Evaluation of the use of a heparin dose-response test in dogs to determine the optimal heparin dose during intravascular procedures and assessment of the in vitro heparin response in healthy dogs

BACKGROUND

No guidelines for administering and monitoring anticoagulants intraprocedurally are currently available in dogs, despite the prevalence of procedures necessitating systemic anticoagulation with heparin.

OBJECTIVES

To evaluate an activated clotting time (ACT)-based heparin dose-response (HDR) test to predict the individual required heparin dose in dogs during intravascular procedures, and to investigate both the in vitro heparin - ACT and in vitro heparin - factor anti-Xa activity (anti-Xa) relationships in dogs.

METHODS

Blood was collected from eight healthy beagles undergoing a cardiac procedure and utilised to establish baseline ACT and for in vitro evaluation. Subsequently, 100 IU/kg heparin was administered intravenously (IV) and ACT was remeasured (HDR test). The required heparin dose for an ACT target response ≥300 s was calculated for each individual and ACT was remeasured after administration of this dose. For in vitro testing, a serial heparin blood dilution (0-0.5-1-2-4 international unit (IU)/mL) was prepared and ACT and anti-Xa were determined using whole blood and frozen plasma, respectively.

RESULTS

The HDR test overestimated the required heparin dose in 3/7 dogs. In vitro, ACT and anti-Xa increased significantly with increasing blood heparin concentration. Heparin - ACT was nonlinear in 4/8 dogs at heparin concentrations >2 IU/mL, whereas heparin - anti-Xa remained linear throughout the tested range.

CONCLUSIONS

The HDR test poorly estimated the required heparin dose in dogs. This is most likely attributed to a nonlinear heparin - ACT relationship, as observed in vitro. Anti-Xa is a promising alternative for ACT; however, unavailability as a point-of-care test and lack of in vivo target values restrict its current use.

Classification of feline hypertrophic cardiomyopathy-associated gene variants according to the American College of Medical Genetics and Genomics guidelines

Introduction

The correct labeling of a genetic variant as pathogenic is important as breeding decisions based on incorrect DNA tests can lead to the unwarranted exclusion of animals, potentially compromising the long-term health of a population. In human medicine, the American college of Medical Genetics (ACMG) guidelines provide a framework for variant classification. This study aims to apply these guidelines to six genetic variants associated with hypertrophic cardiomyopathy (HCM) in certain cat breeds and to propose a modified criterion for variant classification.

Methods

Genetic samples were sourced from five cat breeds: Maine Coon, Sphynx, Ragdoll, Devon Rex, and British Short- and Longhair. Allele frequencies were determined, and in the subset with phenotypes available, odds ratios to determine the association with HCM were calculated. In silico evaluation followed with joint evidence and data from other publications assisting in the classification of each variant.

Results

Two variants, MYBPC3:c.91G > C [A31P] and MYBPC3:c.2453C > T [R818W], were designated as pathogenic. One variant, MYH7:c.5647G > A [E1883K], was found likely pathogenic, while the remaining three were labeled as variants of unknown significance.

Discussion

Routine genetic testing is advised solely for the MYBPC3:c.91G > C [A31P] in the Maine Coon and MYBPC3:c.2453C > T [R818W] in the Ragdoll breed. The human ACMG guidelines serve as a suitable foundational tool to ascertain which variants to include; however, refining them for application in veterinary medicine might be beneficial.

Successful high-resolution three-dimensional electroanatomical mapping and radiofrequency catheter ablation of a posteroseptal accessory pathway in a dog using CARTO 3

A one-year-and-seven-month-old, 28 kg, male castrated crossbreed dog was presented for supraventricular tachycardia causing recurrent episodes of anorexia and lethargy. Sotalol (2.2 mg/kg q12 h) reduced the frequency of symptomatic episodes but did not provide full relief. Three-dimensional electroanatomical mapping was performed at the Ghent University Small Animal Teaching hospital using the CARTO 3. Right atrial activation mapping identified the earliest atrial activation right posteroseptal, near the tricuspid annulus. Fast retrograde ventriculoatrial conduction during tachycardia and extrastimulus testing confirmed the presence of a concealed right posteroseptal accessory pathway. Six radiofrequency catheter ablation applications were delivered, and tachycardia remained uninducible. The dog recovered well from the procedure. Sotalol was stopped three weeks later, and no more clinical signs were noted by the owner. Repeated 24-hour electrocardiography monitoring on day one and at 1, 3, and 12 months after the procedure showed no recurrence of tachycardia.

Pulmonary arteriovenous malformation and a concurrent patent ductus arteriosus in a Doberman

A 7-week-old male Doberman presented with tachypnea, dyspnea and a VI/VI, left cranial, continuous heart murmur. Thoracic radiographs revealed severe left-sided cardiomegaly, presence of a rounded soft tissue opacity in the caudodorsal aspect of the thoracic cavity and signs of left-sided congestive heart failure. Clinical signs of heart failure were medically controlled. Echocardiography and computed tomography demonstrated a left-to-right shunting patent ductus arteriosus (PDA) in combination with a right-to-left shunting pulmonary arteriovenous malformation (PAVM) between the right main pulmonary artery and the right caudal pulmonary vein. Arterial blood gasses revealed mild hypoxemia. Transcatheter occlusion of the PDA using an Amplatz Canine Duct Occluder was performed. Four months post-operatively, echocardiography showed normal cardiac size and function with complete PDA closure. Thoracic radiographs revealed absence of the rounded opacity and resolution of cardiomegaly and vascular congestion. The PAVM was no longer visualized on repeated computed tomography and the arterial blood gasses were within normal limits. A PAVM connecting a pulmonary artery to a pulmonary vein has only rarely been reported in dogs. This report describes the presence of a congenital PAVM in combination with a PDA in a dog, which has not been previously reported in veterinary medicine.

