According to veterinarian Lee Pickett, 10% of dogs develop heart disease, mostly as they age. Of those dogs, 75% suffer from chronic valve disease, in which the heart valves degenerate over time, leaving the heart enlarged with compromised function. The disease is often first noticed as a heart murmur. Some veterinarians initiate treatment when X-rays show an enlarged heart, but others wait until additional signs develop. Dr. Pickett also outlines a disaster preparedness pet plan in this column.