Background: To date, epidemiological studies on degenerative mitral valve disease (DMVD) in dogs have largely reported referral caseloads or been limited to predisposed breeds. Analysis of primary-care data to identify factors associated with DMVD would help clinicians identify high-risk individuals and improve understanding. Objectives: To estimate the prevalence of and identify risk factors for DMVD in dogs attending primary-care veterinary practices in England. Animals: Cases were identified within the electronic patient records of 111,967 dogs attending 93 practices. Four hundred and 5 dogs were diagnosed with DMVD (diagnosed cases) and a further 3,557 dogs had a heart murmur (HM) consistent with DMVD (possible cases). Methods: Retrospective cross-sectional study design. Prevalence was adjusted for the sampling approach. Mixed effects logistic regression models identified factors associated with DMVD. Results: Prevalence estimates of diagnosed DMVD and HMs consistent with DMVD (both diagnosed and possible cases) were 0.36% (95% confidence interval [CI]: 0.29–0.45) and 3.54% (95% CI: 3.26–3.84) respectively. In the multivariable analysis, males had higher odds of diagnosed DMVD than did females (odds ratio [OR] 1.40, 95% CI: 1.12–1.74). Insured dogs had increased odds of DMVD compared with noninsured dogs (OR 3.56, 95% CI: 2.79–4.55) and dogs ≥20 kg had approximately half the odds of DMVD diagnosis compared with dogs <20 kg (OR 0.51, 95% CI: 0.36–0.74). Strong associations between a DMVD diagnosis and individual breeds and age were identified. Conclusions and Clinical Importance: Degenerative mitral valve disease was a common disorder in practice-attending dogs. Knowledge of identified risk factors for DMVD could improve clinical diagnosis and direct future research.

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.

Background: Several risk factors already have been determined for dogs with degenerative mitral valve disease (DMVD). Risk factors often have been considered in isolation and have not always taken into account additional information provided by the history and physical examination (PE). Hypothesis/Objectives: Data obtained from history and PE of dogs with DMVD provide prognostic information and can be used for risk stratification. Animals: Client-owned dogs (n = 244) with DMVD recruited from first opinion practice. Methods: Prospective longitudinal follow-up of dogs with DMVD. History and PE data were obtained at 6-month intervals and analyzed with time-dependent Cox models to derive relative risk of cardiac death. Independent hazard ratios were used to derive a clinical severity score (CSS), the prognostic value of which was evaluated by analyzing the median survival times for different risk groups and ROC analysis. Analysis of the progression of CSS over time also was undertaken. Results: History of cough, exercise intolerance, decreased appetite, breathlessness (difficulty breathing) and syncope with PE findings of heart murmur intensity louder than III/VI and absence of respiratory sinus arrhythmia were independently associated with outcome and allowed development of the CSS. Clinical severity score distinguished groups of dogs with significantly different outcomes. Conclusions and Clinical Importance: Routinely obtained clinical findings allow risk stratification of dogs with DMVD. Results of ancillary diagnostic tests may be complementary to history and PE findings and always should be interpreted in conjunction with these findings.

Background: Increased heart rate (HR) and decreased heart rate variability (HRV) are evident in some dogs with degenerative mitral valve disease (DMVD). Objectives: Evaluation of the factors influencing HR and HRV (assessed by the vasovagal tonus index; VVTI) and their change over time in dogs with DMVD. Animals: Client-owned dogs (n = 257) with DMVD recruited from first opinion practice. Methods: Prospective longitudinal follow-up at six-monthly intervals of dogs with DMVD. Dogs followed up for at least 18 months (n = 102) were grouped according to their outcome as dogs dying/euthanized because of cardiac disease (n = 28; Group 1), noncardiac disease (n = 40; Group 2) and dogs alive (n = 34; Group 3). HR and VVTI were measured on 1-minute ECG recordings. Repeated measures linear models were constructed to investigate the factors that influence HR and VVTI and their changes over time. Results: Heart rate and VVTI were affected by disease severity and were different in Cavaliers compared to other breeds. Group 1 and Group 2 dogs underwent an increase in HR and decrease in VVTI, evident at least 18 months before death. Group 1 had a further decrease in VVTI followed by an increase in HR approximately 1 year and 6 months before death, respectively. Conclusions and Clinical Importance: Dogs with DMVD have an increase in HR and decrease in HRV over a year before death, with greater changes in those dogs dying/euthanized because of cardiac disease. Both HR and VVTI can potentially be regarded as biomarkers for all-cause mortality.