Surgical correction of an infundibular pulmonic stenosis and ventricular septal defect in a Shetland Sheepdog

A four-month-old male Shetland Sheepdog presented with exercise intolerance. Physical examination revealed an IV/VI left cranial systolic heart murmur. Echocardiography showed a severe infundibular pulmonic stenosis and a concomitant restrictive ventricular septal defect. As clinical signs of congestive right-sided heart failure worsened and were refractory to medical treatment, surgical correction was advised. Via sternotomy, with cardiopulmonary bypass and cardioplegic cardiac arrest, ventricular septal defect closure and resection of the stenotic infundibular band were performed through right ventriculotomy, followed by patch enlargement. Postoperative recovery was uneventful and echocardiography showed complete resolution of the stenosis and successful closure of the ventricular septal defect. Follow-up echocardiography revealed restenosis after seven weeks and recurrence of right-sided heart failure three months postoperatively. Stenting of the restenosis was attempted via a hybrid procedure with sternotomy and direct transventricular approach. The dog developed fatal ventricular fibrillation during stent deployment. This is the first dog in which surgical right ventricular patch enlargement under cardiopulmonary bypass is reported for the treatment of a primary infundibular pulmonic stenosis.

Three-dimensional electroanatomical mapping for guidance of pulmonary vein isolation as treatment for persistent atrial fibrillation in a dog

A two-year and four-month, male German Shepherd was referred for exercise intolerance and panting. Irregular heart auscultation (250 beats per minute (bpm)) and pulse deficits were noted on physical exam. Electrocardiogram (ECG) showed irregular, narrow-QRS tachycardia without P waves compatible with coarse atrial fibrillation (AF). A 24-h ECG showed sustained AF (mean ventricular response rate 92 bpm). Echocardiography showed no structural abnormalities. Given the young age and presence of AF-related symptoms, rhythm control was preferred. Transthoracic electrical cardioversion was successfully performed six weeks later but AF recurred within 24-h. Sotalol was started but discontinued due to poor tolerance and AF persisted. Seven months after AF diagnosis, radiofrequency catheter ablation (RFCA) aiming for pulmonary vein isolation was performed under general anaesthesia. After transseptal puncture, three-dimensional electroanatomical mapping of the left atrium was performed. Point-by-point pulmonary vein isolation was achieved by RFCA. Seventy-eight RFCA lesions were placed in the left atrium encircling the three pulmonary vein ostia followed by electrical cardioversion. No complications occurred and the dog was discharged with amiodarone. In the immediate post-operative phase, there was recurrence of persistent AF requiring electrical cardioversion. Furthermore, at one month after the ablation, the dog experienced a single and transient paroxysm of AF. Since then, stable sinus rhythm (SR) was retained on daily ECG monitoring at home and confirmed by 24-h ECG three months post-operatively. Amiodarone was stopped subsequently. At the time of writing (one year post-operative), the dog remains in SR with normal exercise tolerance.

Systolic blood pressure measurements with Doppler ultrasonic flow detector and high-definition oscillometry are comparable on population level but show large intra-individual differences in apparently healthy elderly dogs

OBJECTIVE

Agreement of systolic blood pressure measurements (SBP) between noninvasive blood pressure devices in conscious dogs is poorly studied. Situational hypertension is expected in clinics, but studies are lacking. This study aimed to compare SBP measurements obtained with Doppler ultrasonic flow detector (Doppler) versus high-definition oscillometry (HDO) in clinics and at home and to estimate the prevalence of situational hypertension in conscious, apparently healthy elderly dogs.

ANIMALS

122 apparently healthy elderly or geriatric dogs were prospectively recruited.

PROCEDURES

Systolic blood pressure was obtained consecutively with Doppler and HDO techniques in a randomized order per dog, following a standardized protocol. An at-home measurement was advised for in-clinic hypertensive dogs (SBP ≥ 160 mmHg), also using both devices.

RESULTS

Dual measurements were available in 102 dogs. Median SBP was 147.3 mmHg (range, 105 to 239 mmHg) for Doppler and 152.3 mmHg (range, 113 to 221 mmHg) for HDO. Forty-six percent (56/122) were hypertensive, of which 9% (11/122) were hypertensive with both methods. No significant difference was found between the 2 devices in the global study population or within the group of hypertensive dogs. Repeated at-home measurements were performed in 20/56 (35.7%) hypertensive dogs, resulting in a 10 and 26 mmHg lower median SBP value for Doppler and HDO, respectively (P > .05). In-clinic situational hypertension was presumed in 8/20 (40%) dogs.

CLINICAL RELEVANCE

The choice of the noninvasive blood pressure device did not significantly impact SBP results, but large interindividual differences in SBP between techniques occurred. Situational hypertension was frequently observed in clinic.

Reference interval, longitudinal variability and reliability of activated clotting time in healthy dogs using a point-of-care analyser

BACKGROUND

Activated clotting times (ACTs) are used to screen for coagulopathies and monitor heparin therapy.

OBJECTIVES

To determine a reference interval (RI) for ACT in dogs using a point-of-care analyser, to quantify intra-subject within- and between-day variability, to quantify analyser reliability and inter-analyser agreement and to study the influence of a delay in measurement.

