Multi-centered investigation of a point-of-care NT-proBNP ELISA assay to detect moderate to severe occult (pre-clinical) feline heart disease in cats referred for cardiac evaluation

Investigation of α-Klotho Concentrations in Serum of Cats Affected by Hypertrophic Cardiomyopathy

Being involved in various physiological and pathophysiological mechanisms (ageing, kidney damage, cardiovascular diseases, etc.), Klotho is a parameter of increasing interest. Studies in veterinary medicine are still rare, but it is exciting to find out whether the findings obtained can be transferred to animals. The aim of this study was therefore to investigate Klotho in cats. This study addressed α-Klotho concentrations in the serum of two groups of cats: one diseased group affected by hypertrophic cardiomyopathy (n = 27) and one healthy control group (n = 35). α-Klotho concentrations in serum were measured using an ELISA. The results were evaluated in the context of several echocardiographic measurement parameters in the diseased group. No significant difference between α-Klotho concentrations in the two groups was found. A slight negative correlation was found between α-Klotho concentrations and the relation of left atrium/aorta (La/Ao) in the diseased group. Gaining initial information on α-Klotho in cats, it was not possible to draw definite conclusions concerning cardiomyopathies in this species. The assessment of Klotho should be considered in terms of its broad implications in disease processes, but it is also recommended to focus on specific disease features. Both approaches might be promising as possible applications of Klotho in veterinary medicine.

A self-driven, microfluidic, integrated-circuit biosensing chip for detecting four cardiovascular disease biomarkers

Cardiovascular diseases (CVDs) claimed the lives of nearly 21 million people worldwide in 2021, accounting for 30% of global deaths. However, one in five CVD patients is unaware that they have the disease, emphasizing the need for accurate biomarker monitoring. Herein we developed an integrated microfluidic system (IMS) for rapid quantification of four CVD biomarkers, including N-terminal pro B-type natriuretic peptide (NT-proBNP), fibrinogen, cardiac troponin I (cTnI), and C-reactive protein (CRP)- via aptamer-coated interdigitated electrodes (IDE) with integrated circuits (IC) and a self-driven IMS for sample treatment. The device was composed of plasma filtration, metering, and fluidic delay modules, and the former could extract 45% of plasma from a 20-μL blood sample; the metering module could quantify 5 μL of plasma within 90 s. Subsequently, the plasma was transported to a detection chamber, where IC-based IDE sensors made measurements within 5 min. The entire 15-min process allowed us to evaluate biomarkers across a wide dynamic range: NT-proBNP (0.1-10,000 pg/mL), fibrinogen (50-1,000 mg/dL), cTnI (0.1-10,000 pg/mL), and CRP (0.5-9 mg/L). Given that spiked blood samples were measured with reasonable accuracy (>80%), the IMS could see utility in CVD risk assessment and personalized medicine.

MORBIDITY AND MORTALITY OF BINTURONGS (ARCTICTIS BINTURONG) IN UNITED STATES ZOOLOGICAL INSTITUTIONS (1986-2019)

Veterinary literature on diseases in binturong (Arctictis binturong) is often limited to case series or reports without population-level information. Morbidity and mortality data were collected from North American institutions through survey completion or submission of medical records. Responses included information about 74 individuals (37 males, 30 females, and 7 unknown neonates) representing 22 institutions, from 1986 to 2019. Antemortem data were available from 39 individuals, and postmortem data were available from 53 individuals. Eighteen individuals had both antemortem and postmortem records available. Age (mean ± SD) at death for adults (n = 41) was 15.2 ± 4.3 yr. Morbidity events were summarized by affected organ system; 160 events were reported. The systems with the most frequently reported events were gastrointestinal (33%; 53/160), integumentary (19%; 31/160), urinary (12%; 20/160), and musculoskeletal (19 [12%] of 160). Excluding neonates, primary causes of mortality included neoplasia (51%; 21/41), infectious or inflammatory diseases (24%; 10/41), and cardiovascular disease (17%; 7/41). Neoplasms (51%; 21/41) confirmed on histopathology included renal adenocarcinoma (47%; 10/21); mammary carcinoma (14%; 3/21); pancreatic islet cell carcinoma (2 [10%] of 21); and single instances of multicentric lymphoma, uterine carcinoma, and submucosal urethral adenoma. There were three additional cases of presumed neoplasia without histopathologic confirmation; masses were detected in the liver, heart base, and pancreas. Metastases were reported in 15 (71%) of 21 neoplasms. Although neoplasia and cardiovascular disease were common causes of mortality, they were rarely diagnosed antemortem. Neoplasia was often malignant and generally diagnosed after metastasis. Preventive medicine protocols with improved renal and cardiovascular evaluation are warranted and may result in earlier detection of subclinical disease in binturong.

Should we be screening cats for cardiomyopathy? If so, how?

