Comparison of radioimmunoassay and chemiluminescent assay methods to estimate canine blood cortisol concentrations

Spirostrain-Accelerated Chemiexcitation of Dioxetanes Yields Unprecedented Detection Sensitivity in Chemiluminescence Bioassays

Chemiluminescence is a fascinating phenomenon that involves the generation of light through chemical reactions. The light emission from adamantyl-phenoxy-1,2-dioxetanes can glow from minutes to hours depending on the specific substituent present on the dioxetane molecule. In order to improve the light emission properties produced by these chemiluminescent luminophores, it is necessary to induce the chemiexcitation rate to a flash mode, wherein the bulk of light is emitted instantly rather than slowly over time. We report the realization of this goal through the incorporation of spirostrain release into the decomposition of 1,2-dioxetane luminophores. DFT computational simulations provided support for the hypothesis that the spiro-cyclobutyl substituent accelerates chemiexcitation as compared to the unstrained adamantyl substituent. Spiro-linking of cyclobutane and oxetane units led to greater than 100-fold and 1000-fold emission enhancement, respectively. This accelerated chemiexcitation rate increases the detection sensitivity for known chemiluminescent probes to the highest signal-to-noise ratio documented to date. A turn-ON probe, containing a spiro-cyclobutyl unit, for detecting the enzyme β-galactosidase exhibited a limit of detection value that is 125-fold more sensitive than that for the previously described adamantyl analogue. This probe was also able to instantly detect and image β-gal activity with enhanced sensitivity in E. coli bacterial assays.

Assessment of a compounded synthetic adrenocorticotropic hormone product in 17 healthy dogs

OBJECTIVES

Synthetic adrenocorticotropic hormone or tetracosactide is routinely used in the diagnosis of hypoadrenocorticism and frequently in the diagnosis and treatment of hyperadrenocorticism. There have been repeated shortages of tetracosactide in recent years in Australia. This study investigated the agreement of serum cortisol after a compounded tetracosactide (Bova Aus), compared to commercial tetracosactide (Synacthen®) in healthy dogs.

METHODS

Prospective crossover study using 20 dogs. Ten dogs received 5 μg/kg Synacthen® on day 1 and 5 μg/kg compounded tetracosactide on Day 2. The other 10 dogs received the reverse order. Cortisol concentrations in each dog 1 h after injection were compared for agreement, which was defined as the limits of agreement of the Bland-Altman ratio to be within a range of 0.8-1.25. Passing-Bablok regression analysis examined for constant and proportional biases.

RESULTS

Three dogs were excluded with post-stimulation serum cortisol concentrations markedly outside reference interval. For the remaining 17 dogs, Bland-Altman ratio analysis of cortisol concentration (tetracosactide/Synacthen®) at 1 h found virtually no constant bias (mean of ratios 1.01;95% CI 0.97-1.05) and 95% limits of agreement were 0.88 (95% CI 0.78-0.90) and 1.17 (95% CI 1.13-1.25). This met our criteria for agreement between cortisol concentrations. Bias of the Bland-Altman difference was 2.8 nmol/L (95% CI -7.2 to 12.8); 95% limits of agreement -35.2 nmol/L (95% CI -57.0 to -26.1) and 40.8 nmol/L (95% CI 31.7-62.6). Passing-Bablok regression analysis did not identify bias.

CONCLUSION

In healthy dogs, cortisol concentrations were in agreement after compounded tetracosactide compared to commercial tetracosactide, Synacthen®.

Effects of EDTA on chemiluminescent immunoassay measurement of ACTH, cortisol, and thyroid hormones in dogs

