Cloning and sequencing of the canine and feline cardiac troponin I genes

Analytical validation, sample stability, and clinical evaluation of a new high-sensitivity cardiac troponin I immunoassay for use in dogs, with comparison to a previous ultrasensitive assay

Cardiac troponin I (cTnI) is considered the gold standard biomarker for myocardial injury and shows a high degree of homology between humans and dogs. The ADVIA Centaur XP High-Sensitivity Troponin I (AC-cTnI-HS) assay has been validated for use in humans but not dogs. The study objectives were to analytically validate the AC-cTnI-HS assay in dogs, to assess correlation between the AC-cTnI-HS and a previous ADVIA Centaur TnI-Ultra (AC-cTnI-U) assay, to assess cTnI sample storage stability, and to clinically evaluate the AC-cTnI-HS assay in healthy dogs and dogs with cardiac disease. Canine serum samples were used for analytical validation. Intra- and inter-assay variability, dilutional parallelism, and spiking recovery were assessed. Samples from 196 client-owned dogs were evaluated (healthy dogs (n = 39) or dogs with congenital heart disease (n = 54), myxomatous mitral valve disease (n = 68), dilated cardiomyopathy (n = 15), or myocarditis (n = 20)). Inter- and intra-assay coefficient of variation (%CV) was between 2.8-41.4% and 3.8-30.2%, respectively, with pools with concentrations >20 pg/mL all having %CVs <10%. The observed to expected ratios for dilutional parallelism and spiking recovery experiments ranged between 92.3 and 266.7.0% and 84.3 and 108%, respectively. A strong correlation between the AC-cTnI-HS and AC-cTnI-U assays was observed (Spearman's ρ = 0.927), though a proportional bias existed, with AC-cTnI-HS assay concentrations being proportionally lower than AC-cTnI-U assay concentrations. Serum samples stored at -80°C had stable cTnI measurements for up to 2.7 years and after a single freeze-thaw cycle. Healthy dogs and dogs with congenital heart disease had significantly lower cTnI concentrations than dogs in the other three groups. The AC-cTnI-HS assay precisely, reproducibly, and accurately measures cTnI concentrations in dog serum with cTnI concentrations >20 pg/mL.

Atipamezole Reverses Cardiovascular Changes Induced by High-Dose Medetomidine in Cats Undergoing Sedation for Semen Collection

This study aimed at describing the change in echocardiographic variables after high-dose medetomidine and the reversal with atipamezole in six cats undergoing sedation for semen collection. Further cardiac Troponin I (cTnI) concentration and the effect of repeated sedation were assessed. Echocardiography was performed before and 20 min after sedation with 0.1 mg/kg medetomidine intramuscularly (IM) for urethral catheterisation. Prior to epididymectomy, S-ketamine was administered intravenously. Twenty minutes after reversal with 0.5 mg/kg atipamezole IM, the third echocardiography was performed. Sedation with medetomidine and reversal with atipamezole was repeated on day 7, 14, 21 and 28. Heart rate (HR) and rhythm were monitored throughout all sedations. On day 0 and 28 cTnI concentrations were measured before and after the procedure. After normality testing, the values were compared over time. The administration of medetomidine led to a marked reduction in HR, cardiac output and ventricular systolic function and a significant increase in left ventricular dimensions. Rhythm abnormalities, such as ventricular premature complexes and idioventricular rhythm, could be observed. The administration of atipamezole completely reversed sedation and the changes in haemodynamic variables. No significant increase in cTnI concentrations could be detected, although two out of six cats showed values above the reference range.

Biochemistry, Doppler echocardiography, and electrocardiography evaluation in captive owl monkeys (Aotus sp)

BACKGROUND

The cardiovascular system of owl monkeys has been studied due to frequent postmortem findings of heart disease in asymptomatic animals. The silent aspect and the difficulty of early diagnosis intensify the importance of studying the cardiovascular system in this species.

METHODS

Echocardiogram evaluation was carried out on 60 animals, grouped into suspect or non-suspect of having heart diseases, and evaluated through electrocardiogram, hematology, and biochemical tests.

RESULTS

Doppler echocardiography indicated two animals with suspicion of left ventricular hypertrophy and eight with dilated cardiomyopathy. Suspect animals had higher cardiac measurements and reduced shortening fraction. Troponin I was detectable in two animals (0.128 ng/mL and 0.584 ng/mL), and serum albumin concentration was significantly higher in non-suspect animals (P < .05).

