Timely and sensitive detection of cardiac troponin I (cTnI) is critical for early diagnosis of myocardial infarction, particularly at the point-of-care. Herein, we present a novel colorimetric biosensing platform for high-sensitivity detection of cardiac troponin I (cTnI). The platform integrates magnetic particle (MP) anchored locked aptamers, stabilized by short complementary strands to minimize nonspecific folding and background activation prior to target binding, with hyperbranched hybridization chain reaction (HCR) and catalytic DNA (DNAzyme) nanocomplex-mediated signal amplification. This enzyme-free amplification system detects cTnI directly in 25-30 min, with a calculated detection limit of 0.25 ng L-1, a wide dynamic range of 0.5-50 000 ng L-1, and a coefficient of variation below 5% using just 25 µL of patient serum. The developed assay was evaluated using both human and canine serum samples. To assess classification performance, three distinct hyperparameter optimization strategies were applied to a reduced feature space. The model achieved an accuracy of 90.91% and a recall of 89.89% for human samples, and an accuracy of 83.33% with a recall of 85.71% for canine samples. Blind testing with human serum samples further confirmed the robustness of the platform, showing an overall accuracy of around 90%. This integrated biosensing and machine learning framework enables rapid and sensitive detection of cardiac troponin I, demonstrating strong potential for myocardial infarction diagnosis across species in a pre-clinical setting.

Cardiac troponin I (cTnI) is a cardiac specific biomarker of myocardial damage in humans, dogs, and cats. The ADVIA Centaur XP High-Sensitivity Troponin I assay (AC-cTnI-HS) has been validated for use in humans and dogs, but not for use in cats. The study objective was to analytically validate the AC-cTnI-HS assay for use in cats and to evaluate cTnI measurements in healthy cats compared to those with cardiac disease to assess the clinical utility of this assay. Surplus serum samples from cats were used for analytical validation. Intra- and inter-assay variability, dilutional parallelism, and spiking recovery were assessed. Serum samples from 106 client-owned cats were evaluated. This group was comprised of 51 clinically healthy cats (structurally normal echocardiogram, normal systemic blood pressure, and unremarkable complete blood count and biochemistry profile), 25 cats with stage B1 hypertrophic cardiomyopathy, 7 with stage B2 hypertrophic cardiomyopathy, 7 with stage C cardiomyopathy of any type, 8 with congenital heart disease, and 8 cats with transient myocardial thickening and/or suspected to have myocarditis. Inter-assay and intra-assay coefficients of variation were between 2.7-8.3% and 1.5-4.0%, respectively. The mean ± standard deviation observed to expected ratios for dilutional parallelism and spiking recovery were 124.3 ± 42.8% and 92.9 ± 6.2%, respectively. Healthy cats had significantly lower cTnI concentrations than cats with hypertrophic cardiomyopathy stage B1 (P = 0.012), stage B2 (P = 0.004), or any cardiomyopathy ACVIM stage C (P = 0.002). The AC-cTnI-HS assay is precise, reproducible, linear, and accurate for measurement of cTnI concentrations in serum from cats. This study confirms that measurement of serum cTnI holds promise to have clinical utility as it was able to detect differences in serum cTnI concentrations between healthy cats and those with cardiac disease.

Chagas disease, caused by the protozoan Trypanosoma cruzi, is a significant challenge for canine health, with limited diagnostic tools. This study assessed the performance of a novel Tc-24 recombinant antigen ELISA compared to three commercial diagnostic tests on 70 serum samples from kennel dogs in Texas. The Tc-24 ELISA demonstrated high sensitivity (87.5%) and specificity (91.2%) compared to Indirect Fluorescent Antibody (IFA) testing, with significant differences in Tc-24 optical density (OD) between positives and negatives (0.607 vs. 0.089, p < 0.001). When compared to Chagas Stat-Pak (SP), Tc-24 ELISA showed sensitivity and specificity values of 82.1% and 86.7%, respectively (p < 0.001). For Chagas Detect Plus (IB), the assay achieved a sensitivity of 80.0% and specificity of 93.1% (p < 0.001). Spearman correlation analysis revealed significant associations between Tc-24 OD and SP (r = 1.0, p = 0.0167), IB (r = 0.9, p = 0.0833) and IFA (r = 0.6273, p = 0.044). Elevated immunochromatographic values in commercial kits (SP or IB) correlated with Tc-24 OD (1.17 vs. 0.039, p < 0.001), achieving 100% sensitivity and 95.8% specificity based on positive results from commercial kits. These findings suggest that Tc-24 ELISA is a reliable and accurate serological tool for diagnosing T. cruzi infection in dogs, with the potential to enhance diagnostic capabilities in veterinary medicine.