When measuring blood hormones, pre-analytical sample handling can impact the quality of the results. Previous studies have shown improved stability of canine cortisol in ethylenediaminetetraacetic acid (EDTA) plasma compared to serum and interchangeability of serum and plasma when cortisol is measured by radioimmunoassay. Additionally, cortisol samples were also interchangeable when measured by chemiluminescent immunoassay if the EDTA concentration was consistent with that of optimally filled tubes, whereas excess EDTA interfered with the measurement of cortisol and serum and EDTA plasma were not interchangeable when measuring total thyroxine (TT4). The main limitation of these studies was that they were performed by spiking pooled serum samples with EDTA or in previously collected blood samples submitted to a clinical pathology laboratory. The purpose of the present study was to evaluate the effect of EDTA on the measurement of adrenocorticotropic hormone (ACTH), cortisol, TT4, free thyroxine (FT4), and thyroid stimulating hormone (TSH) in healthy dogs using the Siemens IMMULITE 1000. Whole blood from forty dogs was aliquoted into three Monoject sample tubes: no additive, completely filled EDTA tube, and 50% filled EDTA tube. Handling and storage conditions were identical, and all samples were analyzed on the same day. Bland-Altman plots and Passing-Bablok regression were used to assess agreement and risks for error, respectively. Proportional errors were found between serum and plasma samples for ACTH, cortisol, TT4, FT4, and TSH; systematic errors were also found for FT4. There was poor agreement and clinically significant differences between the measured concentrations of all hormones in serum and plasma, proving that these sample types are not interchangeable. Incompletely filled EDTA tubes were associated with significantly lower ACTH concentrations compared to completely filled EDTA tubes. When measured by chemiluminescent immunoassays that utilize alkaline phosphatase at the reporter enzyme, serum should be used for cortisol, TT4, FT4, and TSH, while plasma from completely filled EDTA tubes should be used for ACTH.

Validation study of canine serum cortisol measurement with the Immulite 2000 Xpi cortisol immunoassay

We report the results of validation of canine serum cortisol determination with the Immulite 2000 Xpi cortisol immunoassay (Siemens), with characterization of precision (CV), accuracy (spiking-recovery [SR] bias), and observed total error (TEo = bias + 2CV) across the reportable range, specifically at the most common interpretation thresholds for dynamic testing. Imprecision increased at increasing rate with decreasing serum cortisol concentration and bias was low, resulting in increasing TEo with decreasing serum cortisol concentration. Inter-laboratory comparison study allowed for determination of range-based bias (RB) and average bias (AB). At 38.6 and 552 nmol/L (1.4 and 20 μg/dL), between-run CV was 10% and 7.5%, respectively, and TEo ~30% and ~20%, respectively (TEo remained similar regardless of the considered bias: SR, RB, or AB). These analytical performance parameters should be considered in the interpretation of results and for future expert consensus discussions to determine recommendations for allowable total error (TEa). Importantly, the commonly used thresholds for interpretation of results were determined ~40 y ago with different methods of measurements and computation, hence updating is desirable. Quality control material (QCM) had between-run imprecision of 4% for QCM1 and 7% for QCM2; the bias was minimal for both levels. Acceptable QC rules are heavily dependent on the desired TEa for the QCM system (TEaQCM), itself limited by the desired clinical TEa. At low TEaQCM (20-33%), almost no rules were acceptable, whereas at high TEaQCM (50%), almost all rules were acceptable; further investigation is needed to determine which TEaQCM can be guaranteed by simple QC rules.

Methods for Pain Assessment in Calves and Their Use for the Evaluation of Pain during Different Procedures-A Review

The evaluation and assessment of the level of pain calves are experiencing is important, as the experience of pain (e.g., due to routine husbandry procedures) severely affects the welfare of calves. Studies about the recognition of pain in calves, and especially pain management during and after common procedures, such as castration, dehorning, and disbudding, have been published. This narrative review discusses and summarizes the existing literature about methods for pain assessment in calves. First, it deals with the definition of pain and the challenges associated with the recognition of pain in calves. Then it proceeds to outline the different options and methods for subjective and objective pain assessment in calves, as described in the literature. Research data show that there are several tools suitable for the assessment of pain in calves, at least for research purposes. Finally, it concludes that for research purposes, various variables for the assessment of pain in calves are used in combination. However, there is no variable which can be used solely for the exclusive assessment of pain in calves. Also, further research is needed to describe biomarkers or variables which are easily accessible in the field practice.

Patterns of the low-dose dexamethasone suppression test in canine hyperadrenocorticism revisited

BACKGROUND

The low-dose dexamethasone suppression test (LDDT) is considered an accurate screening and valuable differentiation test in dogs with suspected hyperadrenocorticism (HAC). A recent study showed that the different response patterns not only provide complementary information about etiology, but also the probability of HAC in these patients.

