OBJECTIVES

Tricuspid valve dysplasia (TVD) is a congenital malformation of the right atrioventricular valve that may exist by itself or in combination with other congenital cardiac defects. The purpose of this study was to evaluate and describe the findings from cardiovascular examination in dogs diagnosed with TVD coexisting with other cardiovascular abnormalities

MATERIALS

Medical records from the Veterinary Teaching Hospital "Rof Codina" at the Lugo Veterinary Faculty, University of Santiago de Compostela (Spain), were searching for dogs with TVD that occurred in combination with other congenital cardiac defects diagnosed between January 1999 and January 2002.

During that period four dogs with echocardiographically confirmed TVD and concurrent congenital cardiac malformations were identified. Information was recorded for signalment, history, physical examination findings, electrocardiographic data, radiographic findings, echocardiographic results, pathologic findings and outcome for each dog.

RESULTS

Dog 1 was a 4-month-old 4 kg male Beagle that showed failure to grow and severe ascites. Echocardiographic studies revealed a TVD associated to a ventricular septal defect.

Dog 2 was a 9-month-old 15 kg female English setter that presented for a short history of respiratory problem. The combination of cardiac defects diagnosed in this dog was TVD, a well-developed cleft in the septal cusp of the mitral valve and a large ostium primun atrial septal defect.

Dog 3 was an apparently healthy 10-week-old 9,5 kg female German shepherd that had a heart murmur and cardiac arrhythmia detected during routine examination. The congenital heart defects detected in this dog were TVD, mitral valve dysplasia and persistent left cranial vena cava.

Dog 4 was a 6-month-old 2,2 kg female Yorkshire referred because of a heart murmur ausculted by its veterinarian after having suffered several syncopal events. A TVD coexisting with pulmonic insufficiency was detected on the echocardiogram.

CONCLUSION

TVD is an uncommon congenital malformation of the right atrioventricular valve. Although recent studies of congenital heart disease in dogs revealed that TVD is most commonly seen in large-breed dogs (>20 kg), small-breed dogs also may be affected as we have seen. TVD is not just a type of lesion. Rather, numerous abnormalities of the atrioventricular apparatus can occur. Leaflets, especially the septal leaflet may be fused directly to the right ventricular wall. Generally, this anomaly results in incompetence of the tricuspid valve and subsequent tricuspid regurgitation that leads to volume overload and marked dilatation of the right atrium and right ventricle. Tricuspid stenosis occurs rarely. Animals with severe TVD develop right heart failure. Although TVD most frequently occurs as an isolated defect, it may occur in combination with other congenital defects such as mitral valve dysplasia, atrial septal defect, ventricular septal defect, pulmonic insufficiency or persistent left cranial vena cava among others. When some of these concomitant defects are present the diagnosis of TVD is challenging due to the variability of associated clinical signs. These patients have complex cardiac disease and often have a poor prognosis.