CONCLUSIONS

The importance of echocardiographic measurements of IVSd, IVSs, LVIDd, LVIDs, LVPWd, LVPWs, LA, EF, and FS in the cardiac evaluation of captive owl monkeys was evidenced.

Evaluation of atrial natriuretic peptide and cardiac troponin I concentrations for assessment of disease severity in dogs with naturally occurring mitral valve disease

OBJECTIVE

To evaluate and compare the clinical usefulness of plasma atrial natriuretic peptide (ANP) and cardiac troponin-I (cTnI) concentrations for assessment of disease severity in dogs with naturally occurring mitral valve disease (MVD).

ANIMALS

316 dogs with MVD and 40 healthy control dogs.

PROCEDURES

Each dog underwent a physical examination and echocardiographic and thoracic radiographic assessments. Blood samples were obtained and processed for measurement of plasma ANP and cTnI concentrations. Dogs with MVD were categorized into 3 groups (stages B1 [no clinical signs or evidence of cardiac enlargement], B2 [no clinical signs with evidence of cardiac enlargement], and C [history of congestive heart failure and pulmonary edema]) on the basis of American College of Veterinary Internal Medicine guidelines. Receiver operating characteristic curve analysis was used to evaluate the accuracy of plasma ANP and cTnI concentrations for assessment of MVD severity.

RESULTS

Plasma ANP and cTnI concentrations increased as disease severity increased. Median plasma ANP concentrations for all 3 MVD groups and median plasma cTnI concentrations for the stage B2 and C groups were significantly greater than the corresponding concentrations for the control group. Plasma ANP concentration, but not cTnI concentration, appeared to be useful for detection of dogs with subclinical (stages B1 and B2) MVD, whereas both concentrations appeared useful for detection of dogs with stage C MVD.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that plasma ANP and cTnI concentrations should not be used independently to diagnose MVD but can be used to assess MVD severity and supplement echocardiographic findings.

Analytical quality assessment and method comparison of two immunoassays for the measurement of serum cardiac Troponin I in dogs and cats

BACKGROUND

Cardiac troponin I (cTnI) is a sensitive and specific biomarker for myocardial injury. Validation of point-of-care (POC) analyzers for cTnI measurement is valuable to the critical care setting, in which rapid results can facilitate prompt diagnoses. An immunoassay for detecting cTnI is available for the POC AIA-360 analyzer (Tosoh Bioscience), but this has not been validated using canine and feline serum.

OBJECTIVES

The objectives were (a) to determine precision, accuracy, and linearity of cTnI measurement using the AIA-360 immunoassay in pooled canine and feline samples, and (b) to compare results for individual canine and feline samples with those obtained using a reference chemiluminescence method (Immulite 1000, Siemens).

METHODS

Intra- and inter-assay repeatability was determined using pooled canine and feline samples, and the coefficient of variation (CV) was calculated for each. Pooled samples were also serially diluted to assess linearity. A modified spike and recovery analysis was performed by mixing pooled samples with different concentrations. Bland-Altman and Deming regression analyses were used to determine bias for individual samples, and the total observed error (TE_obs ) was calculated.

RESULTS

Coefficient of variation values were well within the required maximum of 20%. Linearity was demonstrated over the range of samples tested, and the recovery study showed minimal proportional inaccuracies. Although the correlation between the analyzers was excellent, there was a large mean bias due to relative proportional bias. Total observed error consequently exceeded the total allowable error (TE_A ).

CONCLUSION

Although, in most respects, the analyzer demonstrated adequate performance, pronounced bias contributed to the large TE_obs , indicating a requirement for analyzer-specific reference intervals.

Diagnostic utility of cardiac troponin I in cats with hypertrophic cardiomyopathy

Background

Cardiac troponin I (cTnI) is useful for assessing hypertrophic cardiomyopathy (HCM) in cats.

Objective

To measure plasma cTnI concentrations in healthy cats and evaluate the clinical utility of cTnI in determining the severity of HCM.

Animals

Clinically healthy cats (n = 88) and cats with HCM (n = 93).

Methods

Multicenter prospective study. Cats with HCM, including hypertrophic obstructive cardiomyopathy at various stages, were diagnosed using echocardiography. Plasma cTnI concentrations were analyzed by a commercial laboratory. Receiver‐operating characteristic curve analysis was used to evaluate the accuracy of plasma cTnI concentrations to detect HCM.