OBJECTIVES

We aimed to determine the diagnostic test performance of LDDT response patterns in a population of dogs from an animal hospital.

METHODS

The electronic database was retrospectively searched for dogs suspected of HAC that were given an LDDT. Dogs with acute non-adrenal illnesses during the test were excluded. Response patterns were classified as complete suppression, lack of suppression, partial suppression, escape, inverse, and increasing patterns. Cortisol concentrations ≥ 27.59 nmol/L (≥1 µg/dL) 8 hours after dexamethasone administration were considered positive results irrespective of the patterns observed. Calculations included likelihood ratios (LRs) and predictive values (PVs).

RESULTS

HAC and non-adrenal illness were diagnosed in 115 (54%) and 62 (46%) dogs, respectively. The positive (+) LRs (95% CI) for the lack of suppression, partial suppression, escape, and an inverse pattern to diagnose HAC were infinite, 8.09 (2-32.72), 3.23 (0.75-14), and 0.2 (0.06-0.73), respectively.

CONCLUSIONS

The study confirms that the "lack of suppression" pattern strongly supports a diagnosis of HAC. It shows that the "partial suppression" pattern moderately increases, and the "inverse" pattern decreases the likelihood of HAC. The fact that the study found no association between the "escape" pattern and a diagnosis of HAC, does not support its integration into decision making.

Evaluation of serum cortisol concentration as a prognostic indicator for nonsurvival to hospital discharge in critically ill dogs

OBJECTIVE

To investigate whether serum cortisol (SC) concentration is a useful prognostic indicator for survival versus nonsurvival to hospital discharge in critically ill dogs.

ANIMALS

229 client-owned dogs.

PROCEDURES

Medical records were retrospectively reviewed to identify critically ill dogs that were hospitalized between January 2010 and May 2018 and that had SC concentrations measured ≤ 3 days after admission. Results for SC concentrations were compared for dogs grouped by survival versus nonsurvival to hospital discharge, with versus without sepsis, and other variables of interest. The predictive value of SC concentration for nonsurvival to hospital discharge was assessed (OR, sensitivity, and specificity) for cutoffs determined from a ROC curve or reference limit.

RESULTS

Median SC concentration was higher in dogs that did not survive to hospital discharge (8.5 μg/dL; interquartile [25th to 75th percentile] range, 4.8 to 11.8 μg/dL), compared with concentration in those that were discharged alive (4.5 μg/dL; interquartile range, 2.5 to 6.9 μg/dL). The area under the ROC curve was 0.72 (95% confidence interval [CI], 0.64 to 0.81) for SC concentration predicting nonsurvival. The calculated optimum cutoff of SC concentration was 7.6 μg/dL, at which the OR, sensitivity, and specificity for nonsurvival were 5.4 (95% CI, 2.7 to 10.9), 58%, and 80%, respectively. Alternatively, when the upper reference limit for SC concentration (5.8 μg/dL) was used as the cutoff, the OR, sensitivity, and specificity for nonsurvival were 3.6 (95% CI, 1.8 to 7.1), 67%, and 64%, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that SC concentration could be used as part of an overall assessment of prognosis in critically ill dogs.

Prevalence and characterization of hypoadrenocorticism in dogs with signs of chronic gastrointestinal disease: A multicenter study

Background

Dogs with hypoadrenocorticism (HA) frequently show signs of gastrointestinal disease (SGD). The prevalence of dogs presented for chronic SGD with HA is unknown.

Objectives

The aims of this study were to determine the prevalence of HA in dogs with chronic SGD and to identify clinical and laboratory variables for HA in this population.

Animals

One hundred fifty‐one dogs with chronic SGD.

Methods

In this multicentered prevalence study a standardized workup was performed in prospectively enrolled dogs with SGD > 3 weeks duration. Basal serum cortisol concentration was measured in every dog with ACTH stimulation test (ACTHST) if basal serum cortisol concentration was <3 μg/dL.

Results

Basal serum cortisol concentration was <3 μg/dL in 80/151 (53%) dogs, <2 μg/dL in 42/151 (28%) dogs, and < 1 μg/dL in 9/151 (6%) dogs. In 6/151 dogs HA was diagnosed based on ACTHST (stimulated serum cortisol concentration < 2 μg/dL), a prevalence of 4%. There was no difference in history, physical examination, and laboratory variables between dogs with HA and those with other causes of chronic SGD. In 4/6 dogs with HA, there was melena or hematochezia indicating gastrointestinal blood loss. Hyperkalemia, hyponatremia, or both was not observed in any dog.

