High-Dose Hydrocortisone Treatment Does Not Affect Serum C-Reactive Protein (CRP) Concentrations in Healthy Dogs.

Measuring C-reactive protein (CRP) in serum is a useful surrogate marker for assessing disease progression and treatment response in dogs with autoinflammatory diseases. Affected dogs often receive high-dose glucocorticoid treatment, but the effect of such treatment alone on serum CRP concentrations is unknown. We evaluated serum CRP concentrations via immunoassay (sandwich enzyme-linked immunosorbent assay and particle-enhanced turbidimetric immunoassay) in 12 healthy beagle dogs administered high-dose hydrocortisone (8 mg/kg q12 h) per os vs. placebo over 28 days (days 0, 1, 5, and 28) in a randomized parallel study design. Serum CRP concentrations slightly decreased during treatment or placebo but without a significant association with hydrocortisone administration (p = 0.761). Compared to baseline, serum CRP concentrations were decreased by >2.7-fold (minimum critical difference) in three hydrocortisone-treated dogs and two dogs in the placebo group on day 28, whereas an increase to >2.7-fold was seen in one dog receiving placebo. These results suggest a lack of confounding effects of high-dose hydrocortisone administration on serum CRP concentrations in healthy dogs. This might also hold in dogs with autoinflammatory conditions and/or administration of other high-dose corticosteroids, suggesting that CRP presents a suitable biomarker to monitor inflammatory disease processes. However, this needs confirmation by further studies evaluating corticosteroid-induced cellular (e.g., hepatic) transcriptome and proteome changes.

Analytical validation of commercial immunoassays for the measurement of cardiovascular peptides in the dog.

Immunoassays for the measurement of concentrations of the cardiovascular peptides pro-atrial natriuretic peptide (proANP), brain natriuretic peptide (BNPPen and BNPPhoe), endothelin-1 (ET-1Bio, ET-1IBL and ET-1Phoe) and big endothelin-1 (Big-ETBio and Big-ETIBL) were validated in canine serum by determination of intra-assay variability and dilutional parallelism. Commercial kits that showed good results were further validated by determination of intra- and inter-assay variability, dilutional parallelism and spiking recovery. Assays for proANP, BNPPhoe, ET-1IBL and Big-ETIBL showed acceptable results in the preliminary validation and were fully validated. The intra- and inter-assay variability was acceptable for all four assays, linearity was demonstrated and recovery rates were acceptable. The performances of the different immunoassays varied considerably, underscoring the importance of validation. Of the assays studied, proANP, BNP(Phoe), ET-1IBL and Big-ETIBL produced precise, reproducible and accurate results and can be recommended for clinical application.

Validation of an enzyme-linked immunosorbent assay (ELISA) for the measurement of canine S100A12.

BACKGROUND: Canine S100 calcium-binding protein A12 (cS100A12) shows promise as biomarker of inflammation in dogs. A previously developed cS100A12-radioimmunoassay (RIA) requires radioactive tracers and is not sensitive enough for fecal cS100A12 concentrations in 79% of tested healthy dogs. An ELISA assay may be more sensitive than RIA and does not require radioactive tracers. OBJECTIVE: The purpose of the study was to establish a sandwich ELISA for serum and fecal cS100A12, and to establish reference intervals (RI) for normal healthy canine serum and feces. METHODS: Polyclonal rabbit anti-cS100A12 antibodies were generated and tested by Western blotting and immunohistochemistry. A sandwich ELISA was developed and validated, including accuracy and precision, and agreement with cS100A12-RIA. The RI, stability, and biologic variation in fecal cS100A12, and the effect of corticosteroids on serum cS100A12 were evaluated. RESULTS: Lower detection limits were 5 µg/L (serum) and 1 ng/g (fecal), respectively. Intra- and inter-assay coefficients of variation were ≤ 4.4% and ≤ 10.9%, respectively. Observed-to-expected ratios for linearity and spiking recovery were 98.2 ± 9.8% (mean ± SD) and 93.0 ± 6.1%, respectively. There was a significant bias between the ELISA and the RIA. The RI was 49-320 µg/L for serum and 2-484 ng/g for fecal cS100A12. Fecal cS100A12 was stable for 7 days at 23, 4, -20, and -80°C; biologic variation was negligible but variation within one fecal sample was significant. Corticosteroid treatment had no clinically significant effect on serum cS100A12 concentrations. CONCLUSIONS: The cS100A12-ELISA is a precise and accurate assay for serum and fecal cS100A12 in dogs.

Serum and fecal canine α1-proteinase inhibitor concentrations reflect the severity of intestinal crypt abscesses and/or lacteal dilation in dogs.