Results

The median cTnI concentration was 0.027 ng/mL (interquartile range, 0.012‐0.048 ng/mL) in healthy cats. Concentrations were significantly higher in diseased cats than in healthy controls, and concentrations were significantly higher in cats with heart failure than in asymptomatic cats. A plasma cTnI concentration of 0.163 ng/mL had a sensitivity of 62.0% and specificity of 100% when used to distinguish normal cats from asymptomatic HCM cats without left atrial dilatation. A cutoff of 0.234 ng/mL had high sensitivity (95.0%) and specificity (77.8%) for assessing heart failure. The areas under the receiver‐operating characteristic curves were 0.85 and 0.93, respectively.

Conclusions and Clinical Importance

Increased cTnI concentrations reflect the severity of HCM. If other causes of cardiac injury are ruled out, plasma cTnI concentration may be useful for predicting the severity of HCM in cats.

Cloning and Sequencing of Equine Cardiac Troponin I and Confirmation of Its Usefulness as a Target Analyte for Commercial Troponin I Analyzers

The analysis of cardiac troponin I (cTnI) in the diagnosis of myocardial injury in domestic animals is gaining popularity. In this study, equine cTnI was sequenced and compared with previously characterized cTnI from other species. A 6-amino-acid N-terminal deletion unique to the horse was identified. This deletion was outside the epitope region of cTnI recognized by most commercial immunoassays and did not affect the ability of a commercial analyzer system to detect recombinant equine cTnI. No function could be ascribed to the deleted portion. These data support the use of commercial analyzers in measuring equine cTnI.

Cardiac Troponins in Dogs and Cats

Cardiac troponins are sensitive and specific markers of myocardial injury. The troponin concentration can be thought of as a quantitative measure of the degree of injury sustained by the heart, however, it provides no information on the cause of injury or the mechanism of troponin release. Conventionally, the cardiac troponins have been used for diagnosis of acute myocardial infarction in humans and have become the gold standard biomarkers for this indication. They have become increasingly recognized as an objective measure of cardiomyocyte status in both cardiac and noncardiac disease, supplying additional information to that provided by echocardiography and ECG. Injury to cardiomyocytes can occur through a variety of mechanisms with subsequent release of troponins. Independent of the underlying disease or the mechanism of troponin release, the presence of myocardial injury is associated with an increased risk of death. As increasingly sensitive assays are introduced, the frequent occurrence of myocardial injury is becoming apparent, and our understanding of its causes and importance is constantly evolving. Presently troponins are valuable for detecting a subgroup of patients with higher risk of death. Future research is needed to clarify whether troponins can serve as monitoring tools guiding treatment, whether administering more aggressive treatment to patients with evidence of myocardial injury is beneficial, and whether normalizing of troponin concentrations in patients presenting with evidence of myocardial injury is associated with reduced risk of death.

Serum dosage of CPK-MB in dogs with ST deviation by chemiluminescence

Abstract: Although frequently in humans, hypoxic and ischemic heart diseases are poorly documented in dogs, with only few reports of acute myocardial infarction (AMI) in this species. Some electrocardiographic findings might suggest myocardium hypoxia/ischemia, like ST segment elevation or depression, but there are no studies showing whether deviations in ST segment are associated to myocardial injury and serum increase of creatine phosphokinase (CPK-MB). In order to investigate possible myocardial cells injury in poor perfusion conditions, 38 dogs were studied, 20 with normal electrocardiogram and 18 with ST segment elevation or depression, recorded in lead II, at a paper speed of 50 mm/sec and N sensibility (1mV=1cm). Serum measurement of creatine phosphokinase isoenzyme MB (CPK-MB) in normal dogs (group 1) determined control values (in ng/mL), which were compared to those obtained from dogs with deviation (group 2), which allowed confirmation or not of myocardial injury. CPK-MB mean values obtained from dogs in groups 1 and 2 were 0.540ng/ml (SD±0.890)ng/mL and 0.440ng/mL (SD±1.106), respectively. At a significance level of 5%, the relation of CPK-MB with age, mass and total creatine phosphokinase (CPK-T) was not significant in groups 1 and 2. CPK-MB showed no difference, at 5% level, between groups 1 and 2. In conclusion, it is possible to use the human chemiluminescent immunometric assay kit in canine species and that hypoxia/ischemia revealed by ST segment deviation does not mean significant myocardium injury.