Conclusion and Clinical Importance

The prevalence of HA among dogs with chronic SGD is higher than in the general population. Based on these results, testing adrenal function should be performed as a standard screening test in dogs with chronic SGD to differentiate between HA and chronic enteropathies.

Analytic performance evaluation of a veterinary-specific ELISA for measurement of serum cortisol concentrations of dogs

OBJECTIVE To investigate the precision of an ELISA for measurement of serum cortisol concentration (SCC) in dogs, assess agreement between this ELISA and 2 validated chemiluminescence assays (CLAs), and evaluate the clinical implications of any bias associated with this ELISA when measuring SCC in dogs. DESIGN Evaluation study. SAMPLE 75 stored, frozen serum samples from client-owned dogs. PROCEDURES Enzyme-linked immunosorbent assay precision was evaluated by measuring SCC of pooled serum samples. Agreement with standard methods was evaluated with Spearman rank correlation, Passing-Bablok regression, and Bland-Altman analysis to compare SCCs obtained with the ELISA and the 2 CLAs. An error grid was used to evaluate identified bias. RESULTS Within-laboratory coefficients of variation for pooled serum samples with low, medium, and high SCCs were 21.4%, 28.9%, and 13.0%, respectively. There was a high correlation between ELISA results (for all samples combined) and results of the 2 CLAs (CLA 1, r = 0.96; CLA 2, r = 0.97), but constant and proportional biases between the ELISA and CLAs were present at all concentrations. Clinically important disagreement between ELISA results and CLA results occurred in 16 of 63 (25%) samples, particularly with low and high SCCs. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that the rate of clinical disagreement between the ELISA and CLAs was sufficiently high to recommend that equivocal results obtained with the ELISA be confirmed by a reference laboratory. Further evaluation of analytic performance of the ELISA should focus on samples with very high and very low SCCs.

Evaluation of individual low-dose dexamethasone suppression test patterns in naturally occurring hyperadrenocorticism in dogs

BACKGROUND

Dogs with hyperadrenocorticism (HAC) may be more mildly affected at the time of diagnosis today, which could influence the prevalence of associated clinical and clinicopathological abnormalities and diagnostic test performance. Different low-dose dexamethasone suppression test (LDDST) result patterns have not been evaluated individually.

OBJECTIVES

To assess the current features of HAC and evaluate if the diagnostic test performance of individual LDDST result patterns differ.

ANIMALS

One hundred and twenty-three dogs undergoing investigation for HAC.

METHODS

Retrospective evaluation of dogs in which a LDDST was performed and HAC confirmed or excluded by alternative means. Cases with basal cortisol concentrations (t0 ) < 1 μg/dL were excluded. Each LDDST result was classified as (a) complete suppression (t3 and t8  < 1 μg/dL), (b) lack of suppression (t3 and t8  > 1 μg/dL and both > 50% t0 ), (c) partial suppression (t3 and t8  > 1 μg/dL but either < 50% t0 ), (d) escape (t8  > 1 μg/dL and t3  < 1 μg/dL) or (e) inverse (t3  > 1 μg/dL and t8  < 1 μg/dL) pattern.

RESULTS

Fifty-nine (48%) dogs were diagnosed with HAC and 64 (52%) with non-adrenal illness. Hyperadrenocorticism cases had similar clinicopathological abnormalities compared to previous reports. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) (95% confidence interval [CI]) of the LDDST for diagnosing HAC were 96.6 (91.9-100)%, 67.2 (55.7-78.7)%, 73.1 (63.2-82.9)%, and 95.6 (89.5-100)%, respectively. Lack of suppression pattern had the highest PPV (93.9 [85.8-100]%) followed by the partial suppression pattern (67.9 [50.6-85.2]%) and escape or inverse pattern (36.8 [15.1-58.5]%).

CONCLUSIONS AND CLINICAL IMPORTANCE

A lack of suppression LDDST pattern has the highest PPV for diagnosing HAC followed by a partial suppression pattern. By contrast, the escape or inverse pattern provided limited support of HAC.

