) efficiency for puppies born from natural delivery or elective cesarean section. Capillary density was also histologically determined. Neonate viability was estimated by the APGAR score and the daily weight gain (DWG) was recorded on day 7 after delivery.

RESULTS

from 15 large-breed bitches, 69 live puppies were born by natural delivery (24 puppies) and elective cesarean section (45 puppies). Cluster analysis detected a group of neonates for which reduced placental efficiency (8 for the WPE, 9 for the SPE) was identified, despite a placental weight and surface within the mean and no difference in capillary density. In this group, the DWG was lower and the mortality within 7 days was higher.

CONCLUSIONS

the results suggest that placental efficiency could be an additional tool for the evaluation of a puppy in the first 7 days after delivery.

A Precision Assessment of a Point-of-Care Immunological Analyzer for Swift Progesterone Measurement and Guidance for Determining the Optimal Breeding Time in Bitches

The measurement of serum progesterone often varies due to different laboratory methodologies and individual canine characteristics. In this investigation, serum progesterone outcomes obtained from a commercial point-of-care immunological analyzer, designed for efficient serum progesterone assessment in bitches, were compared with results derived from chemiluminescent microparticle immunoassay from reference laboratories in Thailand. Our thorough documentation encompassed various parameters: mean, standard deviation, 95% confidence interval, and minimum and maximum serum progesterone concentration values. Additionally, we meticulously recorded the Pearson's correlation coefficient, Lin's concordance correlation coefficient, and the bias correction factor. Interestingly, there was no significant difference (p > 0.05) in the means obtained by the point-of-care immunological analyzer and chemiluminescent microparticle immunoassay. The Pearson's correlation coefficient between the point-of-care immunological analyzer and chemiluminescent microparticle immunoassay stood at 0.957, with Lin's concordance correlation coefficient for point-of-care immunological analyzer recorded as 0.949. Furthermore, the bias correction factor was established at 0.991. This investigation followed established chemiluminescent microparticle immunoassay guidelines, modified to incorporate the mean and 95% confidence interval as criteria for optimal breeding time using the point-of-care immunological analyzer. In conclusion, the commercial point-of-care immunological analyzer emerges as a valuable tool, aiding in precisely determining the optimal timing for natural mating or artificial insemination in bitches.

Progesterone Analysis in Canine Breeding Management

Progesterone is a worthwhile addition to the clinical assessment of cycle stage for breeding, elective cesarian delivery, and reproductive management in the bitch if reliably measured. Clinical decisions based on systemic progesterone concentrations also require the rapid return of results. Most commercially accessible analyses capable of returning results within a day still rely primarily on immunoassays of one kind or another. Point-of-care instruments utilizing similar technology have been developed more recently to enable results to be generated in-house. Repeated monitoring of progesterone on whatever platform can be useful if consistent collection and analysis protocols ensure acceptable precision, accuracy, and repeatability.

Validation of a dry-slide immunoassay for progesterone analysis in canine plasma in a clinical setting

BACKGROUND

The identification of canine ovulation is critical for successful breeding. Progesterone measurements are useful for identifying ovulation. Progesterone assays are also quantitative and easily accessed, making them valuable in veterinary practice.

OBJECTIVES

We aimed to validate a dry-slide immunoassay (DSI) for use in dogs, including a method comparison with the chemiluminescence assay (CLIA) and mass spectrometry.

METHODS

Twenty-nine bitches were prospectively recruited. Accuracy, precision, interference, and stability were evaluated. Method comparison between DSI and CLIA and mass spectrometry was conducted, and bias was calculated.

RESULTS

Repeatability was 8.0%-10.8%, and within-laboratory imprecision was 8.8%-11.1% for four concentration levels. Recovery under dilution was 61%-100%, and the method was linear to a concentration of ~50 nmol/L. Recovery after the addition of a high progesterone sample was 76%-83%. Minor changes were seen in one hemolytic and two lipemic samples. Storage at room temperature for 12-24 hours resulted in concentrations that were 57%-96% of the initial concentrations. For samples frozen at -80°C, the concentrations were reduced 17%-27%. There was a significant difference between results from the DSI and CLIA, and a proportional bias was seen when DSI was compared with mass spectrometry, where CLIA correlated better than DSI.