Evaluation of blood cardiac troponin I concentrations obtained with a cage-side analyzer to differentiate cats with cardiac and noncardiac causes of dyspnea

OBJECTIVE

To determine whether measurement of blood cardiac troponin I (cTnI) concentrations with a cage-side analyzer could be used to differentiate cardiac from noncardiac causes of dyspnea in cats.

DESIGN

Prospective, multicenter study.

ANIMALS

44 client-owned cats with dyspnea and 37 healthy staff-owned cats.

PROCEDURES

Affected cats were examined because of dyspnea; treatment was administered in accordance with the attending clinician's discretion. Cats were judged to have a cardiac or noncardiac cause of dyspnea on the basis of results of physical examination, thoracic radiography, and echocardiography. Blood cTnI concentrations were determined with a cage-side analyzer on samples collected within 12 hours after admission of affected cats. Concentrations for healthy cats were obtained for comparison.

RESULTS

5 enrolled cats were excluded from the study because of concurrent cardiac and respiratory disease. Of the remaining 39 cats with dyspnea, 25 had a cardiac cause and 14 had a noncardiac cause. The 25 cats with a cardiac cause of dyspnea had a significantly higher blood cTnI concentration than did the 37 healthy cats or the 14 cats with a noncardiac cause of dyspnea.

CONCLUSIONS AND CLINICAL RELEVANCE

Measurement of cTnI concentrations with a cage-side assay in emergency settings may be useful for differentiating cardiac from noncardiac causes of dyspnea in cats.

Evaluation of a high-sensitivity assay for measurement of canine and feline serum cardiac troponin I

BACKGROUND

Cardiac troponins are established as the gold standard biomarkers for acute cardiac injury. As even small elevations of cardiac troponins have prognostic relevance in people, it is important to investigate the performance of sensitive assays for use in veterinary medicine.

OBJECTIVES

The aim of this study was to evaluate analytical and overlap performance of a high-sensitivity cardiac troponin I (cTnI) assay, the ADVIA Centaur CP TnI-Ultra assay, in dogs and cats.

METHODS

Serum samples from dogs and cats with cardiac disease or arrhythmias, along with samples of purified canine free cTnI and complexed cTnI, T, and C (cTnI-T-C) were used in the assay validation study. Intra- and inter-assay variation, linearity under dilution, spike-and-recovery analysis, and detection limit were investigated to assess analytical performance. Overlap performance was evaluated based on the ability of the assay to discriminate between healthy animals and animals with cardiac disease or arrhythmias.

RESULTS

Intra-assay variation of cTnI in canine and feline serum ranged from 3.9 to 6.4% and from 4.0 to 4.8%, respectively. Inter-assay variation ranged from 2.7 to 4.7% and from 4.0 to 7.8%, respectively. The assay demonstrated acceptable linearity under dilution within a clinically relevant range of cTnI concentrations. Spike-and-recovery analysis showed excessive recovery in the range 150.7%-242.0% for free cTnI and 121.1-196.3% for complexed cTnI-T-C, partly due to a matrix effect. Overlap performance was acceptable as animals with cardiac disease or arrhythmias (n = 45 dogs, n = 53 cats) had significantly higher cTnI concentrations than healthy controls (P < .0001).

CONCLUSIONS

The results confirm the ADVIA Centaur CP TnI-Ultra assay as a valuable tool for assessing cTnI and thus myocardial injury in dogs and cats.

Cardiac troponin I concentrations in normal dogs and cats using a bedside analyzer

OBJECTIVE

To develop reference ranges for cardiac troponin I (cTnI) in normal dogs and cats using the Biosite Triage Meter((R)).

BACKGROUND

Reference ranges for cTnI in dogs and cats have not yet been reported for this inexpensive bedside analyzer.

METHODS

Purified free canine cTnI was diluted to 5 known concentrations to assess linearity and recovery. Interassay and intraassay precision were evaluated using 3 dilutions obtained from a dog with an elevated cTnI concentration. EDTA plasma was obtained from 55 normal dogs and 58 normal cats for analysis of cTnI.

RESULTS

Measured values of purified cTnI closely matched calculated concentrations (r(2)=0.997) and recovery ranged from 107-164%. Intraassay precision was 2.76+/-1.20% and interassay precision was 8.50+/-4.19%. The dogs were 4.8+/-3.1 years and 24.4+/-11.2kg (27 Mc, 19 Fs, 5 M, 4 F). The cats were 4.9+/-2.8 years and 5.1+/-1.19kg (36 Mc, 22 Fs). The median and range (5th and 95th percentile) of cTnI for dogs were <0.05ng/mL (<0.05-0.12). The median cTnI for cats was <0.05ng/mL, as was the range, because only 3 cats (the upper 5% of the population) had detectable cTnI concentrations. The lower limit of detection for this assay is 0.05ng/mL.

