Congenital Cardiac Disease in a Dog

Patient information:

Age: 1 year old

Species: Canine

Breed: Mixed Breed

Gender: Female – 9Kg

History:

Patient presented for failure to thrive and recent development of abdominal distension. A grade 5/6 systolic murmur was detected on auscultation. Heartworm test was negative. Thoracic radiographs were declined.

Echocardiogram interpretation:

The tricuspid valve was thickened especially the septal leaflet and the mural leaflet appeared tethered with moderate to severe tricuspid regurgitation. Right atrial and ventricular dilation were present with hypertrophy of the right ventricular free wall. The pulmonic valve was thickened with significant pulmonic regurgitation and pulmonary artery hypoplasia was evident. RV outflow tract velocities were elevated with a pressure gradient of up to 135 mmHg (severe over 80). Severe ascites was visualized.

Diagnosis:

Severe pulmonic stenosis and tricuspid valve dysplasia were present with secondary right ventricular hypertrophy and dilation, heart failure and moderate tricuspid regurgitation.

Images #1 and #2. Left - right parasternal long-axis 4-chamber view showing the right ventricle (RV) and atrium (RA) enlargement compared to the LV and LA, and hypertrophy of the right ventricular free wall (asterisk). Right - color flow Doppler showing the significant tricuspid valve regurgitation.

Image #3. Right parasternal short-axis view showing the significant thickening of the free wall and spectal leaflets of the tricuspid valve (arrows).

Image #4. Right parasternal short-axis view showing the pulmonic valve thickening (arrow), color flow Doppler of the pulmonic regurgitation and proximal narrowing of the pulmonary artery (PA).

Therapeutic recommendations:

Aggressive medical therapy for congestive heart failure was recommended as well as referral for balloon valvuloplasty as this procedure can improve longevity.

Outcome:

The client was informed that once heart failure is present, the outcome with balloon valvuloplasty is considered guarded and often prolongs survival by only 1 to 2 years. Due to the severity of the pet’s condition and poor long-term prognosis, the client opted for humane euthanasia.

Comments:

The literature suggests that fewer than 1% of dogs are affected by congenital heart disease. In two publications, pulmonic stenosis (PS) was the most frequently detected defect when combined cardiac malformations were present - 59.24% in 211 cases and 63.19% in 144 dogs. The combination of pulmonic stenosis and tricuspid dysplasia appears rare, being reported in only 3 out 976 dogs (0.3%) in one study.

Retrospective Review of Congenital Heart Disease in 976 dogs. Oliveira P et al. J Vet Intern Med 2011 May-Jun;25(3):477-83.

Epidemiological study of congenital heart diseases in dogs: Prevalence, popularity, and volatility throughout twenty years of clinical practice. Brambilla PG et al. PLoS One 2020 Jul 27;15(7):e0230160.

Special thanks to Dr. Simon Swift (DipECVIM - cardiology) and the staff at Banfield Urbana Pike for their help with this case.