The precision of predicting the time of onset of parturition in the bitch using the level of progesterone in plasma during the preparturient period

Precise prediction of the time of onset of parturition in the bitch is of clinical importance. Many parturition management cases in clinical practice are presented in the last two weeks of pregnancy without a reliable estimate of the parturition date. The aim of this study was to assess the value of a single progesterone level in the blood plasma from a preparturient bitch to predict the time of onset of parturition. The temporal relationship between the decrease in the plasma progesterone levels and the time of cervical dilatation (TCD)-which correlates to the onset of stage 1 of parturition-was evaluated in 25 bitches in the preparturient period. Among bitches destined to reach TCD within 12 h there is a 2% probability of having a plasma progesterone level of 15.8 nmoL/L or above and a 6% probability of having a level of 8.7 nmoL/L or above. Conversely, if the level is below 8.7 nmoL/L there is a 99% probability of reaching TCD within 48 h and if the level is below 3.18 nmoL/L there is a 100% probability of reaching TCD within 24 h. These results allow the veterinary obstetrician to make prompt decisions in the management of parturition.

Pre-trilostane and three-hour post-trilostane cortisol to monitor trilostane therapy in dogs

It is recommended that trilostane therapy of canine hyperadrenocorticism is monitored using an ACTH stimulation test, however this has never been validated. Three cortisol concentrations (pre-trilostane, 3-hour posttrilostane and 1-hour post-ACTH stimulation) were compared to a clinical score obtained from an owner questionnaire. There were 110 sets of 3 cortisol measurements and questionnaires obtained from 67 trilostane treated dogs. Questionnaire results were used to classify each dog as well or unwell. Well dogs were then categorised as having excellent, moderate or poor hyperadrenocorticism control, using thresholds produced by 14 independent veterinarians. Correlation co-efficients were used to compare the three cortisol concentrations to the owner score and the Kruskal Wallis and Mann-Whitney U tests were used to compare the three cortisol concentrations between categories of control. Cortisol cut-off values between significantly different categories were determined using ROC curves. Pre-trilostane and 3-hour post-trilostane cortisol were better correlated to the owner score and had cut-offs to differentiate between categories of control that had superior sensitivity and specificity results, than the post-ACTH cortisol. Iatrogenic hypoadrenocorticism was not detected in any unwell dog. This study shows that the pre-trilostane and 3-hour post-trilostane cortisol are potentially better monitoring methods than the ACTH stimulation test.

Comparison of Survival Times for Dogs with Pituitary-Dependent Hyperadrenocorticism in a Primary-Care Hospital: Treated with Trilostane versus Untreated

Background

Although pituitary‐dependent hyperadrenocorticism (PDH) is one of the most common endocrinopathies in dogs, the effects of withholding treatment on survival time in dogs with PDH remain unclear.

Hypothesis/Objectives

The purpose of this study was to clarify the effects of treatment in dogs with PDH by comparing survival times between dogs treated with trilostane and untreated dogs.

Animals

Forty‐three dogs diagnosed with PDH at a primary‐care hospital in Japan between June 2009 and January 2014.

Methods

Retrospective cohort study. The medical records of dogs with PDH treated with trilostane (n = 17) or left untreated (n = 26) were reviewed retrospectively. Survival analysis at 2 years after diagnosis of PDH was performed.

Results

Median survival time for the trilostane group was not reached (95% confidence interval [CI], 443 days–not applicable) and was significantly longer than the 506 days (95% CI, 292–564 days; P = .016) for the untreated group. Multivariate Cox proportional hazards analysis (including age at diagnosis, basal cortisol concentration at diagnosis, and treatment group) only identified assignment to the untreated group (hazard ratio, 5.01; 95% CI, 1.63–15.44) as associated with increased mortality.

Conclusions and Clinical Importance

The results of this retrospective cohort study suggest that withholding treatment for dogs with PDH might be associated with a higher risk of death. This represents the largest study to date to report survival times of untreated dogs with PDH.

Evaluation of Basal Serum or Plasma Cortisol Concentrations for the Diagnosis of Hypoadrenocorticism in Dogs

Background

Previous studies that included limited numbers of affected dogs have suggested basal cortisol concentrations ≤55 nmol/L (2 μg/dL) are sensitive, but nonspecific, for a diagnosis of hypoadrenocorticism. A detailed assessment of the diagnostic utility of basal cortisol concentrations is warranted.