CONCLUSIONS

Precision and accuracy were acceptable. A proportional bias was seen between DSI and CLIA. A small amount of interference was seen with hemolysis and lipemia. Progesterone concentrations were decreased in samples stored at room temperature and -80°C. The results support the use of the DSI for ovulation timing but not for artificial insemination with frozen semen since progesterone concentrations might exceed the assay's linearity and precision limits.

Comparison of a Point-of-Care Analyzer With a Chemiluminescent Immunoassay for Serum Progesterone Measurement in Breeding Management of the Bitch

Accurate serum progesterone measurements for timing bitches during breeding management is critical for reproductive practice, especially as artificial insemination has become routine to facilitate breeding of animals that are geographically or temporally separated. To measure serum progesterone, chemiluminescent immunoassay (CLIA) has replaced radioimmunoassay as the current standard in the bitch due to its high correlation and increased practicality. In January 2019, a colorimetric point-of-care (POC) immunoassay for quantitative in-clinic canine serum progesterone measurements in <30 min was released. This study provides an independent comparison of the POC (Catalyst One, IDEXX) to the current industry standard, CLIA (Immulite-2000, Siemens). To assess inter-assay imprecision of POC and agreement of the POC and CLIA results, 100 canine serum samples were analyzed on three analyzers (POC-1, POC-2, and CLIA), of which, 74 (POC-1) and 75 (POC-2) results were within POCs' reportable range of 0.2–20 ng/mL and included in the study. To assess intra-assay imprecision, pooled canine serum samples at low (L1), intermediate (L2), and high (L3) progesterone concentrations were analyzed ten times each on POC-1 and CLIA. Relative to CLIA, POC values showed good correlation (POC-1, r² = 0.9366; POC-2, r² = 0.9438, P < 0.0001) and significant positive proportional bias at values >2 ng/mL. The POC inter-assay coefficients of variation (CVs) were 13.2% (0.2–2.9 ng/mL, 0.6–9.2 nmol/L, L1), 10.0% (3.0–9.9 ng/mL, 9.5–31.5 nmol/L, L2), 7.1% (10.0–20.0 ng/mL, 31.8–63.6 nmol/L, L3), and 11.2% (all samples). The intra-assay CVs for POC (L1, 15.3%; L2, 7.0%; L3, 4.7%) were higher than those for CLIA (L1, 5.89%; L2, 4.89%; L3, 3.44%). Based on the more rapid increase in serial serum progesterone concentrations in ovulating bitches and the greater imprecision of the POC, the clinical interpretations of serum progesterone measurements as they relate to canine breeding management should be made with caution.

Evaluation of surface plasmon field-enhanced fluorescence spectroscopy for rapid measurement of progesterone concentration in bitches

OBJECTIVE

To compare progesterone (P4) concentrations measured with surface plasmon field-enhanced fluorescence spectroscopy (SPFS) and chemiluminescence immunoassay (CLIA) in serum and plasma samples of client-owned bitches of various ages and breeds and to determine reference ranges for P4 concentrations at various stages of the estrous cycle.

SAMPLES

102 serum samples and 104 plasma samples.

PROCEDURES

In experiment 1, 1 aliquot each of serum and plasma was analyzed for P4 concentration by use of SPFS incorporated in a veterinary-specific point-of-care immunologic analyzer and CLIA. In experiment 2, serum collected from bitches in various stages of the estrous cycle was analyzed for P4 concentration by use of SPFS to establish reference ranges for each stage.

RESULTS

In experiment 1, P4 concentrations measured by SPFS and CLIA were highly correlated (serum, r = 0.966; plasma, r = 0.968). In experiment 2, ranges of serum basal (proestrous) P4 concentrations (n = 114) and P4 concentrations at the estimated time of ovulation (76), during pregnancy or diestrus (107), and during the prepartum period (50) measured with SPFS were 0.42 to 1.46 ng/mL, 3.69 to 7.85 ng/mL, 11.73 to 28.24 ng/mL, and 1.54 to 3.22 ng/mL, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

Because serum and plasma P4 concentrations measured with SPFS were highly correlated with those measured with CLIA and ranges of serum P4 concentrations measured with SPFS for each of phase of the estrous cycle were well-defined for the large sample size, veterinarians may be able to accurately use this veterinary-specific point-of-care immunologic analyzer with SPFS methodology to determine P4 concentrations of bitches in their daily practice.

