Translation:This dog is the father of the puppies you saw.
Quote: "The only time you will have an agreement with avoir is when there is a direct object preceding the past participle." In this case, "des chiots" is the direct object (you saw the puppies) and it precedes "... as vu", so change it to " as vus". Here's another example: "La voiture que j'ai achetée est noire." - acheté (past participle) must be changed to achetée to agree with la voiture. I usually pay close attention whenever I see "que" before the verb. Hope this helps.