METHODS

Forty-two healthy dogs were included. Measurements were performed on fresh venous blood using the i-STAT 1 analyser. The RI was determined using the Robust method. Intra-subject within-day variability and between-day variability were quantified between baseline and 2 h (n = 8) or 48 h (n = 10) later. Analyser reliability and inter-analyser agreement were studied by duplicate measurements (n = 8) on identical analysers. The influence of measurement delay was studied before and after a delay of one analytical run (n = 6).

RESULTS

Mean, lower and upper reference limits for ACT were 92.9 ± 9.1, 74.4 and 111.2 s, respectively. Coefficients of variation of intra-subject within- and between-day variability were 8.1% and 10.4%, respectively, resulting in a significant between-day measurement difference. Analyser reliability assessed by the intraclass correlation coefficient and coefficient of variation were 0.87% and 3.3%, respectively. Significantly lower ACT values were observed after a measurement delay compared to direct analysis.

CONCLUSIONS

Our study provides an RI for ACT in healthy dogs using the i-STAT 1 and suggests low intra-subject within- and between-day variability. Analyser reliability and inter-analyser agreement were good; however, analysis delay and between-day differences could significantly influence ACT results.

Assessment of Cardiotoxicity after a Single Dose of Combretastatin A4-Phosphate in Dogs Using Two-Dimensional Speckle-Tracking Echocardiography

Simple Summary

Combretastatin A4-phosphate is a chemotherapeutic drug which has been evaluated for treatment of solid canine tumors. Previous studies reported cardiotoxic effects based on changes in cardiac troponin I measurements, blood pressure, and electrocardiography. We evaluated the cardiotoxic effect by two-dimensional speckle tracking echocardiography. This advanced imaging technique analyzes global and regional myocardial function and is used as the gold-standard for the assessment of cardiac function in human patients receiving chemotherapy. We found that certain strain measurements were significantly decreased 24 h after the administration of combretastatin A4-phosphate and that these changes were correlated with an increase in cardiac troponin I. Our results suggest that two-dimensional speckle tracking may be useful for the early detection of cardiac dysfunction in canine cancer patients as well as promising during follow-up.

Abstract

Combretastatin A4-phosphate (CA4P) is a vascular disrupting agent that was recently described for the treatment of solid canine tumors. Conventional echocardiography and pulsed wave tissue Doppler imaging did not reveal cardiotoxicity in dogs, however, the gold standard for assessing myocardial damage in humans receiving cardiotoxic chemotherapeutics is two-dimensional speckle-tracking echocardiography. The current study evaluated the cardiotoxic effect of a single dose of CA4P in dogs using peak systolic strain measurements and the variability of these measurements. Echocardiographic examinations of seven healthy beagles and five canine cancer patients that received CA4P were retrospectively reviewed. Peak systolic regional longitudinal strain (LSt), peak systolic regional circumferential strain (CSt), and peak systolic regional radial strain (RSt) were measured before and 24 h after administration of CA4P. Peak systolic strain measurements were compared to serum cardiac troponin I (cTnI). To quantify intra- and inter-observer measurement variability, seven echocardiographic examinations were selected and each strain parameter was measured by three observers on three consecutive days. After CA4P administration, the median LSt and CSt values decreased by 21.8% (p = 0.0005) and 12.3% (p = 0.002), respectively, whereas the median RSt values were not significantly different (p = 0.70). The decrease in LSt was correlated with increased serum cTnI values (Spearman rho = −0.64, p = 0.02). The intra-observer coefficients of variation (CV) were 9%, 4%, and 13% for LSt, CSt, and RSt, respectively, while the corresponding interobserver CVs were 11%, 12%, and 20%. Our results suggest that regional peak systolic strain measurements may be useful for the early detection of cardiotoxicity that is caused by vascular disrupting agents and that LSt may be promising for the follow-up of canine cancer patients.

Pharmacokinetic and pharmacodynamic properties of orally administered torasemide in healthy cats

BACKGROUND

In people and dogs, torasemide has higher bioavailability, longer half-life, and longer duration of action than equivalent doses of furosemide but data regarding pharmacological properties of torasemide in cats are limited.

OBJECTIVE

To assess pharmacokinetic and pharmacodynamic parameters of torasemide in healthy cats, and to investigate the effects of a single administration of torasemide on indicators of diuresis, plasma creatinine concentration, blood pressure, electrolyte concentrations and markers of the renin-angiotensin-aldosterone system (RAAS).

ANIMALS

Six clinically healthy adult European shorthair cats.

METHODS

Randomized 4-period crossover design with 3 groups and 4 treatments. Pharmacokinetic parameters were obtained using a noncompartmental analysis, and the clinically effective dose was assessed using a Hill model.

RESULTS

Mean absolute bioavailability was estimated at 88.1%. Mean total body clearance was 3.64 mL/h/kg and mean terminal half-life was 12.9 hours. Urine output significantly increased after torasemide administration (P < .001). The urine sodium : potassium ratio (uNa : uK) paralleled and was statistically correlated to urine output (P < .001). Administration of a single torasemide dose led to a significant dose-dependent increase in urine aldosterone : creatinine ratio (uAldo : C; P < .001) and a transient decrease in plasma potassium concentration (P < .001) but did not affect blood pressure or plasma creatinine concentration.

CONCLUSIONS AND CLINICAL IMPORTANCE

A single torasemide dose leads to a significant increase in diuresis and renin-angiotensin-aldosterone system (RAAS) activation in healthy cats, with high absolute bioavailability, and without clinically relevant adverse effects. Pharmacokinetic parameters indicate that once daily dosing of 0.27 mg/kg may be appropriate in a clinical setting.