CONCLUSIONS

This study provides reference ranges for cTnI in dogs and cats using the Triage Meter((R)), an affordable bedside analyzer. The availability of reference ranges for this machine may increase clinical use and research of this marker in veterinary medicine.

Dosagem sérica de troponina I em cães com desnível do segmento ST utilizando quimioluminescência

Com o intuito de verificar algum dano nas células do miocárdio, utilizaram-se 38 cães, 20 com traçado eletrocardiográfico normal, grupo 1, e 18 com desníveis do segmento ST, grupo 2, em registro na derivação II, velocidade de 50mm/s e sensibilidade N (1mV=1cm). No grupo 1, a dosagem sérica da troponina I (cTnI) destinou-se à obtenção dos valores referenciais (ng/mL) que seriam confrontados com os obtidos no grupo 2. A média e o desvio-padrão foram, respectivamente, 0,16ng/mL e 0,11ng/mL e 0,20ng/mL e 0,11ng/mL, nos grupos 1 e 2. A cTnI não apresentou evidências de associação com idade, massa corpórea, creatinafosfoquinase total e potássio nos dois grupos. Não houve diferenças significativas nos valores de cTnI entre os grupos. Conclui-se que é possível a utilização do kit de ensaio imunométrico quimioluminescente humano para a espécie canina e que a hipóxia-isquemia, revelada pelo desnível do segmento ST não acarreta dano miocárdico ou este é mínimo e indetectável.

Comparison of plasma cardiac troponin I concentrations among dogs with cardiac hemangiosarcoma, noncardiac hemangiosarcoma, other neoplasms, and pericardial effusion of nonhemangiosarcoma origin

OBJECTIVE

To determine whether plasma cardiac troponin I (cTnl) concentrations can be used to identify cardiac involvement in dogs with hemangiosarcoma, exclude cardiac hemangiosarcoma in dogs with noncardiac hemangiosarcoma, and identify cardiac hemangiosarcoma in dogs with pericardial effusion.

DESIGN

Cohort study.

ANIMALS

57 dogs (18 with confirmed [5 dogs] or suspected [13] cardiac hemangiosarcoma, 14 with confirmed hemangiosarcoma involving sites other than the heart [noncardiac hemangiosarcoma], 10 with pericardial effusion not caused by hemangiosarcoma, and 15 with noncardiac nonhemangiosarcoma neoplasms).

PROCEDURES

Plasma cTnl concentration was measured, and thoracic radiography, abdominal ultrasonography, and echocardiography were performed in each dog. The cTnl concentration was compared among groups.

RESULTS

Median plasma cTnl concentration in dogs with cardiac hemangiosarcoma was significantly higher than the concentration in each of the other groups. A plasma cTnl concentration > 0.25 ng/mL could be used to identify cardiac involvement in dogs with hemangiosarcoma at any site (sensitivity, 78%; specificity, 71 %). A plasma cTnl concentration > 0.25 ng/mL could be used to identify cardiac hemangiosarcoma in dogs with pericardia effusion (sensitivity, 81%; specificity, 100%).

CONCLUSIONS AND CLINICAL RELEVANCE

The median plasma cTnl concentration was higher in dogs with cardiac hemangiosarcoma, compared with the median concentration in dogs with hemangiosarcoma at other sites, dogs with other neoplasms, and dogs with pericardial effusion not caused by hemangiosarcoma. The plasma cTnl concentration may be used to identify cardiac involvement in dogs with hemangiosarcoma and to identify cardiac hemangiosarcoma in dogs with pericardial effusion.

Serum cardiac troponin I concentration in dogs with precapillary and postcapillary pulmonary hypertension

BACKGROUND

Pulmonary hypertension (PH) is a disease condition leading to right-sided cardiac hypertrophy and, eventually, right-sided heart failure. Cardiac troponin I (cTnI) is a circulating biomarker of cardiac damage.

HYPOTHESIS

Myocardial damage can occur in dogs with precapillary and postcapillary PH.

ANIMALS

One hundred and thirty-three dogs were examined: 26 healthy controls, 42 dogs with mitral valve disease (MVD) without PH, 48 dogs with pulmonary hypertension associated with mitral valve disease (PH-MVD), and 17 dogs with precapillary PH.