Occult feline hypertrophic cardiomyopathy (HCM) can result in unexpected sudden death or congestive heart failure (CHF) following routine interventions such as anesthesia, fluid administration, or, potentially, administration of corticosteroids. Consequently, clinicians would like to be able to screen at-risk cats to detect occult HCM and either avoid the risky intervention or attempt to reduce the risk of death or CHF. Currently, the feline N-terminal-proBrain natriuretic peptide test is the only potential screening test for detecting occult HCM. However, some cardiologists have pointed out the poor sensitivity of the test precludes its use as a screening test. This interpretation appears somewhat flawed. Using the current rapid test will allow clinicians to correctly identify half of the cats with moderate-to-severe occult HCM. A small number of cats without HCM will also test positive, necessitating an ultimately needless echocardiographic evaluation to demonstrate their disease-free status. However, the low prevalence of HCM in the general cat population and the apparently much lower rate of adverse events than would be predicted brings into question whether clinicians should bother screening. Therefore, until a more sensitive and accurate screening test becomes available, clinicians will have to decide for themselves whether identifying half of the at-risk cats of sudden death and CHF with this test is better than identifying none of them.

The Feline Cardiomyopathies: 2. Hypertrophic cardiomyopathy

Practical relevance:

Hypertrophic cardiomyopathy (HCM) is the most common form of feline cardiomyopathy observed clinically and may affect up to approximately 15% of the domestic cat population, primarily as a subclinical disease. Fortunately, severe HCM, leading to heart failure or arterial thromboembolism (ATE), only occurs in a small proportion of these cats.

Patient group:

Domestic cats of any age from 3 months upward, of either sex and of any breed, can be affected. A higher prevalence in male and domestic shorthair cats has been reported.

Diagnostics:

Subclinical feline HCM may or may not produce a heart murmur or gallop sound. Substantial left atrial enlargement can often be identified radiographically in cats with severe HCM. Biomarkers should not be relied on solely to diagnose the disease. While severe feline HCM can usually be diagnosed via echocardiography alone, feline HCM with mild to moderate left ventricular (LV) wall thickening is a diagnosis of exclusion, which means there is no definitive test for HCM in these cats and so other disorders that can cause mild to moderate LV wall thickening (eg, hyperthyroidism, systemic hypertension, acromegaly, dehydration) need to be ruled out.

Key findings:

While a genetic cause of HCM has been identified in two breeds and is suspected in another, for most cats the cause is unknown. Systolic anterior motion of the mitral valve (SAM) is the most common cause of dynamic left ventricular outflow tract obstruction (DLVOTO) and, in turn, the most common cause of a heart murmur with feline HCM. While severe DLVOTO is probably clinically significant and so should be treated, lesser degrees probably are not. Furthermore, since SAM can likely be induced in most cats with HCM, the distinction between HCM without obstruction and HCM with obstruction (HOCM) is of limited importance in cats. Diastolic dysfunction, and its consequences of abnormally increased atrial pressure leading to signs of heart failure, and sluggish atrial blood flow leading to ATE, is the primary abnormality that causes clinical signs and death in affected cats. Treatment (eg, loop diuretics) is aimed at controlling heart failure. Preventive treatment (eg, antithrombotic drugs) is aimed at reducing the risk of complications (eg, ATE).

Conclusions:

Most cats with HCM show no overt clinical signs and live a normal or near-normal life despite this disease. However, a substantial minority of cats develop overt clinical signs referable to heart failure or ATE that require treatment. For most cats with clinical signs caused by HCM, the long-term prognosis is poor to grave despite therapy.

Areas of uncertainty:

Genetic mutations (variants) that cause HCM have been identified in a few breeds, but, despite valiant efforts, the cause of HCM in the vast majority of cats remains unknown. No treatment currently exists that reverses or even slows the cardiomyopathic process in HCM, again despite valiant efforts. The search goes on.

Clinical findings associated with N-terminal pro-B-type natriuretic peptide measurement in dogs and cats attending first opinion veterinary practices

BACKGROUND

Clinical findings associated with N-terminal pro-B-type natriuretic peptide (NT-proBNP) measurement in dogs and cats in primary practice, and their relevance to published measurement indications, have not been described.

METHODS

Using electronic health record data collected by the Small Animal Veterinary Surveillance Network, appointments in which NT-proBNP was measured were identified using keyword-based text filtering. For these appointments, clinical findings were manually identified from each patient's clinical narrative (CN) and their frequencies described.

RESULTS

CNs of 3510 appointments (357 dogs and 257 cats) from 99practices were evaluated. The most frequently recorded clinical findings in dogs were: heart murmur (n = 147, 41.2% (95% confidence interval (CI) = 36.1%-46.3%), coughing (n = 83, 23.2% (95% CI = 18.8%-27.6%)) and panting (n = 58, 16.2% (95% CI = 12.4%-20.0%)) and in cats: heart murmur (n = 143, 55.6% (95% CI = 49.5%-61.7%)), suspected thromboembolism (n = 88, 34.2% (95% CI = 28.4%-40.0%)) and weight loss (n = 53, 20.6% (95% CI = 15.7%-25.5%)). Dyspnoea and tachypnoea were infrequently reported in dogs (n = 29, 8.1% (95% CI = 5.3%-10.9%) and n = 21, 5.9% (95% CI = 3.5%-8.3%), respectively) and cats (n = 26, 10.1% (95% CI = 6.4%-13.8%) and n = 36, 14.0% (95% CI = 9.8%-18.2%), respectively).

CONCLUSION

Clinical findings referable to cardiac disease were recorded contemporaneously with NT-proBNP measurement and suggested both published and other indications (coughing (in dogs and cats), and serial measurements and thromboembolism (in cats)) for testing.