The TNNT2:c.95-108G>A variant is common in Maine Coons and shows no association with hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a common and potentially fatal heart disease in many cat breeds. An intronic variant in TNNT2, c.95-108G>A, was recently reported as the cause of HCM in the Maine Coon. The aim of this study was to determine this variant's allele frequency in different populations and its possible association with HCM. Based on 160 Maine Coon samples collected in Belgium, Italy, Sweden and the USA, the variant's allele frequency was estimated to be 0.32. Analysis of the 99 Lives feline whole genome sequencing database showed that the TNNT2 variant also occurs in other breeds, as well as mixed-breed cats. Comparison of 31 affected and 58 healthy cats did not reveal significantly increased odds for HCM in homozygotes. Based on the combined evidence and in agreement with the standards and guidelines for the interpretation of sequence variants, this variant is currently classified as a variant of unknown significance and should not be used for breeding decisions regarding HCM.

Diagnosis and management of arrhythmias in dogs: A cross-sectional online survey among Flemish veterinary practitioners

Background

Diagnosis as well as management of arrhythmias in dogs can be challenging for veterinary practitioners. The aim was to describe ECG availability and use, as well as the diagnostic and therapeutic experiences and preferences of Flemish veterinarians regarding cardiac arrhythmias in dogs.

Methods

Cross-sectional online survey among veterinarians in Flanders (Belgium).

Results

An ECG device was available for 55 out of 102 respondents (54%) and 41 (43%) claimed to use it in case of arrhythmia suspicion. Insufficient knowledge about ECG interpretation and immediate patient referral upon detection of an abnormal heart rhythm were the most important reasons for not having, or not using, an ECG. About half of the respondents (56%) had never used anti-arrhythmic drugs in dogs, although only a few reported having had a negative experience. Frequently provided reasons for not using anti-arrhythmic drugs included insufficient knowledge and a low number of dogs with arrhythmias.

Conclusion

Most veterinarians reported having little or no expertise with arrhythmias in dogs. Electrocardiogram availability and use among respondents was moderate and too often restricted by insufficient ECG interpretation skills. Continued efforts are needed to increase the confidence and knowledge of veterinarians about arrhythmias in dogs.

Clinical relevance of serum electrolytes in dogs and cats with acute heart failure: A retrospective study

Background

Hypochloremia is a strong negative prognostic factor in humans with congestive heart failure (CHF), but the implications of electrolyte abnormalities in small animals with acute CHF are unclear.

Objectives

To document electrolyte abnormalities present upon admission of small animals with acute CHF, and to assess the relationship between electrolyte concentrations and diuretic dose, duration of hospitalization and survival time.

Animals

Forty‐six dogs and 34 cats with first onset of acute CHF.

Methods

Retrospective study. The associations between electrolyte concentrations and diuretic doses were evaluated with Spearman rank correlation coefficients. Relationship with duration of hospitalization and survival were assessed by simple linear regression and Cox proportional hazard regression, respectively.

Results

The most commonly encountered electrolyte anomaly was hypochloremia observed in 24% (9/46 dogs and 10/34 cats) of cases. In dogs only, a significant negative correlation was identified between serum chloride concentrations at admission (median 113 mmol/L [97‐125]) and furosemide doses both at discharge (median 5.2 mg/kg/day [1.72‐9.57]; r = −0.59; P < .001) and at end‐stage heart failure (median 4.7 mg/kg/day [2.02‐7.28]; r = −0.62; P = .005). No significant hazard ratios were found for duration of hospitalization nor survival time for any of the electrolyte concentrations.

Conclusions and Clinical Importance

The observed association between serum chloride concentrations and diuretic doses suggests that hypochloremia could serve as a marker of disease severity and therapeutic response in dogs with acute CHF.

Sudden cardiac death: A comparative review of humans, dogs and cats

Sudden death is one of the most common causes of death in humans in Western countries. Approximately 85% of these cases are of cardiac origin. In dogs and cats, sudden cardiac death (SCD) also commonly occurs, but fewer pathophysiological and prevalence data are available. Both structural, primarily 'electrical' and ischemic heart diseases are known to cause SCD, many of which share similar underlying arrhythmogenic mechanisms between humans and companion animals. As for underlying genetics, numerous mutations on multiple loci have been related to SCD in humans, but only a few mutations associated with dilated cardiomyopathy and SCD have been identified in dogs, e.g. in the phospholamban and titin genes. Information published from human medicine can therefore inform future veterinary studies, but also dogs and cats could act as spontaneous models of SCD in humans. Further research in both fields is therefore warranted to better understand the pathophysiology, genetics, and prevention of SCD.

The predictive value of clinical, radiographic, echocardiographic variables and cardiac biomarkers for assessing risk of the onset of heart failure or cardiac death in dogs with preclinical myxomatous mitral valve disease enrolled in the DELAY study

OBJECTIVES

To identify the predictive value on time to onset of heart failure (HF) or cardiac death of clinical, radiographic, and echocardiographic variables, as well as cardiac biomarkers N-terminal pro brain natriuretic peptide (NT-proBNP) and cardiac troponin I in dogs with preclinical myxomatous mitral valve disease (MMVD).

ANIMALS

One hundred sixty-eight dogs with preclinical MMVD and left atrium to aortic root ratio ≥1.6 (LA:Ao) and normalized left ventricular end-diastolic diameter ≥1.7 were included.