Trypanosoma cruzi (Chagas, 1909) is a protozoan parasite transmitted by triatomine (Hemiptera: Reduviidae) insects and is the causative agent of Chagas disease. Oral transmission of the parasite occurs through consumption of contaminated food or infected triatomines and may depend on the degree to which T. cruzi survives in triatomine abdomens. Dead triatomines may be abundant in areas with insecticide use, such as dog kennels where animals may encounter them. We attempted to culture T. cruzi from the gut material of 108 triatomines collected near dog kennels-14 found alive and 94 found dead-and also tested for T. cruzi DNA and discrete typing units using PCR. In total, 30 (27.8%) tested positive for T. cruzi using PCR, 5 alive (35.7%) and 25 dead (26.6%), with no difference in infection between insects found alive versus dead (P-value = 0.53) and more PCR positives identified in dead triatomines with intact gut contents than in dead desiccated triatomines (P-value = 0.049). One Paratriatoma lecticularia (Stål, 1859) that was found dead (1.1%, n = 94) had T. cruzi growth in culture. Given the use of bleach for external decontamination of triatomines as well as the level of bacterial and fungal contamination of cultures, both of which may have impacted the growth of T. cruzi, the apparent prevalence of viable parasites in this study should be interpreted as a conservative estimate. Vector control initiatives should consider that dead insects may still pose a risk of T. cruzi transmission to animals and humans.

INTRODUCTION/OBJECTIVES:Standard poodle (SP)/Standard poodle crossbred (SP-C) dogs have gained popularity with limited literature representation. The study objective was to report clinical, imaging, and procedural data in SP/SP-C dogs with patent ductus arteriosus (PDA). ANIMALS:Breeds included SP (12/30), Goldendoodle (9/30), Labradoodle (7/30), and Bernedoodle (2/30). At presentation, dogs were 0.6 years old (0.2-6.0) and weighed 14.8 kg (3.1-25.6). Nine had concurrent congenital heart disease. Thirteen required diuretic therapy. MATERIALS AND METHODS: A multi-institutional retrospective study including 30 client-owned SP/SP-C dogs was conducted. Data are reported as median and range. RESULTS:Intra-operative imaging was performed with angiography (n = 28) and transesophageal echocardiography (TEE) (n = 20), with discrepancies in morphology classification identified in six dogs in which both modalities were performed. Pulmonary ostium diameter measured by TEE, ampulla diameter 4 mm above the ostium measured by TEE (TEE-Amp4), ampulla diameter at the level of the aorta measured by TEE, and ampulla length were measured. Pulmonary ostium diameter measured by TEE was 4.1 mm (1.4-8.1), measuring 42% (35-66%) of the TEE-Amp4. Closure methods included the use of an Amplatz canine duct occluder (ACDO) device (27/30) and surgical ligation (3/30). The median ACDO size was 7 mm (3-12). Immediately after ACDO occlusion, TEE-Amp4 and ampulla diameter at the level of the aorta measured by TEE had a median increase of 21% (0-148) and 16% (4-59), respectively. Complications occurred in four dogs (intra-operative atrial fibrillation [2/30], device embolization following ampulla dilation with subsequent ligation [1/30], and postoperative death following PDA rupture with partial ligation [1/30]). STUDY LIMITATIONS:Potential errors in breed identification and imaging could affect results. CONCLUSIONS:Standard poodle and crossbred dogs can have large or unusually shaped PDAs, with TEE imaging able to provide anatomic information and intra-operative monitoring.