Point-of-care N-terminal pro B-type natriuretic peptide assay to screen apparently healthy cats for cardiac disease in general practice

Background

Point‐of‐care (POC) N‐terminal pro B‐type natriuretic peptide (NT‐proBNP) ELISA test has been evaluated for screening cats for cardiac disease in the referral veterinary setting but less is known about its use in general practice (GP).

Objectives

To evaluate the diagnostic utility of a POC NT‐proBNP ELISA in cats seen in GPs.

Animals

Two hundred and seventeen apparently healthy cats from 21 GPs.

Methods

This was a prospective, cross‐sectional study. Cardiac auscultation and POC NT‐proBNP ELISA were done by veterinarians at their GPs. After enrollment at GPs, cats were sent to a cardiology referral hospital for cardiac auscultation and echocardiographic diagnosis. Results were interpreted based on whether cats had normal or abnormal echocardiographic findings.

Results

Point‐of‐care NT‐proBNP ELISA results differentiated cats in the abnormal group from those in the normal group with a sensitivity of 43%, specificity of 96%. In cats with a heart murmur at GPs, POC NT‐proBNP ELISA results differentiated cats in the abnormal group from those in the normal group with a sensitivity of 71% and a specificity of 92%.

Conclusion and Clinical Importance

In apparently healthy cats in GPs, positive POC NT‐proBNP results are associated with heart disease, warranting an echocardiogram, but negative results do not reliably exclude heart disease. These results suggest POC NT‐proBNP is not an effective screening test for apparently healthy cats in GPs, although its performance is improved if it is used only in cats that have a heart murmur.

Reference intervals for radiographic, echocardiographic and N-terminal pro B-type natriuretic peptide values in healthy kittens

OBJECTIVES

Assessment of heart size in kittens is important, and there is a need for reference intervals (RIs) to prevent misinterpretation of cardiomegaly in this patient population. The purpose of this study was to generate RIs for echocardiographic and radiographic quantification of cardiac size in healthy kittens.

METHODS

In total, 88 kittens aged 6-16 weeks were enrolled in this study. Physical examination, and radiographic and echocardiographic evaluations were performed without sedation. Thoracic radiographs and echocardiographic images were measured to establish RIs for vertebral heart score (VHS), cardiac thoracic ratio (CTR) and multiple echocardiographic variables. N-terminal pro B-type natriuretic peptide (NT-proBNP) was measured. Statistical correlations between echocardiographic parameters and age, body weight and sex were all evaluated and RIs were generated.

RESULTS

Low-grade heart murmurs were appreciated in 26/88 kittens (29.5%). Kittens had a median VHS of 9.5 vertebrae (95% RI 8.0-10.9) and a median CTR of 67.2% (95% RI 54.4-79.8%). Measured NT-proBNP levels were comparable to healthy adult cats with a median of 31 pmol/l (upper reference limit 75 pmol/l). Multiple moderate-to-strong correlations between body weight and age with various echocardiographic parameters were observed and allometric scaling was performed for body weight. RIs for echocardiographic parameters were generated based on patient weight using allometric scaling formulas. Tricuspid valve regurgitation was a common finding and was present in 37.5% (n = 33) of the kittens.

CONCLUSIONS AND RELEVANCE

This study establishes RIs for thoracic radiograph assessment, echocardiography and cardiac biomarkers in kittens, which fills a critical gap in the veterinary literature. The VHS reported in this study is higher than previously reported for adult cats.

Updates on Laboratory Evaluation of Feline Cardiac Diseases

Laboratory tests can be altered in cardiovascular diseases and the investigation of specific tests or biomarkers may provide additional information about myocardial damage. Traditional laboratory tests, such as cell blood count, serum biochemistry, and coagulation, can be useful in investigating patients, but are not specific. However, markers like Troponin and Natriuretic Peptides may possibly furnish further data on myocardium damage and can be used in both studying and monitoring cats with cardiac disease. Moreover, the evaluation of the thyroid profile is very important as hyperthyroid cats concomitant cardiovascular diseases are very common and they can also be a direct consequence of endocrinopathy. The purpose of this manuscript is to provide the widest possible overview of what is present in the literature about the feline clinical pathology of heart diseases through a rational division of the main alterations of traditional tests and biomarkers.

Occurrences of heart disease in apparently healthy cats in Klang Valley, Malaysia

Objective

Annual health screening inclusive of heart workup is recommended for the detection of heart diseases, especially in asymptomatic patients (no clinical signs). This study determined the occurrences of the common heart disease and the risk factors in apparently healthy cats.

Materials and methods

This prospective study that screened 59 healthy cats and the status of the heart were evaluated based on a combination of findings from physical examination, electrocardiography, blood pressure measurement, routine blood test, urinalysis, and total thyroid level.

Results

Approximately 40.7% (n = 24/59) of the apparently healthy cats were diagnosed with heart disease hypertrophic cardiomyopathy (62.5%) remains to be the most commonly diagnosed. The mean age was 4.9-year old (age range, 7-month-old to 19-year-old). The prevalence was higher in males (45.0%; n = 17/38) cats, especially the domestic shorthairs (46.0%; n = 11/24). Among the healthy cats with vertebral heart scale (VHS) > 8.0, only 52% (n = 12/23) of them were diagnosed with cardiomyopathy. However, 33% (n = 12/36) of the cats with normal VHS ≤ 7.9 were diagnosed with heart disease. Consistently, all healthy cats with abnormal heart sounds were diagnosed with heart disease. About 31.4% (n = 16/51) of these cats with typical heart sound had cardiomyopathy too.