Hypothesis/Objectives

To evaluate the utility of basal cortisol concentrations for the diagnosis of hypoadrenocorticism in a large number of dogs, including those with and without serum electrolyte abnormalities.

Animals

Five hundred and twenty‐two dogs, including 163 dogs with hypoadrenocorticism, 351 dogs with nonadrenal gland illness, and 8 dogs with equivocal results.

Methods

Retrospective study. Basal and post‐ACTH cortisol concentrations and sodium and potassium concentrations were collected from medical records. A receiver operating characteristic (ROC) curve was constructed for basal cortisol concentrations by standard methodologies. Sensitivity, specificity, and predictive values were determined for various cut‐points.

Results

The area under the ROC curve was 0.988 and was similarly excellent regardless of serum electrolyte concentrations. At the most discriminatory cut‐point of 22 nmol/L (0.8 μg/dL), sensitivity and specificity were 96.9 and 95.7%, respectively. A basal cortisol concentration of ≤55 nmol/L (2 μg/dL) resulted in a sensitivity of 99.4%. Conversely, a basal cortisol concentration of ≤5.5 nmol/L (0.19 μg/dL) resulted in a specificity of 99.1%.

Conclusions and Clinical Importance

Similar to findings in previous studies, basal cortisol concentrations >55 nmol/L (2 μg/dL) are useful in excluding a diagnosis of hypoadrenocorticism. Interestingly, excellent specificities and positive predictive values were observed at lower cut‐point cortisol concentrations.

Serum cortisol concentrations in dogs with pituitary-dependent hyperadrenocorticism and atypical hyperadrenocorticism

Background

Atypical hyperadrenocorticism (AHAC) is considered when dogs have clinical signs of hypercortisolemia with normal hyperadrenocorticism screening tests.

Hypothesis/Objectives

To compare cortisol concentrations and adrenal gland size among dogs with pituitary‐dependent hyperadrenocorticism (PDH), atypical hyperadrenocorticism (AHAC), and healthy controls.

Animals

Ten healthy dogs, 7 dogs with PDH, and 8 dogs with AHAC.

Method

Dogs were prospectively enrolled between November 2011 and January 2013. Dogs were diagnosed with PDH or AHAC based on clinical signs and positive screening test results (PDH) or abnormal extended adrenal hormone panel results (AHAC). Transverse adrenal gland measurements were obtained by abdominal ultrasound. Hourly mean cortisol (9 samplings), sum of hourly cortisol measurements and adrenal gland sizes were compared among the 3 groups.

Results

Hourly (control, 1.4 ± 0.6 μg/dL; AHAC, 2.9 ± 1.3; PDH, 4.3 ± 1.5) (mean, SD) and sum (control, 11.3 ± 3.3; AHAC, 23.2 ± 7.7; PDH, 34.7 ± 9.9) cortisol concentrations differed significantly between the controls and AHAC (P < .01) and PDH (P < .01) groups. Hourly (P < .01) but not sum (P = .27) cortisol concentrations differed between AHAC and PDH dogs. Average transverse adrenal gland diameter of control dogs (5.3 ± 1.2 mm) was significantly less than dogs with PDH (6.4 ± 1.4; P = .02) and AHAC (7.2 ± 1.5; P < .01); adrenal gland diameter did not differ (P = .18) between dogs with AHAC and PDH.

Conclusions and Clinical Importance

Serum cortisol concentrations in dogs with AHAC were increased compared to controls but less than dogs with PDH, while adrenal gland diameter was similar between dogs with AHAC and PDH. These findings suggest cortisol excess could contribute to the pathophysiology of AHAC.

Basal serum cortisol concentration as a screening test for hypoadrenocorticism in dogs

Background

Measurement of basal serum or plasma cortisol concentration is used as a screening test for hypoadrenocorticism in dogs, but is not well characterized.

Objectives

To evaluate the sensitivity and specificity of basal serum cortisol to detect hypoadrenocorticism in a population of dogs with a clinical suspicion of hypoadrenocorticism.