Infection with the protozoan parasite Trypanosoma cruzi is generally well-controlled by host immune responses, but appears to be rarely eliminated. The resulting persistent, low-level infection results in cumulative tissue damage with the greatest impact generally in the heart in the form of chagasic cardiomyopathy. The relative success in immune control of T. cruzi infection usually averts acute phase death but has the negative consequence that the low-level presence of T. cruzi in hosts is challenging to detect unequivocally. Thus, it is difficult to identify those who are actively infected and, as well, problematic to gauge the impact of treatment, particularly in the evaluation of the relative efficacy of new drugs. In this study, we employ DNA fragmentation and high numbers of replicate PCR reaction (‘deep-sampling’) and to extend the quantitative range of detecting T. cruzi in blood by at least three orders of magnitude relative to current protocols. When combined with sampling blood at multiple time points, deep sampling of fragmented DNA allowed for detection of T. cruzi in all infected hosts in multiple host species, including humans, macaques, and dogs. In addition, we provide evidence for a number of characteristics not previously rigorously quantified in the population of hosts with naturally acquired T. cruzi infection, including, a >6 log variation between chronically infected individuals in the stable parasite levels, a continuing decline in parasite load during the second and third years of infection in some hosts, and the potential for parasite load to change dramatically when health conditions change. Although requiring strict adherence to contamination–prevention protocols and significant resources, deep-sampling PCR provides an important new tool for assessing therapies and for addressing long-standing questions in T. cruzi infection and Chagas disease.

Companion dogs are a powerful model for aging research given their morphologic and genetic variability, risk for age-related disease, and habitation of the human environment. In addition, the shorter life expectancy of dogs compared to human beings provides a unique opportunity for an accelerated timeline to test interventions that might extend healthy lifespan. The Test of Rapamycin In Aging Dogs (TRIAD) randomized clinical trial is a parallel-group, double-masked, randomized, placebo-controlled, multicenter trial that will test the ability of rapamycin to prolong lifespan and improve several healthspan metrics in healthy, middle-aged dogs recruited from Dog Aging Project participants. Here, we describe the rationale, design, and goals of the TRIAD randomized clinical trial, the first rigorous test of a pharmacologic intervention against biological aging with lifespan and healthspan metrics as endpoints to be performed outside of the laboratory in any species.

PRACTICAL RELEVANCE:Cardiomyopathies are a common condition and the leading cause of congestive heart failure (CHF) in cats; however, to date there have been limited therapeutic options available. Commonly used therapeutics include diuretics for CHF and antithrombotics 2 to reduce the risk of arterial thromboembolism (ATE), which do not directly affect myocardial function. This review summarizes the evidence for the use of pimobendan, a phosphodiesterase III inhibitor and calcium channel sensitizer, in feline cardiomyopathies. Potential benefits of pimobendan in cats include improved left ventricular systolic and diastolic function, reduced platelet aggregation, reduction in left atrial size, and improved left atrial and auricular systolic function.Drug details:Pimobendan is indicated for the treatment of CHF in conditions associated with systolic dysfunction (including dilated cardiomyopathy, restrictive cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy and some cases with non-specific phenotypes) and has been used in the treatment of CHF secondary to hypertrophic cardiomyopathy. A dosage of pimobendan of 0.25 mg/kg PO q12h is generally well tolerated, and an approved oral solution is now available in the UK, EU, USA, Japan and Australia, which may facilitate administration in some cats; it should be noted, however, that pimobendan is not licensed for use in cats and marketing authorizations may vary between countries. Adverse events are uncommon with pimobendan but include gastrointestinal upset (anorexia, vomiting), transient changes in heart rate and possible worsening arrhythmias at higher doses. The use of pimobendan is contraindicated in cats with fixed obstructions of the left or right ventricular outflow tract (ie, congenital heart disease - pulmonic or aortic valvular stenosis). AUDIENCE:This article reviews the use of pimobendan in cats for primary care veterinarians and includes practical case examples that reflect the typical use and recommendations for usage of pimobendan by the authors.

