Familial ventricular arrhythmias in boxers

The purposes of this study were to evaluate families of Boxers with ventric ular arrhythmias to determine whether this disorder is a familial trait: an d, if so, to determine the mode of inheritance. Eighty-two Boxers were eval uated by physical examination, electrocardiogram, echocardiogram, and 24-ho ur ambulatory electrocardiogram. Dogs were considered affected if at least 50 premature ventricular complexes (PVCs) were observed during a 24-hour pe riod. All dogs were at least 6 years of age at evaluation. Complete cardiov ascular examinations were performed on dogs from 6 extended families. The 2 most complete pedigrees were used to determine the pattern of inheritance. The number of PVCs observed during a 24-hour period in affected dogs range d from 112 to 4,894 (mean +/- SD, median; 1,309 +/- 2,609, 1,017). The numb er of PVCs observed during a 24-hour period in the unaffected dogs ranged f rom 0 to 16 (7 +/- 10, 12). Pedigree evaluation was performed to determine pattern of inheritance. An autosomal dominant pattern was determined to be most likely because a sex predisposition was not observed, affected individ uals were observed in every generation, and 2 affected individuals produced unaffected offspring. We conclude that familial ventricular arrhythmias is inherited as an autosomal dominant trait in some Boxers.