Animals

Four hundred and fifty dogs with nonadrenal gland illness and 14 dogs with naturally occurring hypoadrenocorticism were included.

Methods

Retrospective case‐control study. The records of all dogs having had an ACTH stimulation test performed between January 2005 and September 2011 at the University of Bristol were reviewed. Dogs were included if the test was performed as a screening for hypoadrenocorticism. The sensitivity and specificity of basal serum cortisol concentration to detect dogs with hypoadrenocorticism were calculated using 2 cut‐offs and compared to the gold standard ACTH stimulation test.

Results

Using a cut‐off of ≤2 μg/dL (≤55 nmol/L), the sensitivity and specificity of basal cortisol to detect hypoadrenocorticism were 100% and 63.3%, respectively, whereas for a cut‐off of ≤1 μg/dL (≤28 nmol/L), the sensitivity and specificity were 85.7% and 91.8%, respectively.

Conclusions and Clinical Importance

Measurement of basal serum cortisol is useful as a screening test for hypoadrenocorticism in dogs using a cut‐off of ≤2 μg/dL (≤55 nmol/L), and the disease is unlikely with a basal serum cortisol >2 μg/dL (>55 nmol/L). A basal serum cortisol ≤2 μg/dL (≤55 nmol/L) cannot be used to diagnose hypoadrenocorticism, and an ACTH stimulation test should be performed in these cases.

Measurement of thyroxine and cortisol in canine and feline blood samples using two immunoassay analysers

OBJECTIVES

The AIA-360 (Tosoh Corporation) is an automated immunoassay analyser. The aims of this study were to estimate the precision of thyroxine and cortisol AIA-360 immunoassays in canine and feline samples and to compare the results produced with those obtained by a chemiluminescence analyser (Immulite® 1000, Siemens).

METHODS

Blood samples from 240 clinical cases (60 dogs and 60 cats for both thyroxine and cortisol) were analysed using both instruments.

RESULTS

Deming regression calculations showed excellent correlation (thyroxine, canine rs  = 0 · 94, feline rs  = 0 · 97; cortisol, canine rs  = 0 · 97, feline rs  = 0 · 97). Agreement between the two instruments was examined by Bland-Altman difference plots, which identified wide confidence intervals and outliers for thyroxine (canine n = 6, feline n = 4) and cortisol (canine n = 3, feline n = 4) results. Inter/intra-run precision of the AIA-360 was excellent for both cortisol and thyroxine (coefficients of variation <7%).

CLINICAL SIGNIFICANCE

The instrument showed excellent correlation for cortisol and thyroxine in canine and feline samples demonstrating that the AIA-360 can be used in clinical practice. The agreement studies suggest that the results from the AIA-360 cannot be used interchangeably with those generated by the Immulite 1000 and should be interpreted using reference intervals that have been established specific to the AIA-360.

Comparison of VIDAS and radioimmunoassay methods for measurement of cortisol concentration in bovine serum

Radioimmunoassay (RIA) is the “gold standard” method for evaluation of serum cortisol concentration. The VIDAS cortisol test is an enzyme-linked fluorescent assay designed for the MiniVidas system. The aim of this study was to compare the VIDAS method with RIA for measurement of bovine serum cortisol concentration. Cortisol concentrations were evaluated in 40 cows using both VIDAS and RIA methods, the latter as the reference method. A paired Student's t-test, Pearson's correlation analysis, Bland-Altman plot, and Deming regression analysis were used to compare the two methods. There was no statistically significant difference between mean serum cortisol concentrations measured by VIDAS or RIA methods (P = 0.6570). Both methods were able to detect significant differences in mean low and high cortisol concentrations (P < 0.00014 RIA and P < 0.0016 VIDAS). The correlation coefficient was low, but a Bland-Altman plot and Deming regression analysis show neither constant nor proportional error. The VIDAS method produced slightly higher values than RIA, but the difference was small and in no case did the mean value move the normal range. Results suggest that VIDAS method is suitable for the determination of bovine serum cortisol concentration in studies of large numbers of animals.

