Evaluation of a point-of-care benchtop analyzer for quantitative measurement of C-reactive protein in canine serum and plasma.

BACKGROUND: Canine C-reactive protein (cCRP) is an acute-phase protein that increases dramatically with inflammation and has potential utility in monitoring disease progression and response to treatment. Rapid, automated point-of-care test (POCT) formats could enhance the clinical utility of cCRP measurement. OBJECTIVES: We aimed to evaluate the VetChroma canine-specific POCT assay for the quantitative measurement of cCRP in canine serum or plasma. METHODS: Serum and plasma from discarded canine diagnostic samples were used. Evaluation included intra- and inter-assay coefficients of variation and observed total error (TEobs ), linearity and spike recovery, the effect of interfering substances and sample matrices, and a method comparison study. RESULTS: Intra-assay variation ranged from 2.5%-6.1%, and inter-assay variation ranged from 2.1%-5.4%. The TEobs ranged from 15.1%-19.7%. The assay was linear over the manufacturer's analytical range with no evidence of constant or proportional bias. Recovery of purified cCRP from canine serum ranged from 116.2% to 138.4%. Hemolysis, icterus, and turbidity did not interfere with the assay. The comparison of paired plasma and serum samples revealed constant and proportional bias. Comparison of the VetChroma cCRP assay to a commercial cCRP ELISA revealed significantly different results. CONCLUSIONS: The VetChroma cCRP assay has acceptable test performance to measure serum cCRP concentration. The POCT protocol and test kit are valid for clinical use, although results obtained using other cCRP assays or plasma may not be directly compared.

Plasma and tissue angiotensin-converting enzyme 2 activity and plasma equilibrium concentrations of angiotensin peptides in dogs with heart disease.

BACKGROUND: Angiotensin-converting enzyme 2 (ACE2) is a homologue of angiotensin-converting enzyme (ACE) and produces angiotensin peptides (APs), such as angiotensin 1-9 and 1-7 that are vasodilatory and natriuretic, and act to counterbalance angiotensin II. HYPOTHESIS: Evidence of ACE2 can be found in tissues and plasma of dogs. Equilibrium concentrations of renin angiotensin aldosterone system (RAAS) APs differ in dogs with heart disease compared to healthy dogs and recombinant human ACE2 (rhACE2) alters relative concentrations of APs. ANIMALS: Forty-nine dogs with and 34 dogs without heart disease. METHODS: Immunohistochemistry and assays for tissue and plasma ACE2 activity and equilibrium concentrations of plasma RAAS APs were performed. RESULTS: Immunolabeling for ACE2 was present in kidney and myocardial tissue. Median plasma ACE2 activity was significantly increased in dogs with congestive heart failure (CHF; 6.9 mU/mg; interquartile range [IQR], 5.1-12.1) as compared to control (2.2 mU/mg; IQR, 1.8-3.0; P = .0003). Plasma equilibrium analysis of RAAS APs identified significant increases in the median concentrations of beneficial APs, such as angiotensin 1-7, in dogs with CHF (486.7 pg/mL; IQR, 214.2-1168) as compared to those with preclinical disease (41.0 pg/mL; IQR, 27.4-45.1; P < .0001) or control (11.4 pg/mL; IQR, 7.1-25.3; P = .01). Incubation of plasma samples from dogs with CHF with rhACE2 increased beneficial APs, such as angiotensin 1-9 (preincubation, 10.3 pg/mL; IQR, 4.4-37.2; postincubation, 2431 pg/mL; IQR, 1355-3037; P = .02), while simultaneously decreasing maladaptive APs, such as angiotensin II (preincubation, 53.4 pg/mL; IQR, 28.6-226.4; postincubation, 2.4 pg/mL; IQR, 0.50-5.8; P = .02). CONCLUSIONS AND CLINICAL IMPORTANCE: Recognition of the ACE2 system expands the conventional view of the RAAS in the dog and represents an important potential therapeutic target.

Prospective screening for occult cardiomyopathy in dogs by measurement of plasma atrial natriuretic peptide, B-type natriuretic peptide, and cardiac troponin-I concentrations.

OBJECTIVE: To evaluate the use of measuring plasma concentrations of atrial natriuretic peptide (ANP), B-type natriuretic peptide (BNP), and cardiac troponin-I (cTnI) to detect dogs with occult dilated cardiomyopathy (DCM). ANIMALS: 118 client-owned dogs. PROCEDURES: Dogs were prospectively examined by use of ECG; echocardiography; and evaluation of concentrations of ANP, BNP, and cTnI. Occult DCM was diagnosed by evaluation of echocardiographic left ventricular dimensions and detection of ventricular arrhythmias on ECG. Sensitivity and specificity of assays for measurement of plasma concentrations of ANP, BNP, and cTnI to detect dogs with occult DCM were determined. RESULTS: Occult DCM was diagnosed in 21 dogs. A concentration of > 6.21 pg/mL for BNP had a sensitivity of 95.2% and specificity of 61.9% for identifying dogs with occult DCM. In contrast, concentrations of ANP and cTnI had relatively low predictive values. CONCLUSIONS AND CLINICAL RELEVANCE: Blood-based screening for occult DCM in dogs can be accomplished by use of a BNP assay. Additional studies should be performed to optimize this method of screening dogs to detect occult DCM.

A novel aortic coarctation model for studying hypertension in the pig.

We have developed a reproducible renovascular model of hypertension via a controllable, suprarenal aortic coarctation in the pig. This model has many potential applications, including investigation of the effects of acute hypertension in the conscious animal; identification of cardiac and vascular adaptations to chronic hypertension and their reversal; determining the effect of pharmacologic agents or other interventions on hypertension; and furthering our understanding of the implications of chronic hypertension on neurologic function. A totally implantable system was devised by attaching a reinforced silicone vascular occluder to a vascular access port. The occluder was placed around the suprarenal aorta proximal to the diaphragm. Ten pigs were made hypertensive by sequentially inflating the occluder. In six pigs, telemetric monitoring of blood pressure was used to determine when the pigs had reached target pressures (mean arterial blood pressure >150 mm Hg). Four pigs did not have telemetry units placed and blood pressure and heart rate were monitored for 4 weeks by periodically restraining the pigs in a sling. Two pigs reversed their occlusion due to presumed technical errors; the remaining pigs were studied for 4 (n = 5) or 8 (n = 3) weeks and then euthanized. Advantages of this model of aortic coarctation are that the occlusions are performed in awake animals and excessive occlusion of the aorta resulting in neurologic dysfunction or other distress to the animal can be easily corrected by simply withdrawing a small amount of the fluid used for inflation of the occluder. Additionally, removal of the constriction does not require a second surgical procedure.