METHODS

Prospective, observational study. Serum cTnI concentration was measured with a commercially available immunoassay and results were compared between groups.

RESULTS

Median cTnI was 0.10 ng/mL (range 0.10-0.17 ng/mL) in healthy dogs. Compared with the healthy population, median serum cTnI concentration was increased in dogs with precapillary PH (0.25 ng/mL; range 0.10-1.9 ng/mL; P < .001) and in dogs with PH-MVD (0.21 ng/mL; range 0.10-2.10 ng/mL; P < .001). Median serum cTnI concentration of dogs with MVD (0.12 ng/mL; range 0.10-1.00 ng/mL) was not significantly different compared with control group and dogs with PH-MVD. In dogs with MVD and PH-MVD, only the subgroup with decompensated PH-MVD had significantly higher cTnI concentration compared with dogs with compensated MVD and PH-MVD. Serum cTnI concentration showed significant modest positive correlations with the calculated pulmonary artery systolic pressure in dogs with PH and some echocardiographic indices in dogs with MVD and PH-MVD.

CONCLUSIONS AND CLINICAL IMPORTANCE

Serum cTnI is high in dogs with either precapillary and postcapillary PH. Myocardial damage in dogs with postcapillary PH is likely the consequence of increased severity of MVD.

Serum cardiac troponin I concentration in dogs with ehrlichiosis

BACKGROUND

Ehrlichiosis is a multisystemic disease with the potential to cause cardiomyocyte injury in naturally infected dogs.

HYPOTHESIS

Myocardial injury occurs in dogs infected with Ehrlichia canis.

ANIMALS

One-hundred and ninety-four dogs from Brazil with clinical and laboratory abnormalities indicative of ehrlichiosis. Sixteen healthy dogs served as controls.

METHODS

Electrocardiogram, echocardiogram, noninvasive blood pressure measurement, and serum cardiac troponin I (cTnI) concentrations were evaluated. Serologic assays and PCR determined the exposure and infection status for E. canis, Anaplasma spp., Babesia canis vogeli, Bartonella spp., Borrelia burgdorferi, Dirofilaria immitis, Ehrlichia chaffeensis, Ehrlichia ewingii, Leishmania chagasi, and spotted-fever group Rickettsia. Dogs were assigned to groups according to PCR status: E. canis infected, infected with other vector-borne organisms, sick dogs lacking PCR evidence for infection, and healthy controls.

RESULTS

E. canis-infected dogs had higher serum cTnI concentrations than controls (median: 0.04 ng/dL; range 0.04-9.12 ng/dL; control median: 0.04 ng/dL; range: 0.04-0.10 ng/dL; P= .012), and acute E. canis infection was associated with myocardial injury (odds ratio [OR]: 2.67, confidence interval [CI] 95%: 1.12-6.40, P= .027). Severity of anemia was correlated with increased risk of cardiomyocyte damage (r= 0.84, P< .001). Dogs with clinical signs of systemic inflammatory response syndrome (SIRS) were at higher risk for myocardial injury than were other sick dogs (OR: 2.55, CI 95%: 1.31-4.95, P= .005).

CONCLUSIONS AND CLINICAL IMPORTANCE

Acute infection with E. canis is a risk factor for myocardial injury in naturally infected Brazilian dogs. Severity of anemia and SIRS might contribute to the pathophysiology of myocardial damage.

Cardiac troponin I: evaluation of a biomarker for the diagnosis of heart disease in the dog

OBJECTIVES

To assess the value of measuring blood levels of the myocardial protein cardiac troponin I (cTnl) in the diagnosis of congenital and acquired heart disease in the dog and in the evaluation of the severity of heart failure.

METHODS

Serum samples obtained from healthy dogs (n = 26) and from dogs diagnosed with a variety of congenital and acquired heart conditions (n = 35) were assayed for cTnl concentration using an automated immunoassay method. Results were also analysed according to the degree of heart failure as assessed using the International Small Animal Cardiac Health Council's scheme.

RESULTS

Healthy dogs had very low or undetectable blood cTnl levels, as did dogs with congenital heart disease. However, cTnl levels were significantly elevated in dogs with acquired mitral valve disease, dilated cardiomyopathy and pericardial effusion. Blood cTnl levels also varied with severity of heart failure.

CLINICAL SIGNIFICANCE

Measurement of blood cTnl levels may be a useful aid in the diagnosis of dogs with suspected heart disease and in indicating the severity of heart failure.