METHODS

Prospective, randomized, multicenter, single-blinded, placebo-controlled study. Clinical, radiographic, echocardiographic variables and plasma cardiac biomarkers concentrations were compared at different time points. Using receiving operating curves analysis, best cutoff for selected variables was identified and the risk to develop the study endpoint at six-month intervals was calculated.

RESULTS

Left atrial to aortic root ratio >2.1 (hazard ratio [HR] 3.2, 95% confidence interval [95% CI] 1.9-5.6), normalized left ventricular end-diastolic diameter > 1.9 (HR: 6.3; 95% CI: 3.3-11.8), early transmitral peak velocity (E peak) > 1 m/sec (HR: 3.9; 95% CI: 2.3-6.7), and NT-proBNP > 1500 ρmol/L (HR: 5.7; 95% CI: 3.3-9.5) were associated with increased risk of HF or cardiac death. The best fit model to predict the risk to reach the endpoint was represented by the plasma NT-proBNP concentrations adjusted for LA:Ao and E peak.

CONCLUSIONS

Logistic and survival models including echocardiographic variables and NT-proBNP can be used to identify dogs with preclinical MMVD at higher risk to develop HF or cardiac death.

Liver-type fatty acid-binding protein and neutrophil gelatinase-associated lipocalin in cats with chronic kidney disease and hyperthyroidism

BACKGROUND

Liver-type fatty acid-binding protein (L-FABP) and neutrophil gelatinase-associated lipocalin (NGAL) are candidate biomarkers for the detection of early chronic kidney disease (CKD) in cats.

OBJECTIVE

To evaluate urinary and serum L-FABP and NGAL concentrations in CKD cats and in hyperthyroid cats before and after radioiodine (¹³¹ I) treatment.

ANIMALS

Nine CKD cats, 45 healthy cats and hyperthyroid cats at 3 time points including before (T0, n = 49), 1 month (T1, n = 49), and 11 to 29 months after (T2, n = 26) ¹³¹ I treatment.

METHODS

Cross-sectional and longitudinal study. Serum L-FABP (sL-FABP), serum NGAL (sNGAL), urinary L-FABP (uL-FABP), and urinary NGAL (uNGAL) were compared between the 3 groups and between hyperthyroid cats before and after treatment. Data are reported as median (min-max).

RESULTS

CKD cats had significantly higher sL-FABP (13.50 [3.40-75.60] ng/ml) and uL-FABP/Cr (4.90 [0.97-2139.44] µg/g) than healthy cats (4.25 [1.34-23.25] ng/ml; P = .01 and 0.46 [0.18-9.13] µg/g; P < .001, respectively). Hyperthyroid cats at T0 had significantly higher uL-FABP/Cr (0.94 [0.15-896.00] µg/g) than healthy cats (P < .001), thereafter uL-FABP/Cr significantly decreased at T2 (0.54 [0.10-76.41] µg/g, P = .002). For the detection of CKD, uL-FABP/Cr had 100% (95% confidence interval [CI], 66.4-100.0) sensitivity and 93.2% (95% CI, 81.3-98.6) specificity. There were no significant differences in sNGAL and uNGAL/Cr between the 3 groups.

CONCLUSIONS AND CLINICAL IMPORTANCE

L-FABP, but not NGAL, is a potential biomarker for the detection of early CKD in cats. Utility of uL-FABP to predict azotemia after treatment in hyperthyroid cats remains unknown.

Transthoracic echocardiography and cardiac biomarkers in healthy captive male and female squirrel monkeys (Saimiri spp.)

Background

Echocardiography is the most frequently used non -invasive diagnostic tool to evaluate cardiac anatomy and function in domestic species but increasingly also in non -domestic species, especially since cardiac disease is being recognized as an important cause of death in captive primates. The purpose of this cross -sectional study was to investigate the feasibility of transthoracic echocardiography in healthy squirrel monkeys as well as to provide species specific normal values for standard echocardiographic measurements. A secondary aim was to determine plasma and serum levels of the cardiac biomarkers, N -terminal pro -brain natriuretic peptide (NT -proBNP) and cardiac troponin T (cTnT). Furthermore, a commercial, non -invasive, smartphone -based ECG (AliveCor Vet TM) monitoring device was used to evaluate the heart rate and rhythm and to diagnose possible arrhythmias.

Results

In this study, transthoracic echocardiography of 14 squirrel monkeys was performed in right and left lateral recumbency. Similar standard right parasternal and left apical images were obtained as in dogs and cats and normal values for routine two -dimensional, time motion mode and Doppler mode measurements were generated. Thirteen animals were considered healthy and one squirrel monkey was identified with significant aortic dilation and regurgitation and consequently values obtained from this animal were not used when species specific normal values were calculated. NT -ProBNP and cTnT concentrations were available for 7 of the 13 healthy monkeys with NT -proBNP concentrations below detection limit in all animals and a mean cTnT concentration of 0.049 ng/mL. Electrocardiography was performed in all squirrel monkeys. The mean heart rate was 172 bpm. Frequent supraventricular premature beats were diagnosed in the squirrel monkey suffering from significant aortic dilation and regurgitation.

Conclusion

This study presents echocardiographic normal values and additional cardiovascular data in anaesthetised Saimiri monkeys, fundamental from both the perspective of zoo animal health care as well as scientific research, since the squirrel monkey is often used as an animal model for human disease.