Conclusion

The occurrence of cardiomyopathy in apparently healthy cats has no association with the patient's age, sex, and VHS, except for the heart sound. Echocardiography remains the best diagnostic tool, as normal heart size and normal heart sound do not exclude cardiomyopathy in this group of apparently healthy cats.

Focused cardiac ultrasound and point-of-care NT-proBNP assay in the emergency room for differentiation of cardiac and noncardiac causes of respiratory distress in cats

OBJECTIVE

To assess the accuracy of focused cardiac ultrasound (FOCUS) and point-of-care N-terminal proBNP assay in the emergency setting for differentiation of cardiac from noncardiac causes of respiratory distress in cats.

DESIGN

Prospective diagnostic accuracy study between 2014 and 2016.

SETTING

Emergency room at an urban university teaching hospital.

ANIMALS

Forty-one client-owned cats presenting for evaluation of respiratory distress.

INTERVENTIONS

Emergency clinicians made an initial diagnosis of noncardiac or cardiac cause of respiratory distress based on physical examination (PE) findings and history. The diagnoses were updated after performing FOCUS and point-of-care N-terminal B-type natriuretic peptide (POC-BNP). Reference standard diagnosis was determined by agreement of a board-certified cardiologist and critical care specialist with access to subsequent radiographs and echocardiograms.

MEASUREMENTS AND MAIN RESULTS

Forty-one cats were enrolled. Three cats with incomplete data and 1 cat with an uncertain reference standard diagnosis were excluded. The remaining 37 cats were used for analysis: 21 cardiac and 16 noncardiac cases. The ratio of left atrial to aortic root diameter (LA:Ao) measured by FOCUS was significantly correlated with LA:Ao measured by echocardiography (R = 0.646, P < 0.0001). Emergency clinicians correctly diagnosed 27 of 37 (73.0%), yielding a PE positive percent agreement = 76.2% (95% CI, 52.8-91.8%) and negative percent agreement = 68.8% (95% CI, 41.3-89.0%). Five noncardiac and 5 cardiac cats were misdiagnosed. Post FOCUS, overall percent agreement improved to 34 of 37 (91.9%), with positive percent agreement = 95.2% (95% CI, 76.2-99.9%) and negative percent agreement = 87.5% (95% CI, 61.7-98.5%). The POC-BNP yielded an overall percent agreement = 32/34 (94.1%), positive percent agreement = 100% (95% CI, 82.4-100.0%), and negative percent agreement = 86.7% (95% CI, 59.5-98.3%) in differentiating cardiac versus noncardiac cases.

CONCLUSIONS

FOCUS evaluation of basic cardiac structure and LA:Ao by trained emergency clinicians improved accuracy of diagnosis compared to PE in cats with respiratory distress. FOCUS and POC-BNP are useful diagnostics in the emergent setting.

Accuracy of methods for diagnosing heart diseases in cats

Aim

This study aimed to determine the accuracy of the current methods for diagnosing heart diseases in cats.

Materials and Methods

The data of 58 cats were retrospectively retrieved. Cats were classified into two groups: Thirty-eight cats with heart diseases and 20 healthy cats. Echocardiography was the gold standard method for diagnosing heart disease. The results of seven methods were retrieved: (1) Vertebral heart score (VHS) with a cutoff value >8, (2) VHS with a cutoff value >8.5, (3) multiplication of cardiac length (L) and width (W), (4) multiplication of cardiac L and W divided by the L of the fourth sternal thoracic bone, (5) N-terminal Pro-B-type natriuretic peptide (NT-proBNP) point-of-care test, (6) subjective ultrasonographic assessment of the left atrial size, and (7) subjective radiographic assessment of the left atrial size. Cross-tabulation was used to calculate the sensitivity, specificity, accuracy, positive predictive value, and negative predictive value for each test. This study found that using the NT-proBNP point-of-care test was optimal in the diagnosis of cats with heart disease.

Results

The subjective ultrasonographic assessment of the left atrial size was good for diagnosing hypertrophic cardiomyopathy and congestive heart failure.

Conclusion

This study showed that the more tests used, the higher the reliability of the diagnosis.

ACVIM consensus statement guidelines for the classification, diagnosis, and management of cardiomyopathies in cats

Cardiomyopathies are a heterogeneous group of myocardial disorders of mostly unknown etiology, and they occur commonly in cats. In some cats, they are well‐tolerated and are associated with normal life expectancy, but in other cats they can result in congestive heart failure, arterial thromboembolism or sudden death. Cardiomyopathy classification in cats can be challenging, and in this consensus statement we outline a classification system based on cardiac structure and function (phenotype). We also introduce a staging system for cardiomyopathy that includes subdivision of cats with subclinical cardiomyopathy into those at low risk of life‐threatening complications and those at higher risk. Based on the available literature, we offer recommendations for the approach to diagnosis and staging of cardiomyopathies, as well as for management at each stage.

Effect of feline characteristics on plasma N-terminal-prohormone B-type natriuretic peptide concentration and comparison of a point-of-care test and an ELISA test

BACKGROUND

Increased plasma concentration of N-terminal-prohormone B-type natriuretic peptide (NT-proBNP) can be detected in cats with cardiac disease. Potential effects of feline characteristics on NT-proBNP concentration may influence clinical usefulness.