Objective:To describe cardiovascular intra-anesthetic complications and ultrasensitive serum cardiac troponin I (cTnI) concentrations in dogs anesthetized repeatedly for radiation therapy (RT). Animals:12 client-owned dogs anesthetized once daily (Monday through Friday) for 10 to 20 sessions, totaling 218 general anesthesia (GA) episodes. Clinical Presentation:American Society of Anesthesiologists III sevoflurane-anesthetized dogs (median age, 10 years [range, 2 to 11]; body weight, 27.5 kg [range, 6.0 to 42.3]) undergoing RT. Results:Comparing the first 5 to the last 5 GA episodes, the incidence of bradycardia (heart rate [HR] < 60 beats/min) decreased from 58.3% to 43.8%, hypotension (mean arterial pressure [MAP] < 60 mm Hg) from 28.3% to 16.3%, and hypertension (MAP > 120 mm Hg) from 20.0% to 9.4%. Tachycardia (HR > 160 beats/min [10%]) and ventricular arrhythmias (2.3%) remained infrequent. Fluid bolus administration increased from 5.0% to 20.8%; anticholinergics and inotropes decreased from 35.0% to 15.0%. Median (range) cTnI concentrations were (ng/mL) 0.073 (0.007 to 0.685) at baseline and 0.083 (0.006 to 0.685), 0.073 (0.018 to 0.286), 0.062 (0.010 to 0.265), and 0.033 (0.026 to 0.121) after 5, 10, 15, and 20 GA episodes, respectively. Two dogs had transient elevations after 5 GA episodes (0.132 and 0.500 ng/mL), which normalized; 3 had elevated baseline cTnI (0.135 to 0.685 ng/mL), which decreased during RT; 1 had cardiac disease. Clinical Relevance:With cardiovascular monitoring and timely support, intra-anesthetic complication decreased, and cTnI remained stable or declined with repeated anesthetics. These findings support owner-informed decision-making regarding repeated GA for RT in dogs.

OBJECTIVE To describe associations between cardiac abnormalities and Trypanosoma cruzi serostatus by use of a simplified diagnos- tic evaluation in dogs at risk for T cruzi infection. METHODS A prospective, cross-sectional study was performed using a simplified diagnostic evaluation including high-sensitivity cardiac troponin I, 30-second ECG, and echocardiogram with 7 variables in 46 client-owned dogs from high-risk environ- ments. Dogs were categorized as serologically positive (SP), negative (SN), or discordant (SD) by use of 2 antibody tests. Functional evaluation of cardiac health scores and blood PCR were obtained. RESULTS Dogs were SP (n = 19), SN (17), and SD (10), with 9 PCR positive (7 SP, 1 SN, 1 SD). Troponin was above reference range in 6 of 46 (4 SP, 1 SN, 1 SD), and functional evaluation of cardiac health scores were 0 in all dogs. Conduction system ab- normalities (prolonged interval durations, second-degree atrioventricular block, splintered QRS complex) and ventricular arrhythmias were documented in 8 (7 SP, 0 SN, 1 SD). Twenty-six (12 SP, 8 SN, 6 SD) had echocardiographic abnormalities, most often myxomatous mitral valve disease (MMVD) and left ventricular enlargement. Seropositive dogs were significantly older and had a higher likelihood of MMVD. Conduction system abnormalities were associated with positive serostatus. CONCLUSIONS Echocardiographic abnormalities were complicated by MMVD and did not distinguish between serostatus. An ECG with assessment and detailed measurement of complexes and cardiac troponin I are simple tests to perform with abnormali- ties detected in seroreactive dogs. CLINICAL RELEVANCE Electrocardiographic abnormalities in high-risk or seroreactive dogs should prompt further evaluation and monitoring of Tcruzi infection.

The unique imaging capabilities of transesophageal echocardiography (TEE) make it a valuable tool for characterizing the structure and function of the heart and for providing procedural monitoring. With the creation of new devices and expansion of procedural options with increased applications, multiplanar and three-dimensional imaging with TEE can be essential for clinical decision making. A description of the indications and clinical application of TEE in animals while highlighting probe characteristics, limitations and patient safety are the focus of this review. The increased availability of three-dimensional imaging in smaller probes, advanced applications including photorealistic and fusion imaging, and the development of recommended standards for performing a comprehensive TEE imaging study including training guidelines may facilitate the use of TEE in the veterinary field.