An overview of the current genetic and phenotypical selection strategies to reduce the prevalence of feline hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a common and potentially lethal heart disease in cats. To reduce its prevalence, breeding cats are frequently screened on the basis of their phenotype or genotype. Although echocardiography is the most reliable phenotypical method, its efficacy is limited by the incomplete penetrance of HCM and by difficulties in distinguishing primary HCM from other causes of left ventricular hypertrophy. On the other hand, genetic testing is hampered by the genetic heterogeneity of the disease. Genetic tests are currently only available for Maine Coons and Ragdolls. Because of the high prevalence of HCM, stringent selection may have a negative impact on the genetic diversity of a breed. A more optimal selection would therefore be a slow and careful exclusion of phenotypically and/or genetically positive cats.

DELay of Appearance of sYmptoms of Canine Degenerative Mitral Valve Disease Treated with Spironolactone and Benazepril: the DELAY Study

INTRODUCTION

Efficacy of renin-angiotensin-aldosterone system (RAAS) blockade using angiotensin-converting enzyme inhibitors (ACEi) in dogs with preclinical myxomatous mitral valve disease (MMVD) is controversial.

HYPOTHESIS

Administration of spironolactone (2-4 mg q 24 h) and benazepril (0.25-0.5 mg q 24 h) in dogs with preclinical MMVD, not receiving any other cardiac medications, delays the onset of heart failure (HF) and cardiac-related death. Moreover, it reduces the progression of the disease as indicated by echocardiographic parameters and level of cardiac biomarkers N-terminal pro brain natriuretic peptide (NT-proBNP) and cardiac troponin I (cTnI).

ANIMALS

184 dogs with pre-clinical MMVD and left atrium-to-aortic root ratio (LA:Ao) ≥1.6 and normalized left ventricular end-diastolic diameter (LVEDDn) ≥1.7.

METHODS

This is a prospective, randomized, multicenter, single-blinded, placebo-controlled study. Primary outcome variable was time-to-onset of first occurrence of HF or cardiac death. Secondary end points included effect of treatment on progression of the disease based on echocardiographic and radiographic parameters, as well as variations of NT-proBNP and cTnI concentrations.

RESULTS

The median time to primary end point was 902 days (95% confidence interval (CI) 682-not available) for the treatment group and 1139 days (95% CI 732-NA) for the control group (p = 0.45). Vertebral heart score (p = 0.05), LA:Ao (p < 0.001), LVEDDn (p < 0.001), trans-mitral E peak velocity (p = 0.011), and NT-proBNP (p = 0.037) were lower at the end of study in the treatment group.

CONCLUSIONS

This study failed in demonstrating that combined administration of spironolactone and benazepril delays onset of HF in dogs with preclinical MMVD. However, such treatment induces beneficial effects on cardiac remodeling and these results could be of clinical relevance.

Very painful acute frontal sinusitis revealing granulomatosis with polyangiitis

INTRODUCTION

Granulomatosis with polyangiitis (GPA) is a necrotizing vasculitis of small and medium-sized vessels comprising inflammation of the vessel wall and perivascular and extravascular granulomas, frequently presenting in the form of chronic sinusitis.

OBSERVATION

We report the case of a 27-year-old man who presented with very painful acute frontal sinusitis that was managed medically and surgically. The symptoms rapidly recurred despite treatment and CT scan demonstrated diffuse thickening of the sinus mucosa. Anti-proteinase 3 ANCA were positive. Biopsy of a pulmonary nodule confirmed the diagnosis of GPA. The patient was treated with corticosteroids in combination with rituximab, resulting in improvement of the clinical, laboratory and CT signs.

DISCUSSION

In the presence of persistent, acute, localized sinusitis despite appropriate treatment, associated systemic signs and/or the presence of other signs suggestive of GPA, the ENT surgeon must request a targeted work-up. In the absence of treatment, GPA can be fatal within a few months. However, with currently available treatment, remission is obtained in 80% of cases with a 75% 10-year survival rate.

Supraventriculaire tachycardie met isoritmische atrioventriculaire dissociatie bij een labrador-retriever

Een vrouwelijke, gesteriliseerde labrador-retriever van zeven jaar oud werd aangeboden met klachten van tachypneu, kokhalzen en abdominale distensie. Op het lichamelijk onderzoek werden een systolische hartruis met een intensiteit van 3/6 en punctum maximum links apicaal, tachycardie en zwak geslagen, femorale polsen opgemerkt. Een undulatieproef was positief. Na echocardiografisch en elektrocardiografisch onderzoek werden dilatorische cardiomyopathie (primair of secundair) en supraventriculaire tachycardie (SVT) vastgesteld. Na instelling van een behandeling met digoxine werd tijdens de opvolging een isoritmische atrioventriculaire dissociatie (IAVD) waargenomen en bleek de SVT onvoldoende onder controle gebracht. Na het overschakelen op diltiazem werd op het ECG vastgesteld dat de tachycardie onder controle was. Echocardiografisch onderzoek toonde aan dat het hart zich hersteld had. De hond vertoonde de daaropvolgende twee jaar geen cardiale symptomen meer. In deze casus wordt de zeldzame aritmie IAVD in combinatie met SVT beschreven. Daarnaast wordt het belang aangetoond van SVT als mogelijk reversibele oorzaak van een DCM-fenotype op echocardiografie.

Assessment of symmetric dimethylarginine as a biomarker of renal function in hyperthyroid cats treated with radioiodine

Background

Measurement of serum creatinine (sCr) and urea nitrogen fail to detect decreased renal function in many hyperthyroid cats because of low muscle mass and glomerular hyperfiltration of affected cats. Serum symmetric dimethylarginine (sSDMA) is an earlier and more sensitive renal biomarker than sCr.