OBJECTIVES

To evaluate potential effects of feline characteristics on NT-proBNP plasma concentration and to compare NT-proBNP plasma concentrations in healthy cats with results in hypertrophic cardiomyopathy (HCM) cats with or without left atrial enlargement (LAE) using an ELISA and a point-of-care test (POCT), and assess if POCT results reflect ELISA results.

ANIMALS

One hundred healthy cats of 3 breeds and 39 HCM cats were included.

METHODS

Diseases other than HCM were excluded by physical examination, blood pressure measurement, echocardiography, hematology, and serum biochemistry.

RESULTS

Higher NT-proBNP concentrations were found in males than in females in healthy (P = .005) and in HCM cats (P = .0021), but breed had no effect on NT-proBNP concentrations. Using ≥100 pmol/L as a cutoff for abnormal samples, ELISA and POCT had similar sensitivity (SE; 72 and 74%) and specificity (SP; 97 and 98%) for detecting cats with HCM, cats with HCM and LAE (SE, both 100%; SP, 97 versus 98%), and cats with HCM without LAE (SE, both 69%; SP, 97 versus 98%), respectively, when compared to healthy cats.

CONCLUSIONS AND CLINICAL IMPORTANCE

Breed had no effect on plasma NT-proBNP concentrations, but higher concentrations were found in male than in female cats. The ELISA and POCT had similar SE and SP for detecting HCM. Both tests could identify all HCM cats with LAE but not all HCM cats without LAE.

The use of focused cardiac ultrasound to screen for occult heart disease in asymptomatic cats

Background

Focused cardiac ultrasound (FCU) helps detect occult heart disease in human patients.

Hypothesis

Focused cardiac ultrasound by a nonspecialist practitioner (NSP) will increase the detection of occult heart disease in asymptomatic cats compared with physical examination and ECG.

Animals

Three hundred forty‐three client‐owned cats: 54 excluded and 289 analyzed.

Methods

Multicenter prospective cohort study. Twenty‐two NSPs were trained to perform FCU. Cats without clinical signs of heart disease were recruited, and NSPs performed the following in sequential order: physical examination, ECG, FCU, and point‐of‐care N‐terminal pro‐B‐type natriuretic peptide assay (POC‐BNP). After each step, NSPs indicated yes, no, or equivocal as to whether they believed heart disease was present. The level of agreement between the NSP diagnosis and a blinded cardiologist's diagnosis after echocardiogram was evaluated using Cohen's kappa test.

Results

Cardiologist diagnoses included 148 normal cats, 102 with heart disease, and 39 equivocal ones. Agreement between NSP and cardiologist was slight after physical examination (kappa 0.253 [95% CI, 0.172‐0.340]), did not increase after ECG (0.256 [0.161‐0.345]; P = .96), increased after FCU (0.468 [0.376‐0.558]; P = .002), and the level of agreement was similar after POC‐BNP (0.498 [0.419‐0.580]; P = .67). In cats with mild, moderate, and marked occult heart disease, the proportion of cats having a NSP diagnosis of heart disease after FCU was 45.6%, 93.1%, and 100%, respectively.

Conclusions and Clinical Importance

Focused cardiac ultrasound performed by NSPs increased the detection of occult heart disease, especially in cats with moderate to marked disease. Focused cardiac ultrasound appears to be a feasible and useful tool to assist NSPs in the detection of heart disease in cats.

Evaluation of a sensitive cardiac troponin I assay as a screening test for the diagnosis of hypertrophic cardiomyopathy in cats

Background

Hypertrophic cardiomyopathy (HCM) is the most common cardiac disease in cats. However, most cats are not diagnosed until they develop congestive heart failure, arterial thromboembolism (ATE), or sudden cardiac death. Thus, an affordable screening test for early detection of HCM is desirable.

Hypothesis/Objectives

Evaluation of a sensitive cardiac troponin I (cTnI) assay as a screening test for HCM in cats and determination of a cutoff for its early detection.

Animals

One hundred sixty‐six client‐owned cats (male, n = 97) of various breeds were evaluated and classified using echocardiography as being healthy (n = 87), equivocal (n = 15), or having HCM (mild, n = 16; moderate, n = 10; severe, n = 34) or ATE (n = 4).

Methods

All cats were prospectively evaluated by echocardiography, and serum cTnI concentration was determined using the currently most sensitive assay (Siemens ADVIA Centaur TnI‐Ultra).

Results

The median cTnI concentration was significantly different between study groups (P < .000001). A cutoff of 0.06 ng/mL provided good discrimination between healthy cats and cats with HCM (sensitivity, 91.7%; specificity, 95.4%; area under the curve [AUC], 0.95; 95% confidence interval [CI], 0.899‐0.978). Even for asymptomatic cats with HCM, sensitivity and specificity for a cutoff of >0.06 ng/mL remained high at 87.8% and 95.4%, respectively (AUC, 0.93; 95% CI, 0.864‐0.964).

Conclusions and clinical importance

Cardiac troponin I can be used as a sensitive and specific screening test for the diagnosis of HCM in otherwise healthy cats (cutoff, >0.06 ng/mL). However, echocardiography is needed to confirm the diagnosis.

