- Pulmonic stenosis (PS) is one of the most commonly encountered congenital cardiac defects in canine patients. English bulldogs have an increased risk of PS as compared to other dog breeds and have a higher reported prevalence of type II/type B/dysplastic pulmonic valve morphology. It has been shown that the dysplastic PS morphology may carry a more guarded prognosis and be less amenable to percutaneous balloon valvuloplasty (BV) procedures in canine and human patients. Due to the potentially decreased success of BV procedures in canine patients with a more dysplastic valvular phenotype, the ideal treatment for these cases may not be fully determined based on the currently published literature. There are breed predispositions observed with PS and French bulldogs may be more frequently affected with PS. Evaluation and characterization of the specific PS morphology observed in French bulldogs is lacking in veterinary medicine.
Case reports have provided evidence that English bulldogs and boxer dogs have an increased risk for anomalous coronary artery anatomy that may cause or complicate PS treatment. There is a possible association with coronary artery anomalies in the French bulldog breed, although information on prevalence in this breed is lacking in the currently available veterinary literature. The primary aim of this research study was to assess the pulmonic valve morphology and prevalence of coronary artery aberrancy in English and French bulldogs with severe PS (trans- pulmonic valve pressure gradient >80mmHg based on Doppler echocardiography) using echocardiography, angiography, and computed tomography (CT) imaging modalities. A secondary study aim was to evaluate demographic data for all English and French bulldogs with PS (mild, moderate, or severe) that presented to the Oregon State University Veterinary Teaching Hospital as compared to the population of non- bulldog breeds diagnosed with PS (mild, moderate, or severe) in the same time frame. These populations were further analyzed to specifically evaluate the bulldog and non- bulldog breeds with severe PS that underwent BV procedures. Data collection and evaluation included population characteristics, electrocardiography, echocardiography, and surgical records. A third study aim was to investigate BV procedural success and survival data between bulldog and non-bulldog breeds undergoing BV for severe PS.
Medical records were reviewed for French and English bulldogs presented to Oregon State University Veterinary Teaching Hospital (OSU VTH) for heart murmur evaluation or imaging prior to BV. Dogs were included if they had severe PS (pressure gradient >80 mmHg estimated via Doppler echocardiography) and confirmation of their coronary artery anatomy by either left-sided angiography or CT imaging. Echocardiographic, angiographic, and CT images were reviewed. The pulmonic annulus (PA), aortic annulus (Ao), PA:Ao and Ao:PA ratios, valvular anatomy, and coronary anatomy were assessed on each imaging modality by three observers (CS, KS, DDS) and averaged. The echocardiographic images were reviewed and measurements of right ventricular (RV) systolic function, chamber dimensions, and wall thickness were performed by 1 reviewer (CS). All non-bulldog breeds that were diagnosed with severe PS were also identified and echocardiographic data was assessed in the group that underwent BV procedures. Owners, referring veterinarians, or both were contacted to obtain outcome and survival information on all included patients to determine if they were alive/dead, date and cause of death if available, and if clinical signs of cardiac disease were observed. Data were tested for normality using the D’Agostino & Pearson omnibus normality test. Continuous variables were compared by Mann-Whitney U tests, ANOVA, or unpaired t-tests as indicated and categorical data was compared using a Fisher’s exact test. Survival times were calculated from the date of birth reported in the medical records to the date of natural death or euthanasia within the observational study period. Kaplan-Meier survival analysis was performed to compare cardiac and all-cause mortality.
The results of this study show that in the population of French and English bulldogs that presented to the OSU VTH, there was an increased prevalence of markedly dysplastic pulmonic valve morphology with the majority of cases displaying mild annular hypoplasia, which was different than the non-BD population. None of the French bulldogs (0/13) that underwent definitive coronary artery imaging had evidence of coronary artery anomalies while 6/8 English Bulldogs were definitively diagnosed with an R2A coronary artery anomaly. Within the group of dogs diagnosed with an R2A coronary artery anomaly, BV procedures were not performed in any of the patients and they had a poor mean long-term prognosis of 26 months. Indices of RV systolic function were decreased in the BD breeds in comparison to the non-BD breeds. There were significant differences observed in procedural success at the 1-month post-BV echocardiographic recheck and long-term follow up with the BD group having lower BV success than the non-BD group.
The results of this study indicate that BV performed on French and English bulldogs has a lower success rate then non-bulldog breeds. This lower success rate may be related to difference in valve morphology identified on echocardiographic, CT, and angiographic images. In addition, bulldogs appear to have a shorter survival time compared to non-bulldog breeds and this may be related to the differences in RV systolic function identified by echocardiography. Lastly, French bulldogs did not have the same high prevalence of anomalous coronary artery anatomy as English bulldogs in the population of dogs evaluated at the OSU VTH.