Validation of an automated chemiluminescent immunoassay for salivary cortisol measurements in pigs

The aim of the current study was to validate an automated immunoassay for cortisol quantification in the saliva of pigs. The assay had intra- and interassay coefficients of variation lower than 16%, in all cases. The limit of detection was 0.016 µg/dl, and the lower quantification limit was 0.197 µg/dl. The assay also demonstrated a high level of accuracy, as determined by linearity under dilution and recovery tests. In addition, this assay was used to quantify cortisol in 2 models of stress: 1 in which animals were immobilized with a nose-snare and 1 in which pigs were transported for a duration of 30 min. In both cases, a significant increase (P < 0.01) in salivary cortisol was detected after the stressful situation. Overall, the assay validated in the present study could be used for the evaluation of cortisol changes in stressful situations.

Electroacupuncture versus morphine for the postoperative control pain in dogs

PURPOSE

[corrected] To compare the postoperative analgesic effects of electroacupuncture, morphine or sham acupuncture in dogs undergoing mastectomy.

METHODS

Thirty client-owed dogs undergoing to mastectomy were randomly assigned to three groups of 10 animals each and received either morphine (T-M), the electroacupuncture (T-EA) or sham procedure (T-Sham). Pre-anesthetic medication was acepromazine (0.05 mg kg(-1), IM). Anesthesia was induced with propofol (4 to 5 mg kg(-1), IV) and maintained with isoflurane. Postoperatively pain degree was assessed using a numerical rating scale. Dogs were scored at 1, 3, 6 and 12 hours post-extubation. If the pain score was ≥6, supplemental morphine was administered. Serum cortisol concentration was measured before pre-anesthetic medication, at 45 minutes after the anesthetic induction, and at 1, 3 and 6 hours post-extubation.

RESULTS

The pain score did not differ among the treatments, but rescue analgesia was lower in the T-EA group (2 of 10 dogs), when compared with T-Sham (6 of 10 dogs) and T-M (6 of 10 dogs) groups. Serum cortisol concentration did not differ among the treatments.

CONCLUSION

Electroacupuncture reduces the postoperative analgesic requirement and promotes satisfactory analgesia in dogs undergoing mastectomy.

Comparison of the VIDAS and IMMULITE-2000 methods for cortisol measurement in canine serum

BACKGROUND

Serum cortisol concentration is often measured in dogs for the diagnosis and monitoring of adrenal disease. An enzyme-linked fluorescent assay (VIDAS method) on the MiniVidas analyzer has been validated for the measurement of cortisol concentration in human serum and could have applications for canine samples.

OBJECTIVE

The aim of this study was to compare canine cortisol results obtained using the VIDAS method with those obtained using the IMMULITE-2000 immunoassay, which has previously been validated for canine serum.

METHODS

The concentration of cortisol in 40 canine serum samples was determined concurrently with the VIDAS and IMMULITE methods, the latter as the reference method. Pearson's correlation coefficient, linear, and Deming regression analyses and Bland-Altman analysis were used to compare the 2 methods. Acceptability of the new method was judged using a medical decision chart (MEDx chart).

RESULTS

Cortisol concentrations obtained with the IMMULITE method ranged from 23.1 to 1380 nmol/L. Correlation (r=.977) and simple linear regression (slope=1.0722, confidence interval [CI] 0.996-1.148; intercept=-4.799, CI -42.838 to 33.240) revealed no proportional or constant error. Based on Deming regression and a Bland-Altman plot the 2 methods gave comparable results. The MEDx chart indicated that performance of the new method was good at decision limits of 40, 132, and 480 nmol/L.

CONCLUSION

Results of the VIDAS method were comparable to those of the IMMULITE-2000 reference method such that the VIDAS may be used as an alternative assay to evaluate serum cortisol concentration in dogs for the diagnosis of adrenal disease.

Phenolics: occurrence and immunochemical detection in environment and food

Phenolic compounds may be of natural or anthropogenic origin and be present in the environment as well as in food. They comprise a large and diverse group of compounds that may be either beneficial or harmful for consumers. In this review first a non-exhausting overview of interesting phenolics is given, in particular with regards to their presence in environment and food. For some of these compounds, beneficial, toxicological and/or optionally endocrine disrupting activities will be presented. Further, immunochemical detection and/or isolation methods developed will be discussed, including advantages and disadvantages thereof in comparison with conventional analytical methods such as HPLC, GC, MS. A short overview of new sensor-like methods will also be included for present and future application.