Sinus bradycardia (SB) means a slower-than-normal rate of impulses in the sinus node. The sinus node or the sinoatrial node (SAN) generates electrical impulses in the heart causing the heart to beat. In most cases, slow sinus electrical impulses is benign and may even be beneficial; however, it can also cause loss of consciousness if it is due to an underlying disease that disrupts the cardiac nerves.
SB is fairly common in dogs, especially in cocker spaniels, dachshunds, pugs, West Highland white terriers, and female miniature schnauzers. In addition, this condition is more common in young dogs than old, with the incidence decreasing with age, unless it is being caused by an underlying disease.
The dog may display no symptoms specially if it is very active. Typically, the sinus bradycardia is most apparent when your dog is at rest.