Trypanosoma cruzi , the protozoan parasite and cause of Chagas disease, is widely distributed in many vertebrate and triatomine species throughout North, Central, and South America. Variations in housing quality largely determines human infection risk in the Americas. However, the southern U.S. contains widespread, infected triatomine vectors and captive species and domesticated animals with active T. cruzi infection or at high risk of becoming infected and developing Chagas disease. There is a critical need for better detection and intervention strategies, principally focused on human infection throughout the Americas, but mainly in the U.S., for high-value dogs employed in government and other work. In addition to this economic impact, the concentration of largely unavoidable T. cruzi infections in U.S. dogs provides an incomparable opportunity to answer questions related to T. cruzi infection and Chagas disease that are impossible or unethical to address in humans. As the course of T. cruzi infection and Chagas disease, the immune response to infection, and the response to therapeutics are highly similar across the range of mammalian host species, information obtained from studies in other species can directly inform researchers on how to best detect, manage, and treat T. cruzi infection and Chagas disease in humans.

Double outlet right atrium (DORA) is a type of atrioventricular septal defect (AVSD) that has been rarely reported in the domestic cat (Felis catus).1-3 One prevalence study of congenital heart disease in cats reported 6 AVSDs out of the 57,418 cats whose records were evaluated, none of which had DORA morphology.1 Another study describing the natural history of AVSDs in 26 cats reported that only 4 of the cases had DORA morphology.2 Clinical presentation is variable, with clinical signs ranging from vomiting and hyporexia to respiratory distress.

The prevalence of anatomical-based subtypes of feline congenital extrahepatic portosystemic shunts (EHPSS) has not been completely elucidated. The goal of this study was to use CT angiography to create an anatomical-based nomenclature system for feline congenital EHPSS. Additionally, subjective portal perfusion scores were generated to determine if intrinsic portal vein development was associated with different shunt conformations or patient age at the time of CT. The SVSTS and VIRIES list services were used to recruit cases. Data collected included patient DOB, gender, breed, weight, CT date, and reported diagnosis. Shunts were classified based upon (1) the shunt portal vessel(s) of origin, (2) the shunt systemic vessel(s) of insertion, and (3) any substantial portal vessels contributing to the shunt. Additionally, hepatic portal perfusion was subjectively scored between 1 (poor/none) and 5 (good/normal) based on the caliber of the intrahepatic PVs. A total of 264 CT scans were submitted from 29 institutions. Due to exclusion criteria, 33 (13%) were removed, leaving 231 CT scans to be included. Twenty-five different EHPSS anatomies were identified with five classifications accounting for 78% of all shunts (LGP [53%], LGC-post [11%], LCG [7%], LGC-pre [4%], and PC [4%]). Shunt origin involved the left gastric vein in 75% of the described classifications. Significant differences were identified among the five most common shunt types with respect to age at the time of CT scan (P = .002), breed (P < .001), and subjective portal perfusion score (P < .001). This refined anatomical classification system for feline EHPSS may enable improved understanding, treatment comparisons, and outcome prediction for cats with these anomalies.

Abstract Trypanosoma cruzi infection in dogs can cause heart failure and sudden death with few treatment options available. A litter of 4 dogs living in a T cruzi endemic area were randomized to prophylaxis and nonprophylaxis groups as part of a study evaluating a modified benznidazole dosing regimen administered twice weekly to prevent T cruzi infection during a vector transmission season. The 2 dogs that received prophylaxis remained healthy without T cruzi infection or cardiac disease for >2 years. One dog that did not receive prophylaxis died unexpectedly with acute T cruzi–induced pancarditis, and the second dog tested positive for T cruzi and developed complex arrhythmias with markedly increased cardiac troponin I and improved with a higher benznidazole treatment dose. Although the small sample size precludes definitive conclusions, we describe the potential clinical benefit of prophylactic and early treatment with modified benznidazole dosing regimens for dogs with T cruzi infection.