Ultrasensitive Photoelectrochemical Biosensing Platform for Detecting N-Terminal Pro-brain Natriuretic Peptide Based on SnO2/SnS2/mpg-C3N4 Amplified by PbS/SiO2

A sandwich-type photoelectrochemical (PEC) immunosensor for detecting N-terminal pro-brain natriuretic peptide (NT-proBNP) was constructed on the basis of SnO₂/SnS₂/mpg-C₃N₄ nanocomposites and PbS/SiO₂, with the former as a photoactive matrix and the latter as an efficient quencher. SnO₂/SnS₂/mpg-C₃N₄ was synthesized via in situ growth of SnO₂ and SnS₂ on mesoporous graphene like C₃N₄ nanocomposites (mpg-C₃N₄). Specifically, SnO₂/SnS₂/mpg-C₃N₄ exhibited intense PEC signal responses, which are tens of times stronger than its each single component. Because of its superior performance, SnO₂/SnS₂/mpg-C₃N₄ was applied as a photoactive matrix and signal indicator for fabricating PEC immunosensor. Interestingly, the excellent PEC signals from SnO₂/SnS₂/mpg-C₃N₄ could be reduced severely with the addition of PbS/SiO₂. Hence, the secondary antibody bioconjugates (PbS/SiO₂-Ab₂) were prepared as an efficient quencher. The mechanism of the quench reaction was further discussed in detail. On the basis of the interaction between the matrix and the quencher, the NT-proBNP immunosensor was fabricated and a wide linear range of 0.1 pg·mL^-1 to 50 ng·mL^-1 was obtained with a low detection limit of 0.05 pg·mL^-1. Additionally, the PEC immunosensor manifested good stability, reproducibility, and selectivity, which could underlie robust platforms for detecting multitudinous biomarkers or other targets of interest.

AAFP Feline Anesthesia Guidelines

AIM

The overarching purpose of the AAFP Anesthesia Guidelines (hereafter referred to as the 'Guidelines') is to make anesthesia and sedation safer for the feline patient. Scope and accessibility: It is noteworthy that these are the first exclusively feline anesthesia guidelines authored by an expert panel, making them particularly useful as an extensively referenced, practical resource for veterinary practice teams. Because much of the key content is presented in tabular or visual format, the Guidelines have a high level of accessibility and convenience that invites regular usage. While the recommendations in the Guidelines focus primarily on client-owned cats, the content is also applicable to community-sourced animals with an unknown medical history.

Assessment of a bedside test for N-terminal pro B-type natriuretic peptide (NT-proBNP) to differentiate cardiac from non-cardiac causes of pleural effusion in cats

Background

Cats with pleural effusion represent common emergencies in small animal practice. The aim of this prospective study was to investigate the diagnostic ability of a point-of-care ELISA (POC-ELISA) for the measurement of N-terminal pro B-type natriuretic peptide (NT-proBNP) to differentiate cardiac from non-cardiac disease in cats with pleural effusion. The sample material for use of this rapid test was either plasma or diluted pleural effusion.

Twenty cats with moderate to severe pleural effusion were prospectively recruited. The cats were grouped into two groups, with or without congestive heart failure (CHF; N-CHF), after complete work-up. Blood and effusion were collected in EDTA tubes. Plasma and pleural effusion supernatants were transferred into stabilizer tubes and frozen. POC-ELISA for NT-proBNP was performed with plasma and diluted effusion (1:1). Quantitative NT-proBNP measurement was performed in plasma and diluted and undiluted effusions.

Results

Six cats were assigned to the CHF group. Of the 14 cats in the N-CHF group, 6 had concurrent cardiac abnormalities that were not responsible for the effusion. For the detection of CHF, the test displayed respective sensitivities and specificities of 100% and 79% in plasma and 100% and 86% in diluted pleural fluid. Receiver operating characteristic (ROC) analysis for quantitative NT-proBNP measurement of plasma and diluted and undiluted pleural effusions displayed areas under the curve of 0.98, sensitivities of 100% and specificities of 86%. The optimum cut-off was calculated at 399 pmol/l in plasma and 229 pmol/l in the diluted effusion and 467 pmol/l in the undiluted effusion.

Conclusions

POC-ELISA for NT-proBNP in both plasma and diluted pleural effusion was suitable to differentiate cardiac from non-cardiac causes of feline pleural effusion. According to our results, use of pleural effusion is feasible, but dilution of the effusion before measurement seems to improve specificity.

Electronic supplementary material

The online version of this article (10.1186/s12917-017-1319-6) contains supplementary material, which is available to authorized users.

Assessment of a bedside test for N-terminal pro B-type natriuretic peptide (NT-proBNP) to differentiate cardiac from non-cardiac causes of pleural effusion in cats

BACKGROUND

Cats with pleural effusion represent common emergencies in small animal practice. The aim of this prospective study was to investigate the diagnostic ability of a point-of-care ELISA (POC-ELISA) for the measurement of N-terminal pro B-type natriuretic peptide (NT-proBNP) to differentiate cardiac from non-cardiac disease in cats with pleural effusion. The sample material for use of this rapid test was either plasma or diluted pleural effusion. Twenty cats with moderate to severe pleural effusion were prospectively recruited. The cats were grouped into two groups, with or without congestive heart failure (CHF; N-CHF), after complete work-up. Blood and effusion were collected in EDTA tubes. Plasma and pleural effusion supernatants were transferred into stabilizer tubes and frozen. POC-ELISA for NT-proBNP was performed with plasma and diluted effusion (1:1). Quantitative NT-proBNP measurement was performed in plasma and diluted and undiluted effusions.

