My rottie had a spot that came and went. I took him to UGA, they said they see them with higher fat diets, had never seen them cause a problem, and that cholesterol in dogs.. well they just don't know if it is a problem but lower the fat if I wanted to. Since that was well over 12 yrs ago, I have no idea what the new thinking is but he lived to 12 (very old for a rottie) and never had an issue.
PPA… I am not a breeder. I am in no way an expert on or that knowledgeable about PPA. But I do know when Arwen, whom the breeder had told me was examined and eyes clear, had so many strands on arrival her eyes were blue. The ophthalmologist at UGA told me he hadn't seen strands that numerous in 2 decades, but none attached where likely to cause issues. I had her spayed. The breeder insisted I should still breed her. I told her she lied about the dog, she sent a dog we got to SHOW that was not ever going to be something I would breed and no, she would not be bred. I understand with limited gene pools you have to retain some problems.. but I really hope one day the breeders can start addressing issues such as excessive PPA, severe hernias etc.
And I agree with Pat, even if you can't see it, I really would have them examine him as they probably can.