Differentiation of more complicated forms of tetralogy of Fallot (TOF), including pulmonary atresia with ventricular septal defect (VSD), from truncus arteriosus and other complex congenital malformations can be challenging with transthoracic echocardiography (TTE) alone, and though there are identifiable characteristics that can help make the differentiation, advanced imaging is typically required to provide a full picture of the anatomy and identify the sources of pulmonary blood flow. These defects have rarely been reported in the dog, cat, alpaca, and cow.

OBJECTIVE:To develop breed-specific echocardiographic values for normal Borzoi and to report the prevalence of structural cardiac abnormalities.ANIMALS:146 clinically healthy, adult Borzoi dogs.METHODS:Cardiac auscultation and standard echocardiograms were performed. Longitudinal follow-up was described in a subset of dogs (n = 25).RESULTS:Most Borzoi were structurally normal (119/146, 81.5%), with breed-specific echocardiographic values generated independently for each sex, as females weighed significantly less than males (30.4 ± 3.8 kg vs 38.3 ± 4.1 kg, respectively; P < .001), and a significant impact of sex was found on most measurements. Physiologic heart murmurs were identified in 64/119 (53.8%) normal dogs. Thirty-six (30.2%) structurally normal dogs had trace or mild mitral regurgitation, and 43 (36.1%) had trace or mild tricuspid regurgitation. Structural cardiac disease was identified in 21 dogs (14.4%), including 9 dogs (6.2%) with dilated cardiomyopathy (DCM), 9 dogs (6.2%) with stage B1 myxomatous mitral valve disease (MMVD), and 3 (2.1%) dogs with congenital abnormalities. Seven dogs (4.8%) had equivocal abnormalities. During follow-up, new dogs were diagnosed with occult DCM (n = 3), equivocal DCM (1), and stage B1 MMVD (2). Two dogs originally diagnosed with DCM (1 occult and 1 equivocal) normalized after diet change.CLINICAL RELEVANCE:Borzoi dogs commonly have physiologic heart murmurs and mild atrioventricular valve regurgitation. Both DCM and MMVD were identified at similar frequencies in healthy Borzoi, although dogs with MMVD all had normal heart sizes. Echocardiographic screening for DCM in Borzoi should be considered, with breed-specific echocardiographic values now available for improved diagnostic confidence.

OBJECTIVE Borzoi reportedly experience sudden death. The objective of this study was to report ECG intervals, amplitudes, and frequency of ECG abnormalities in clinically healthy Borzoi. METHODS 98 clinically healthy Borzoi were prospectively recruited and underwent echocardiogram, ECG, and cardiac troponin I testing between October 2020 and December 2022. Standard ECG measurements were obtained. Early repolarization notches and slurs were recorded. RESULTS Of 82 Borzoi with a structurally normal echocardiogram, ventricular arrhythmias were documented in 8 (10%) dogs, all of which had normal cardiac troponin I concentrations. Median P wave duration was 55 milliseconds (range, 45 to 70 milliseconds). Median PR interval was 125 milliseconds (range, 80 to 175 milliseconds). Thirty-one (38%) Borzoi had first-degree atrioventricular block (PR interval > 130 milliseconds). Median QRS duration was 65 milliseconds (range, 48 to 90 milliseconds). Median QT interval was 235 milliseconds (range, 185 to 275 milliseconds). Twenty-nine (35%) and 15 (18%) of 82 Borzoi had QT intervals > 240 or > 250 milliseconds, respectively. Sixty-seven of 82 (82%) Borzoi had early repolarization notches or slurs. Seventeen of 82 (21%) Borzoi had an abnormality of the ST segment, most commonly convexity/doming. Convexity of the ST segment was intermittent (n = 9) or persistent (4). CONCLUSIONS Ventricular arrhythmias, early repolarization, prolonged QT intervals, and ST segment abnormalities are not infrequent in clinically healthy Borzoi. P, PR, and QRS durations are commonly prolonged compared to general canine reference intervals. CLINICAL RELEVANCE Future study into heritable channelopathies in Borzoi is warranted given the frequency of ventricular arrhythmias, repolarization abnormalities, and sudden death in the breed. Breed-specific ECG reference intervals are needed.