RESULTS

Six cats were assigned to the CHF group. Of the 14 cats in the N-CHF group, 6 had concurrent cardiac abnormalities that were not responsible for the effusion. For the detection of CHF, the test displayed respective sensitivities and specificities of 100% and 79% in plasma and 100% and 86% in diluted pleural fluid. Receiver operating characteristic (ROC) analysis for quantitative NT-proBNP measurement of plasma and diluted and undiluted pleural effusions displayed areas under the curve of 0.98, sensitivities of 100% and specificities of 86%. The optimum cut-off was calculated at 399 pmol/l in plasma and 229 pmol/l in the diluted effusion and 467 pmol/l in the undiluted effusion.

CONCLUSIONS

POC-ELISA for NT-proBNP in both plasma and diluted pleural effusion was suitable to differentiate cardiac from non-cardiac causes of feline pleural effusion. According to our results, use of pleural effusion is feasible, but dilution of the effusion before measurement seems to improve specificity.

N-terminal-pro brain natriuretic peptides in dogs and cats: A technical and clinical review

Biomarkers are quantitative indicators of biological processes performed by an organ or system. In recent years, natriuretic peptides (NPs) have emerged as important tools in the diagnosis and therapeutic monitoring of heart diseases. Research has shown that serum and plasma levels of N-terminal pro brain NP (NT-proBNP) in dogs and cats are the only biomarkers that afford to diagnose and monitor congestive processes and, indirectly, the myocardial function of small animals. The present review discusses the peer-reviewed specialized literature about NT-proBNP and presents and compares the potential clinical applications of this NP in veterinary medicine of small animals, considering diagnosis, follow-up, and prognosis of myocardial or systemic diseases. The relevance of NT-proBNP is associated with sample stability, easy determination in laboratory, sensitivity, accuracy, and the possibility to analyze myocardial function. These advantages are specially important when NT-proBNP is compared with other cardiac biomarkers, mostly those that indicate the integrity of the myocardial cell. Fast NT-proBNP assays are marketed today and may be used in association with complementary tests. Together, these methods are an important source of information in differential diagnosis of heart and lung diseases as well in the early diagnosis of cardiopathy in dogs and cats, proving valuable tools in treatment and prognosis.

Investigation of an N-Terminal Prohormone of Brain Natriuretic Peptide Point-of-Care ELISA in Clinically Normal Cats and Cats With Cardiac Disease

Background

N‐terminal prohormone of brain natriuretic peptide (NT‐proBNP) concentrations may be increased in cats with various cardiac disorders. The point‐of‐care (POC) ELISA assay uses the same biologic reagents as the quantitative NT‐proBNP ELISA. Previous studies have evaluated the sensitivity and specificity of the POC ELISA in cats with cardiac disease.

Objectives

To prospectively evaluate the diagnostic utility of the POC ELISA in a select population of cats.

Animals

Thirty‐eight client‐owned cats presented to the University of Florida Cardiology Service for cardiac evaluation. Fifteen apparently healthy cats recruited as part of another study.

Methods

Physical examination and echocardiography were performed in all cats. The POC ELISA was assessed visually as either positive or negative by a reader blinded to the echocardiographic findings, and results were analyzed relative to quantitative assay results.

Results

Twenty‐six cats were diagnosed with underlying cardiac disease, and 27 cats were considered free of cardiac disease. Cats with cardiac disease included: 21 with hypertrophic cardiomyopathy, 2 with unclassified cardiomyopathy, 2 with restrictive cardiomyopathy, and 1 with 3rd degree atrioventricular (AV) block. The POC ELISA differentiated cats with cardiac disease with a sensitivity of 65.4% and specificity of 100%.

Conclusions and Clinical Importance

The POC NT‐proBNP ELISA performed moderately well in a selected population of cats. A negative test result cannot exclude the presence of underlying cardiac disease, and a positive test result indicates that cardiac disease likely is present, but further diagnostic investigation would be indicated for a definitive diagnosis.

Association between Survival Time and Changes in NT-proBNP in Cats Treated for Congestive Heart Failure

Background

Reductions in N‐terminal pro‐B‐type natriuretic peptide (NT‐proBNP) concentrations after treatment have been associated with improved survival in people with congestive heart failure (CHF), but have not been reported in cats with CHF.

Objectives

To evaluate changes in NT‐proBNP concentrations in cats with CHF after treatment and determine whether serial NT‐proBNP measurements provide prognostic information.

Animals

Thirty‐one client‐owned cats.

Methods

Prospective, observational study in cats with new onset CHF secondary to cardiomyopathy. Concentrations of NT‐proBNP were measured within 4 hours of admission to the hospital, on the day of discharge, and at re‐evaluation 7–10 days later.

Results

Median NT‐proBNP concentrations decreased significantly from admission (1,713 pmol/L [range, 160–3,784 pmol/L]) to discharge (902 pmol/L [range, 147–3,223 pmol/L]); P = .005) and from admission to re‐evaluation (1,124 pmol/L [range, 111–2,727 pmol/L]; P = .024). Median survival time was 109 days (range, 1–709 days), with 5 cats still alive at the time of analysis. Cats with a larger percent decrease in NT‐proBNP from admission to discharge had a longer survival time (P = .048). Cats with evidence of active CHF at the time of re‐evaluation (P = .010) and cats whose owners had difficulty administering medications (P = .045) had shorter survival times.