Evaluation of two chemiluminescent assays compared with radioimmunoassay for serum progesterone measurement in bitches

Serum progesterone (sP4) measurement is commonly used to determine the optimal time for mating in bitches, and to diagnose reproduction-related abnormalities. Radioimmunoassay (RIA) is the gold standard assay, but is becoming less available, and has several practical disadvantages. Chemiluminescence immunoassays (CLIA) are commonly used in human medicine for sP4 measurement, and are becoming more available in veterinary medicine. Our objective was to compare the sP4 results obtained by RIA and two CLIA systems (Immulite-Siemens [IS-CLIA] and Elecsys-Roche [ER-CLIA]) in the same sera in 60 client-owned healthy bitches at different estrous cycle stages. The agreement between the two CLIAs and RIA was examined using the Passing-Bablok regression and Bland Altman plots. Comparing sP4 concentrations measured by the IS-CLIA to the RIA yielded an intercept of 0.16 ng/mL (95% confidence interval [95%CI], 0.03-0.25) with a slope of 0.45 (95%CI, 0.44-0.47) and a median difference of -2.10 ng/mL (P < 0.0001) that was strongly correlated to the average of measurements (r = -0.97; P < 0.0001). Comparing sP4 concentrations measured by the ER-CLIA to the RIA yielded an intercept of -0.23 ng/mL (95%CI, -0.56 to -0.09) with a slope of 1.06 (95%CI, 1.00-1.12) and a median difference of -0.09 ng/mL (P = 0.9), that was weakly correlated to the average of measurements (r = 0.34; P = 0.018). The performance of the ER-CLIA was similar to the RIA, while the IS-CLIA showed significantly different results compared to the RIA. Our study supports the conclusion that sP4 results generated by the ER-CLIA can be used interchangeably with RIA results for clinical purposes, while IS-CLIA results require adjustment to RIA results for clinical practice.

The validation of a commercial enzyme-linked immunosorbent assay and the effect of freeze-thaw cycles of serum on the stability of cortisol and testosterone concentrations in Aceh cattle

Background: To obtain accurate measurements of cortisol (C) and testosterone (T) in Aceh cattle, commercial enzyme-linked immunosorbent assay (ELISA) kits need to be carefully validated. Moreover, repeated freeze-thaw cycles during the storage of the samples may affect the stability of the hormones in the serum. Here, the reliability of C and T concentration measurements in the serum of Aceh cattle, was tested using commercial C and T ELISA kits designed to measure human C and T concentrations. Further, the effect of repeated freeze-thaw cycles on the stability of C and T concentrations in the serum was evaluated. Methods: Commercial C (Cat. no. EIA-1887) and T (Cat. no. EIA-1559) ELISA kits from DRG Instruments GmbH were validated through an analytical validation test (i.e., parallelism, accuracy, and precision) and a biological validation test (for C: effect of transportation on the C secretion; for T: the concentrations of T between bulls and cows). To test the effects of freeze-thaw cycles, cattle serum was subjected to the following treatments: (i) remained frozen at -20 OC (control group); (ii) exposed to freeze-thaw cycles for two, four, six, and eight times (test groups).   Results: Parallelism, accuracy, and precision tests showed that both  C and T ELISA kits adequately measured C and T in the serum of Aceh cattle. Concentrations of C post-transportation were significantly higher than pre-transportation (p<0.01). Concentrations of T in bulls were significantly higher than in cows (p<0.01). After four to eight freeze-thaw cycles, C concentrations were significantly lower compared to the control group (all p < 0.05). In contrast, T concentrations remained stable (all p>0.05). Conclusions: Commercial C (EIA-1887) and T (EIA-1559) ELISA kits are reliable assays for measuring serum C and T, respectively, in Aceh cattle. Repeated freeze-thaw cycles significantly affected the stability of serum C, but did not for T.

