More reasons to spay

I spayed an older dog the other day.  The owner reported no known issues but during surgery her left ovary happened to be the size of a small orange.  After surgery I cut it open and found it to be full of cysts.  I have no idea if this was bothering the dog or not but I'd hate to think that if it does and we don't know about it there could be a bunch of intact dogs walking around with painful ovaries.  I have seen this condition in both dogs and cats but this is the most extreme example I have found.  This dog was only 22 lbs by the way.