Elvis is a 5-year-old Doberman. When he was first presented, he had been treated with pimobendan for presumed dilated cardiomyopathy (DCM) by a preceding veterinarian.
What is DCM?
Dilated cardiomyopathy (DCM) is a type of heart muscle disease common in large breed dogs. In DCM, the heart muscle weakens and becomes dilated, resulting in reduced heart function and heart failure. Genetic mutations, such as in the PDK4 gene in Dobermans and Great Danes, predispose these dogs to DCM. Additionally, American Cocker Spaniels and Golden Retrievers may develop DCM secondary to taurine deficiency.
Diagnosis:
Electrocardiography (ECG) and echocardiography are two important diagnostic tools for evaluating DCM.
Early DCM (pre-clinical or occult) is often manifested by the presence of arrhythmias before echocardiographic abnormalities can be detected.
What happened to Elvis?
Upon examination, he was bright and alert, with a good body condition score (BCS: 5/9). A low-grade right heart murmur was detected.
The ECG showed an abnormal appearance of QRS complexes, but every QRS was preceded by a P wave. This suggested right bundle branch block (RBBB), a type of conduction abnormality. However, it differed from ventricular arrhythmias or atrial fibrillation, which are more commonly associated with DCM.
On echocardiography, the heart showed dimensions and function within normal limits. Trivial tricuspid regurgitation was present. However, cardiac dilations and reduced contractility were not observed.
Given the contradictory results, we decided to measure his serum N-terminal pro-B-type natriuretic peptide (NT-proBNP) level.
NT-proBNP is a cardiac biomarker, and an increased level suggests cardiac distension. In Dobermans, the cutoff point is 735 pmol/L.
Elvis showed a level of less than 500 pmol/L.
Combining the results above, a diagnosis of DCM was deemed unlikely, despite the presence of RBBB. The dosage of pimobendan medication was halved, and a review was scheduled in 3 months.
A subsequent review showed no remarkable clinical deterioration. The pimobendan medication was discontinued.
For more than 6 months after treatment cessation, Elvis is doing well.