The validation of a commercial enzyme-linked immunosorbent assay and the effect of freeze-thaw cycles of serum on the stability of cortisol and testosterone concentrations in Aceh cattle

Background: To obtain accurate measurements of cortisol (C) and testosterone (T) in Aceh cattle, commercial enzyme-linked immunosorbent assay (ELISA) kits need to be carefully validated. Moreover, repeated freeze-thaw cycles during the storage of the samples may affect the stability of the hormones in the serum. Here, the reliability of C and T concentration measurements in the serum of Aceh cattle, was tested using commercial C and T ELISA kits designed to measure human C and T concentrations. Further, the effect of repeated freeze-thaw cycles on the stability of C and T concentrations in the serum was evaluated. Methods: Commercial C (Cat. no. EIA-1887) and T (Cat. no. EIA-1559) ELISA kits from DRG Instruments GmbH were validated through an analytical validation test (i.e., parallelism, accuracy, and precision) and a biological validation test (for C: effect of transportation on the C secretion; for T: the concentrations of T between bulls and cows). To test the effects of freeze-thaw cycles, cattle serum was subjected to the following treatments: (i) remained frozen at -20 OC (control group); (ii) exposed to freeze-thaw cycles for two, four, six, and eight times (test groups).   Results: Parallelism, accuracy, and precision tests showed that both  C and T ELISA kits adequately measured C and T in the serum of Aceh cattle. Concentrations of C post-transportation were significantly higher than pre-transportation (p<0.01). Concentrations of T in bulls were significantly higher than in cows (p<0.01). After four to eight freeze-thaw cycles, C concentrations were significantly lower compared to the control group (all p < 0.05). In contrast, T concentrations remained stable (all p>0.05). Conclusions: Commercial C (EIA-1887) and T (EIA-1559) ELISA kits are reliable assays for measuring serum C and T, respectively, in Aceh cattle. Repeated freeze-thaw cycles significantly affected the stability of serum C, but did not for T.

The validation of a commercial enzyme-linked immunosorbent assay and the effect of freeze-thaw cycles of serum on the stability of cortisol and testosterone concentrations in Aceh cattle

Background: To obtain accurate measurements of cortisol (C) and testosterone (T) in Aceh cattle, commercial enzyme-linked immunosorbent assay (ELISA) kits need to be carefully validated. Moreover, repeated freeze-thaw cycles during the storage of the samples may affect the stability of the hormones in the serum. Here, the reliability of C and T concentration measurements in the serum of Aceh cattle, was tested using commercial C and T ELISA kits designed to measure human C and T concentrations. Further, the effect of repeated freeze-thaw cycles on the stability of C and T concentrations in the serum was evaluated. Methods: Commercial C (Cat. no. EIA-1887) and T (Cat. no. EIA-1559) ELISA kits from DRG Instruments GmbH were validated through an analytical validation test (i.e., parallelism, accuracy, and precision) and a biological validation test (for C: effect of transportation on the C secretion; for T: the concentrations of T between bulls and cows). To test the effects of freeze-thaw cycles, cattle serum was subjected to the following treatments: (i) remained frozen at -20 ^OC (control group); (ii) exposed to freeze-thaw cycles for two, four, six, and eight times (test groups).   Results: Parallelism, accuracy, and precision tests showed that both  C and T ELISA kits adequately measured C and T in the serum of Aceh cattle. Concentrations of C post-transportation were significantly higher than pre-transportation (p<0.01). Concentrations of T in bulls were significantly higher than in cows (p<0.01). After four to eight freeze-thaw cycles, C concentrations were significantly lower compared to the control group (all p < 0.05). In contrast, T concentrations remained stable (all p>0.05). Conclusions: Commercial C (EIA-1887) and T (EIA-1559) ELISA kits are reliable assays for measuring serum C and T, respectively, in Aceh cattle. Repeated freeze-thaw cycles significantly affected the stability of serum C, but did not for T.

Effect of time and temperature on stability of progestagens, testosterone and cortisol in Asian elephant blood stored with and without anticoagulant