Gastrointestinal (GI) protein loss, due to lymphangiectasia or chronic inflammation, can be challenging to diagnose. This study evaluated the diagnostic accuracy of serum and fecal canine α1-proteinase inhibitor (cα1PI) concentrations to detect crypt abscesses and/or lacteal dilation in dogs. Serum and fecal cα1PI concentrations were measured in 120 dogs undergoing GI tissue biopsies, and were compared between dogs with and without crypt abscesses/lacteal dilation. Sensitivity and specificity were calculated for dichotomous outcomes. Serial serum cα1PI concentrations were also evaluated in 12 healthy corticosteroid-treated dogs. Serum cα1PI and albumin concentrations were significantly lower in dogs with crypt abscesses and/or lacteal dilation than in those without (both P <0.001), and more severe lesions were associated with lower serum cα1PI concentrations, higher 3 days-mean fecal cα1PI concentrations, and lower serum/fecal cα1PI ratios. Serum and fecal cα1PI, and their ratios, distinguished dogs with moderate or severe GI crypt abscesses/lacteal dilation from dogs with only mild or none such lesions with moderate sensitivity (56-92%) and specificity (67-81%). Serum cα1PI concentrations increased during corticosteroid administration. We conclude that serum and fecal α1PI concentrations reflect the severity of intestinal crypt abscesses/lacteal dilation in dogs. Due to its specificity for the GI tract, measurement of fecal cα1PI appears to be superior to serum cα1PI for diagnosing GI protein loss in dogs. In addition, the serum/fecal cα1PI ratio has an improved accuracy in hypoalbuminemic dogs, but serum cα1PI concentrations should be carefully interpreted in corticosteroid-treated dogs.

Evaluation of four methods used to measure plasma insulin-like growth factor 1 concentrations in healthy cats and cats with diabetes mellitus or other diseases.

OBJECTIVE: To evaluate 4 methods used to measure plasma insulin-like growth factor (IGF) 1 concentrations in healthy cats and cats with diabetes mellitus or other diseases. ANIMALS: 39 healthy cats, 7 cats with diabetes mellitus, and 33 cats with other diseases. PROCEDURES: 4 assays preceded by different sample preparation methods were evaluated, including acid chromatography followed by radioimmunoassay (AC-RIA), acid-ethanol extraction followed by immunoradiometry assay (AEE-IRMA), acidification followed by immunochemiluminescence assay (A-ICMA), and IGF-2 excess followed by RIA (IE-RIA). Validation of the methods included determination of precision, accuracy, and recovery. The concentration of IGF-1 was measured with all methods, and results were compared among cat groups. RESULTS: The intra-assay coefficient of variation was < 10% for AC-RIA, A-ICMA, and AEE-IRMA and 14% to 22% for IE-RIA. The linearity of dilution was close to 1 for each method. Recovery rates ranged from 69% to 119%. Five healthy cats had IGF-1 concentrations > 1,000 ng/mL with the AEE-IRMA, but < 1,000 ng/mL with the other methods. Compared with healthy cats, hyperthyroid cats had significantly higher concentrations of IGF-1 with the A-ICMA method, but lower concentrations with the IE-RIA method. Cats with lymphoma had lower IGF-1 concentrations than did healthy cats regardless of the method used. CONCLUSIONS AND CLINICAL RELEVANCE: Differences in the methodologies of assays for IGF-1 may explain, at least in part, the conflicting results previously reported in diabetic cats. Disorders such as hyperthyroidism and lymphoma affected IGF-1 concentrations, making interpretation of results more difficult if these conditions are present in cats with diabetes mellitus.

Effect of twice-daily oral administration of hydrocortisone on the bile acids composition of gallbladder bile in dogs.

OBJECTIVE: To investigate the effects of twice-daily oral administration of hydrocortisone on the bile acids composition of gallbladder bile in dogs. ANIMALS: 6 placebo-treated control dogs and 6 hydrocortisone-treated dogs. PROCEDURES: Dogs received hydrocortisone (median dose, 8.5 mg/kg) or a gelatin capsule (control group) orally every 12 hours for 84 days. Gallbladder bile samples were obtained via percutaneous ultrasound-guided cholecystocentesis from each dog before (day 0 [baseline]), during (days 28, 56, and 84), and after (days 28p, 56p, and 84p) treatment for differentiated quantification of unconjugated bile acids and taurine-conjugated and glycine-conjugated bile acids via high-performance liquid chromatography-tandem mass spectrometry. RESULTS: Treatment with hydrocortisone for 84 days resulted in significant and reversible increases in the concentrations of unconjugated bile acids (ie, cholic, chenodeoxycholic, and deoxycholic acids) and a significant and reversible decrease in the concentration of total taurine-conjugated bile acids, compared with baseline or control group values. Treatment with hydrocortisone had no effect on bile concentrations of glycine-conjugated bile acids. CONCLUSIONS AND CLINICAL RELEVANCE: In dogs, hydrocortisone administration caused reversible shifts toward higher concentrations of the more hydrophobic unconjugated bile acids (chenodeoxycholic acid and deoxycholic acid) and toward lower concentrations of the amphipathic taurine-conjugated bile acids in gallbladder bile. These data suggest that similar bile acids changes could cause major alterations in gallbladder structure or function over time in hypercortisolemic dogs.

Endocrine hypertension in small animals.

Hypertension is classified as idiopathic or secondary. In animals with idiopathic hypertension, persistently elevated blood pressure is not caused by an identifiable underlying or predisposing disease. Until recently, more than 95% of cases of hypertension in humans were diagnosed as idiopathic. New studies have shown, however, a much higher prevalence of secondary causes, such as primary hyperaldosteronism. In dogs and cats, secondary hypertension is the most prevalent form and is subclassified into renal and endocrine hypertension. This review focuses on the most common causes of endocrine hypertension in dogs and cats.