Objective

Evaluate sSDMA as a biomarker of renal function in hyperthyroid cats before (T0) and 1 month after (T1) radioiodine (¹³¹I) treatment.

Animals

Forty‐seven client‐owned hyperthyroid nonazotemic cats were evaluated at T0 and T1.

Methods

A prospective study in which sCr and sSDMA concentrations were determined in 47 hyperthyroid cats at T0 and at T1. Glomerular filtration rate (GFR) was estimated at T0 and T1 in 10 of these 47 cats using plasma exogenous creatinine clearance test.

Results

Serum SDMA was elevated (>14 μg/dL) in 6 of 47 cats at T0 and normalized after treatment in 4 of those cats. All cats remained nonazotemic after treatment. In 10 cats in which GFR was measured, correlation between GFR and sSDMA was low and not significant (τ_b = −0.35, P = .17 at T0 and τ_b = −.22, P = .41 at T1), whereas correlation between GFR and sCr was moderate and significant (τ_b = −0.52, P < .05 at T0 and τ_b = −.53, P = <.05 at T1).

Conclusions and Clinical Importance

Careful interpretation of mildly increased sSDMA with normal sCr in hyperthyroid cats is warranted as sSDMA values might normalize after resolution of hyperthyroidism in some cats. In this population of hyperthyroid cats, sSDMA was poorly correlated with GFR.

Persisterende ductus arteriosus en pulmonalisstenose bij een labrador-retriever

Een drie maanden oude, vrouwelijke, intacte labrador-retriever werd doorverwezen wegens een vermoedelijk congenitaal hartprobleem. Klinische symptomen waren niet aanwezig, maar op het lichamelijk onderzoek werd een luide, continue hartruis met fremitus opgemerkt (graad 5 op 6) ter hoogte van de linkerhartbasis. Door middel van echocardiografie werd de diagnose van persisterende ductus arteriosus (PDA) en pulmonalisstenose (PS) gesteld. Anderhalve maand na de initiële presentatie werd de PDA chirurgisch gesloten. De PS werd medicamenteus behandeld met de ß-blokker atenolol en werd verder opgevolgd om de respons op deze therapie en de eventuele noodzaak van een ballonvalvuloplastie te evalueren. Deze casus toont aan dat een kwalitatief en volledig echocardiografisch onderzoek steeds noodzakelijk is bij een jong dier met een hartruis. Ook wanneer de oorzaak van de hartruis snel geïdentificeerd kan worden, in het voorliggende geval persisterende ductus arteriosus, moet er gecontroleerd worden op eventuele bijkomende afwijkingen, zoals hier pulmonalisstenose.

Thoracic radiography of healthy captive male and female Squirrel monkey (Saimiri spp.)

The purpose of this prospective study was to describe the normal anatomy and provide reference ranges for measurements of thoracic radiography on Squirrel monkeys (n = 13). Thoracic radiography is a common non-invasive diagnostic tool for both cardiac and non-cardiac thoracic structures. Furthermore cardiac disease is a common condition in captive primates. In this study, left-right lateral, right-left lateral and dorsoventral projections of 13 healthy Squirrel monkeys were reviewed during their annual health examinations. The mean Vertebral Heart Score on the left-right and right-left lateral projections were 8,98 ± 0,25 and 8,85 ± 0,35 respectively. The cardio-thoracic ratio on the dorsoventral projection was 0,68 ± 0,03. The trachea to inlet ratio was 0,33 ± 0,04. Other measurements are provided for the skeletal, cardiac and respiratory systems. Knowledge of the normal radiographic thoracic anatomy is fundamental in clinical as well as research settings for accurate diagnosis of diseases.

The Inhibiting Effect of a Plasma Globulin on Arterial Thrombus Formation (as Compared to Dipyridamole)

The inhibiting effect on arterial white thrombus formation of a globulin prepared from beef plasma has been compared to dipyridamole in white Wistar rats. It was demonstrated that the globulin fraction had a greater effect in inhibiting thrombus formation as judged by the lag time [t(1)], the maximal thrombus value [m(T)], the maximal thickness of the thrombus [m(D)] and the maximal thrombus surface [m(O)].

Feline arterial thromboembolism: prognostic factors and treatment

Feline arterial thromboembolism (ATE) is a complete or partial obstruction of a peripheral artery caused by a thrombus that was formed at a distant site. The most common underlying cause in cats is cardiomyopathy. Given the clinical presentation, often without preceding signs, an ATE event is considered one of the most distressing emergency conditions in feline practice. Often, these cats are euthanized at the time of diagnosis. However, recent scientific research has shown that a subpopulation of these patients may have long-term survival. In case of adequate treatment and follow-up, some cats survive over a year with a satisfying quality of life. Key points of ATE are the identification of specific prognostic factors in the individual patient in order to guide owner communication, the decision to treat or not to treat, individually adjusted patient management and regular monitoring, which are discussed in this article.