The value of biological samples collected in the field is compromised if storage conditions result in analyte degradation, especially in warmer climates like Thailand. We evaluated the effects of time and temperature on immunoactive steroid hormone stability in Asian elephant (Elephas maximus) blood stored with and without an anti-coagulant before centrifugation. For each elephant (5 male, 5 female), whole blood was aliquoted (n = 2 ml each) into 13 red top (without anticoagulant) or purple top (with anticoagulant) tubes. One tube from each treatment was centrifuged immediately and the serum or plasma frozen at -20°C (Time 0, T0). The remaining 12 aliquots were divided into stored temperature groups: 4°C, room temperature (RT, ~22°C), and 37°C, and centrifuged after 6, 24, 48 and 62 h of storage. Serum and plasma concentrations of progestagens in females, testosterone in males and cortisol in both sexes were quantified by validated enzyme immunoassays. Steroid concentration differences from T0 were determined by a randomized complete block ANOVA and Dunnett's tests. The only evidence of hormone degradation was cortisol and testosterone concentrations in serum stored at 37°C. Testosterone concentrations declined by 34% at 48 h and 52% at 62 h, cortisol was decreased by 19% after 48 h and 27% after 62 h at 37°C, respectively. None of the other aliquots displayed significant changes over time at any temperature. In conclusion, steroids appear to be stable in blood for nearly 3 days at room or refrigeration temperatures before centrifugation; steroids in samples with ethylenediaminetetraacetic acid were particularly stable. However, warmer temperatures may negatively affect steroids stored without anti-coagulant, perhaps due to red blood cell metabolism. Thus, under field conditions with no access to cold or freezer temperatures, collection of plasma is a better choice for elephants up to at least 62 h before centrifugation.

Blood periovulatory progesterone quantification using different techniques in the dog

Blood progesterone concentration is used in several procedures related to the reproduction in the bitch, such as ovulation monitoring, estimating time of parturition, or hypo-luteoidism management. Several techniques are available to evaluate blood progesterone concentration, such as the radioimmunoassay (RIA), the chemiluminescent immunoassay (CLIA), and the enzyme-linked immunosorbent assay (ELISA). The aim of this study was to compare the blood progesterone concentration using these three methods during the periovulatory period of 23 bitches. Vaginal cytology was used to classify cytologic estrus (CE) and cytologic diestrus (CD), and blood samples were collected once during proestrus and every other day between CE and CD. The samples were retrospectively classified in the different phases of the estrus based on CD. Pregnancy rate and gestational length were also recorded. A significant increase of the circulating progesterone during the progression of the estrus was recorded, and there were significant differences in the values when using the different methods, with lesser, intermediate, and greatest values with use of the RIA, CLIA, and ELISA, respectively. There was a high correlation (Pearson's correlation coefficient = 0.978) and substantial strength-of-agreement (Lin's concordance correlation coefficient = 0.966) between values obtained when using CLIA and RIA, while there was a high correlation (Pearson's correlation coefficient = 0.955) but poor strength-of-agreement (Lin's concordance correlation coefficient = 0.866) with use of the ELISA and RIA. The data reported in this study provide evidence that the method used for measuring the blood progesterone concentration during the periovulatory phase of the bitch significantly affected the progesterone values.

Evaluation der mittels Chemilumineszenztest gemessenen Blut-Progesteronkonzentration bei der Hündin am Tag der Ovulation

Gegenstand und Ziel: Durch den Hersteller vorgenommene Änderungen von Testsystemen, die in der Veterinärmedizin zur Bestimmung von Hormonkonzentrationen eingesetzt werden, können eine Anpassung von Referenzbereichen notwendig machen. Material und Methode: Es erfolgten Vergleichsmessungen mit einem ursprünglich verwendeten und 2012 veränderten Chemilumineszenz-Testsystem zur Progesteronmessung. Zudem wurden interne und externe Qualitätskontrollen vor dem Hintergrund der Änderung des Tests ausgewertet. Ferner wurde mit dem veränderten Testsystem die Progesteronkonzentration bei Hündinnen zum Zeitpunkt der sonographisch verifizierten Ovulation gemessen, um die Referenzwerte bezüglich ihrer Eignung für die Ovulationsbestimmung zu überprüfen. Ergebnisse: In einem Konzentrationsbereich von 0–6 ng/ml ergab die Messung mit der veränderten Testcharge deutlich niedrigere Progesteronkonzentrationen als der ursprünglich gelieferte Test. Nationale und internationale Kontrollen zeigten aber, dass die mit dem abgeänderten Test verfahren gemessenen Progesteronwerte laborübergreifend eine gute Vergleichbarkeit aufweisen. Die mittlere Progesteronkonzentration zum Zeitpunkt der sonographisch detektierten Ovulation betrug 3,4 ± 0,9 ng/ml (2,0–4,5 ng/ml, n = 7 Hündinnen). Schlussfolgerung: Der als Indikator für den Ovulationszeitpunkt und zur Festlegung des Decktermins vormals weit verbreitete Progesteronbereich von 5–8 ng/ml musste auf ∼ 3,5 ng/ml angeglichen werden. Dieser Fall zeigt, dass regelmäßige Referenzwertevaluationen gerade in der veterinärmedizinischen Endokrinologie unumgänglich sind und zur guten Laborpraxis gehören. Der hier vorgestellte Referenzwert ist laborspezifisch und sollte in anderen Laboren, die mit demselben Testsystem arbeiten, vor der Verwendung validiert werden. Klinische Relevanz: Die Grenzwerte zur Beurteilung des Ovulationszeitpunkts der Hündin sollten vom Labor zur Verfügung gestellt werden. Von einer Beurteilung der Werte im Vergleich zu Literaturdaten wird dringend abgeraten.