Conclusions and clinical importance

Cats with a larger percent decrease in NT‐proBNP during hospitalization and no evidence of CHF at the time of re‐evaluation had longer survival times. Additional studies are needed to determine whether NT‐proBNP can help guide treatment in cats with CHF.

Screening for hypertrophic cardiomyopathy in cats

Hypertrophic cardiomyopathy (HCM) is the most common heart disease in cats, and it can lead to increased morbidity and mortality. Cats are often screened for HCM because of the presence of a heart murmur, but screening for breeding purposes has also become common. These cats are usually purebred cats of breeding age, and generally do not present with severe disease or with any clinical signs. This type of screening is particularly challenging because mild disease may be difficult to differentiate from a normal phenotype, and the margin for error is small, with potentially major consequences for the breeder. This article reviews HCM screening methods, with particular emphasis on echocardiography.

Cardiac biomarkers in cats

Cardiac biomarkers have been used in cats as part of the clinical assessment of heart disease for over a decade. They are widely available to practitioners through commercial reference laboratories. The evidence base for the use of cardiac biomarkers (primarily N-terminal pro-B type natriuretic peptide and cardiac troponin I) in cats is comprehensively reviewed in this article, focusing on each of six specific areas: distinguishing cardiac from non-cardiac causes of respiratory distress; measurement of cardiac biomarkers in urine and pleural fluid; identification of occult cardiomyopathy; effects of systemic disease on circulating concentrations of cardiac biomarkers; point-of-care biomarker testing, and the possible prognostic utility of cardiac biomarker measurement.

Point-of-care devices for physiological measurements in field conditions. A smorgasbord of instruments and validation procedures

Point-of-care (POC) devices provide quick diagnostic results that increase the efficiency of patient care. Many POC devices are currently available to measure metabolites, blood gases, hormones, disease biomarkers or pathogens in samples as diverse as blood, urine, feces or exhaled breath. This diversity is potentially very useful for the comparative physiologist in field studies if proper validation studies are carried out to justify the accuracy of the devices in non-human species under different conditions. Our review presents an account of physiological parameters that can be monitored with POC devices and surveys the literature for suitable quantitative and statistical procedures for comparing POC measurements with reference "gold standard" procedures. We provide a set of quantitative tools and report on different correlation coefficients (Lin's Concordance Correlation Coefficient or the more widespread Pearson correlation coefficient), describe the graphical assessment of variation using Bland-Altman plots and discuss the difference between Model I and Model II regression procedures. We also report on three validation datasets for lactate, glucose and hemoglobin measurements in birds using the newly proposed procedures. We conclude the review with a haphazard account of future developments in the field, emphasizing the interest in lab-on-a-chip devices to carry out more complex experimental measurements than the ones currently available in POC devices.

Differentiation of Cardiac from Noncardiac Pleural Effusions in Cats using Second-Generation Quantitative and Point-of-Care NT-proBNP Measurements

Background

Pleural effusion is a common cause of dyspnea in cats. N‐terminal pro‐B‐type natriuretic peptide (NT‐proBNP) measurement, using a first‐generation quantitative ELISA, in plasma and pleural fluid differentiates cardiac from noncardiac causes of pleural effusion.

Hypothesis/Objectives

To determine whether NT‐proBNP measurements using second‐generation quantitative ELISA and point‐of‐care (POC) tests in plasma and pleural fluid distinguish cardiac from noncardiac pleural effusions and how results compare to the first‐generation ELISA.

Animals

Thirty‐eight cats (US cohort) and 40 cats (UK cohort) presenting with cardiogenic or noncardiogenic pleural effusion.

Methods

Prospective cohort study. Twenty‐one and 17 cats in the US cohort, and 22 and 18 cats in the UK cohort were classified as having cardiac or noncardiac pleural effusion, respectively. NT‐proBNP concentrations in paired plasma and pleural fluid samples were measured using second‐generation ELISA and POC assays.

Results

The second‐generation ELISA differentiated cardiac from noncardiac pleural effusion with good diagnostic accuracy (plasma: sensitivity, 95.2%, specificity, 82.4%; pleural fluid: sensitivity, 100%, specificity, 76.5%). NT‐proBNP concentrations were greater in pleural fluid (719 pmol/L (134–1500)) than plasma (678 pmol/L (61–1500), P = 0.003), resulting in different cut‐off values depending on the sample type. The POC test had good sensitivity (95.2%) and specificity (87.5%) when using plasma samples. In pleural fluid samples, the POC test had good sensitivity (100%) but low specificity (64.7%). Diagnostic accuracy was similar between first‐ and second‐generation ELISA assays.

Conclusions and clinical importance

Measurement of NT‐proBNP using a quantitative ELISA in plasma and pleural fluid or POC test in plasma, but not pleural fluid, distinguishes cardiac from noncardiac causes of pleural effusion in cats.

Plasmonic-ELISA: expanding horizons

Convergence of localized surface plasmon resonance of metal nanoparticles with classical ELISA has emerged as a new class of immunoassays, i.e. plasmonic ELISA, enabling biocatalysis mediated ultrasensitive naked-eye detection of disease biomarkers.