A single dose of intravenous combretastatin A4-phosphate is reasonably well tolerated and significantly reduces tumour vascularization in canine spontaneous cancers

Combretastatin A4-phosphate (CA4P) is an anti-tumour vascular targeting agent which selectively blocks tumour blood flow. Research on CA4P in rodent tumour models is extensive; however, knowledge of its effect on spontaneous cancer is scarce. This study was conducted in canine patients with spontaneous solid tumours. The goal was to assess the toxicity and efficacy of CA4P in various spontaneous tumour types. Eight dogs with spontaneous tumours were enrolled and treated with a single dose of 75 mg m^-2 intravenous CA4P. The dogs were screened and monitored before and after injection. Pre- and post-treatment tumour blood flow was analysed in vivo by power Doppler ultrasound (PDUS) and contrast-enhanced ultrasound (CEUS). Vessel destruction and tumour necrosis were evaluated by histopathology. Clinically relevant toxicity was limited to one case of temporary tetraparesis; other adverse events were mild. Significant cardiovascular changes were mostly confined to changes in heart rate and cTnI levels. Macroscopic tumour size reduction was evident in 2 dogs. Based on PDUS and CEUS, CA4P induced a significant decrease in vascular index and tumour blood flow. Post-treatment, histopathology revealed a significant increase of necrotic tumoural tissue and a significant reduction in microvessel density in tumoural tissue. Anti-vascular and necrotizing effects of CA4P were documented in a variety of canine spontaneous cancers with only minimal side effects. This is the first study reporting the administration of CA4P to canine cancer patients with in vivo and ex vivo assessment, and a first step toward implementing CA4P in combination therapies in veterinary oncology patients. The use of CA4P in canine patients was approved and registered by the Belgian Federal Agency for Medicines and Health Products (FAMHP) (approval number 0002588, registration number 6518 ID 2F12).

Tricuspid valve dysplasia in dogs

A general overview of tricuspid valve dysplasia in dogs is presented in this review. This congenital disease has been described in numerous large dog breeds but especially the Labrador retriever is predisposed. The condition is relatively uncommon, with a prevalence of approximately seven percent of all congenital heart diseases in dogs. The asymptomatic phase may last for several years and depends on the severity of the valve malformation. In the clinical phase, exercise intolerance, fatigue, anorexia, cardiac cachexia, dyspnea and signs of right-sided congestive heart failure can be present. Echocardiography including Doppler imaging is warranted to confirm the diagnosis. Curative treatment involves surgical valve replacement but is technically challenging and still in its experimental phase in dogs. As such, treatment in dogs involves the administration of supportive medication once the dogs develop symptoms of congestive heart failure and consists of diuretics, ace-inhibitors and positive inotropic drugs.

Predictors of Sudden Cardiac Death in Doberman Pinschers with Dilated Cardiomyopathy

Background

Doberman Pinschers with dilated cardiomyopathy (DCM) are at high risk of sudden cardiac death (SCD). Risk factors for SCD are poorly defined.

Aim

To assess cardiac biomarkers, Holter‐ECG, echocardiographic variables and canine characteristics in a group of Doberman Pinschers with DCM dying of SCD and in a DCM control group to identify factors predicting SCD.

Methods/Animals

A longitudinal prospective study was performed in 95 Doberman Pinschers with DCM. Forty‐one dogs died within 3 months after the last cardiac examination (SCD‐group) and were compared to 54 Doberman Pinschers with DCM surviving 1 year after inclusion. Holter‐ECG, echocardiography, measurement of N‐terminal prohormone of brain‐natriuretic peptide (NT‐proBNP), and cardiac Troponin I (cTnI) concentrations were recorded for all dogs.

Results

Volume overload of the left ventricle (left ventricular end‐diastolic volume (LVEDV/BSA) > 91.3 mL/m²) was the single best variable to predict SCD. The probability of SCD increases 8.5‐fold (CI_0.95 = 0.8–35.3) for every 50 mL/m²‐unit increment in LVEDV/BSA. Ejection fraction (EF), left ventricular end‐systolic volume (LVESV/BSA) and NT‐proBNP were highly correlated with LVEDV/BSA (r = −0.63, 0.96, 0.86, respectively). Generated conditional inference trees (CTREEs) revealed that the presence of ventricular tachycardia (VT), increased concentration of cTnI, and the fastest rate (FR) of ventricular premature complexes (VPC) ≥260 beats per minute (bpm) are additional important variables to predict SCD.

Conclusion

Conditional inference trees provided in this study might be useful for risk assessment of SCD in Doberman Pinschers with DCM.

Evaluation of Renal Perfusion in Hyperthyroid Cats before and after Radioiodine Treatment

Background

Hyperthyroidism and chronic kidney disease (CKD) are common in elderly cats. Consequently, both diseases often occur concurrently. Furthermore, renal function is affected by thyroid status. Because changes in renal perfusion play an important role in functional renal changes in hyperthyroid cats, investigation of renal perfusion may provide novel insights.

Objectives

To evaluate renal perfusion in hyperthyroid cats with contrast‐enhanced ultrasound (CEUS).

Animals

A total of 42 hyperthyroid cats was included and evaluated before and 1 month after radioiodine treatment.

Methods

Prospective intrasubject clinical trial of contrast‐enhanced ultrasound using a commercial contrast agent (SonoVue) to evaluate renal perfusion. Time‐intensity curves were created, and perfusion parameters were calculated by off‐line software. A linear mixed model was used to examine differences between pre‐ and post‐treatment perfusion parameters.

Results

An increase in several time‐related perfusion parameters was observed after radioiodine treatment, indicating a decreased blood velocity upon resolution of the hyperthyroid state. Furthermore, a small post‐treatment decrease in peak enhancement was present in the renal medulla, suggesting a lower medullary blood volume.

Conclusions and Clinical Importance

Contrast‐enhanced ultrasound indicated a higher cortical and medullary blood velocity and higher medullary blood volume in hyperthyroid cats before radioactive treatment in comparison with 1‐month post‐treatment control.

Vraag & Antwoord

Behandeling van mastitis met penicillinen en cefalosporinen Interpretatie van totaal T4-gehalte bij een acuut zieke hond