Laboratory and Clinical Evaluation of a Feia Method for Canine Serum Progesterone Assay

The evaluation of progesterone (P4) concentration is a valuable tool in assessing physiological reproductive events and reproductive disorders in bitches. A reliable and rapid (preferable, point of care) determination of P4 is advisable in most cases. Aims of this study were to evaluate a fluorescence enzyme immunoassay (FEIA) for canine serum P4 concentration by (i) the agreement with liquid chromatography-tandem mass spectrometry (LC/MS/MS), (ii) the association with vaginal cytology and (iii) the accuracy in the prediction of the parturition date calculated from the estimated day of ovulation. Serum samples were collected from client-owned bitches presented between 2011 and 2014 for the evaluation of their oestrous cycle, pregnancy or reproductive disorders. The agreement between FEIA and LC/MS/MS, evaluated on 19 samples, was statistically significant (R(2) = 95.7%, p < 0.001), although FEIA showed significantly higher values than LC/MS/MS (p < 0.05). In the different phases of oestrous cycle, as determined by vaginal cytology, P4 concentrations (by FEIA) were statistically different (p < 0.05): anoestrus (n = 7) 0.38 ± 0.14 ng/ml, proestrus (n = 14) 1.04 ± 0.67 ng/ml and oestrus (n = 72) 6.8 ± 7.26 ng/ml. Mean pregnancy length from the estimated day of ovulation was 62.9 ± 1.8 days. In 13 of 22 (59.1%), 19 of 22 (86.3%) and 21 of 22 (95.5%) bitches pregnancy lasted 63 ± 1, 63 ± 2 and 63 ± 3 days, respectively. Three pregnancies were outside the 61-65 days range (60, 60 and 67 days). In conclusion, the FEIA method employed can be considered reliable and, in association with vaginal cytology, effective in evaluating the canine oestrous cycle.

Molecular Expression Profile Reveals Potential Biomarkers and Therapeutic Targets in Canine Endometrial Lesions

Cystic endometrial hyperplasia (CEH), mucometra, and pyometra are common uterine diseases in intact dogs, with pyometra being a life threatening disease. This study aimed to determine the gene expression profile of these lesions and potential biomarkers for closed-cervix pyometra, the most severe condition. Total RNA was extracted from 69 fresh endometrium samples collected from 21 healthy female dogs during diestrus, 16 CEH, 15 mucometra and 17 pyometra (eight open and nine closed-cervixes). Global gene expression was detected using the Affymetrix Canine Gene 1.0 ST Array. Unsupervised analysis revealed two clusters, one mainly composed of diestrus and CEH samples and the other by 12/15 mucometra and all pyometra samples. When comparing pyometra with other groups, 189 differentially expressed genes were detected. SLPI, PTGS2/COX2, MMP1, S100A8, S100A9 and IL8 were among the top up-regulated genes detected in pyometra, further confirmed by external expression data. Notably, a particular molecular profile in pyometra from animals previously treated with exogenous progesterone compounds was observed in comparison with pyometra from untreated dogs as well as with other groups irrespective of exogenous hormone treatment status. In addition to S100A8 and S100A9 genes, overexpression of the inflammatory cytokines IL1B, TNF and IL6 as well as LTF were detected in the pyometra from treated animals. Interestingly, closed pyometra was more frequently detected in treated dogs (64% versus 33%), with IL1B, TNF, LBP and CXCL10 among the most relevant overexpressed genes. This molecular signature associated with potential biomarkers and therapeutic targets, such as CXCL10 and COX2, should guide future clinical studies. Based on the gene expression profile we suggested that pyometra from progesterone treated dogs is a distinct molecular entity.