I have a 6-7 year old Border Collie. The dog is very active and doesn't seem to be symptomic of anything much less cardiovascular disease. Recently, I noticed that she has an arrythmia which seems to be linked to respirations?. Maybe like a bigemeny or trigemeny pace. Again, I don't notice symptomatic behavior from the dog, no syncope, disorientation, excessive panting or exercise intolerance. Is it normal to have such a rhythm variance? Years ago, I had a dog sticken with heart worm and I noticed a simillar type of "thing". Regardless,thansk for the help.