A pedigree-based genetic appraisal of Boxer ARVC and the role of the Striatin mutation.

The objective of this paper was to investigate by pedigree-based genetic means the origins and inheritance of arrhythmogenic right ventricular cardiomyopathy (ARVC) in UK Boxers and assess the role of the proposed causal mutation in the gene, Striatin (STRN). All ARVC cases traced back to a small number of imported American dogs deriving from the group of Boxers studied by Harpster (1983) to define the disease, strongly suggesting that the disease is the same in the two countries. Dogs with and without the STRN mutation were found in both ARVC affected and normal Boxers showing that the mutation is not responsible for the disease. Evidence was found that the STRN mutation is, however, genetically linked with the gene responsible on the same chromosome. The linkage implies that the two genes can separate by meiotic recombination such that both ARVC-affected and ARVC-unaffected lines of dogs may carry either the STRN mutation or its wild-type allele. These have been found. Homozygotes for the STRN mutation tended to be severely affected at early ages, suggesting that there is an interaction between the known effects of the STRN mutation on the cardiomyocyte and ARVC.

Left atrial size, atrial function and left ventricular diastolic function in cats with hypertrophic cardiomyopathy.

OBJECTIVES: To describe left atrial size, left atrial volume, left atrial function and left ventricular diastolic function in healthy cats and those with hypertrophic cardiomyopathy without and with congestive heart failure. METHODS: A retrospective study of 61 client-owned, 21 healthy, 21 asymptomatic hypertrophic cardiomyopathy and 19 with hypertrophic cardiomyopathy and congestive heart failure cats. Data were retrieved from clinical records and echocardiography archives. Left atrial diameter and volumes were measured. Left atrial function was investigated using changes in diameter (fractional shortening) and volume (Simpson's method; left atrial ejection fraction). Conventional echocardiographic indices of left ventricular diastolic function were recorded. RESULTS: Left atrial diameter and left atrial volume measurements were significantly higher in hypertrophic cardiomyopathy with congestive heart failure cats compared with asymptomatic hypertrophic cardiomyopathy and healthy cats (P < 0·001). Left atrial passive, active and complete ejection fraction distinguished between hypertrophic cardiomyopathy with congestive heart failure and asymptomatic hypertrophic cardiomyopathy (P < 0·001). Hypertrophic cardiomyopathy with congestive heart failure cats had significantly lower mitral A wave velocity (P = 0·016) and atrial complete emptying based on diameter and volume measurements (P = 0·008 and P < 0·001, respectively) compared with asymptomatic hypertrophic cardiomyopathy cats. CLINICAL SIGNIFICANCE: Left atrial volume is obtainable by echocardiography in cats. Left atrial volume and atrial function may indicate chronicity and severity of diastolic dysfunction associated with hypertrophic cardiomyopathy and congestive heart failure. Left atrial function was reduced in cats with hypertrophic cardiomyopathy and congestive heart failure compared with healthy and asymptomatic hypertrophic cardiomyopathy groups.

Screening for dilated cardiomyopathy in Great Danes in the United Kingdom.

BACKGROUND: Great Danes (GD) are predisposed to dilated cardiomyopathy (DCM), but little is known about progression, clinical manifestations, or inheritance in dogs in the UK. For echocardiographic screening, breed-specific reference intervals (RI) are required. OBJECTIVES: To document the prevalence, clinical manifestations, and inheritance of DCM in UK GD. To establish RI for Doppler echocardiography (ECHO) in GD. ANIMALS: One hundred and seven client-owned GDs. METHODS: Echocardiographic screening study. Dogs were scored on ECHO and ECG variables and classified as normal (NORM), equivocal (EQUIV), or affected (AFX). Forty NORM dogs were used to determine RI for ECHO. Pedigrees from all dogs were examined for mode of inheritance. RESULTS: The prevalence of DCM in this population, based on score, was 35.6%. Significant differences in M mode left ventricular dimensions (MMLVD) were identified between male and female dogs (P < .011). RI for MMLVD and transformed MMLVD (allometric scaling) were lower than previously suggested. When dogs were reclassified using amended RI for MMLVD, prevalence increased to 47%. End-systolic volume index more reliably identified AFX dogs than other systolic function indices. Ventricular arrhythmias (VA) were commonly identified, with the highest prevalence in AFX dogs (54%). Pedigree analysis suggested an autosomal dominant mode of inheritance. CONCLUSIONS AND CLINICAL IMPORTANCE: The prevalence of DCM in UK GD is higher than previously reported and autosomal dominant inheritance is likely. Sex or body weight-dependent RI should be used for ECHO in GD and current RI might underestimate ESVI in GD. VA might play an important role in GD with DCM.