There had been a hypothesis that there might be later heart effects from vaccine reactions but this has not panned out. As you can well suspect with multiple past ferrets and people on both sides of our family who get anaphylactic reactions it was something that I wanted to check so I checked a few years ago not only with vets (one of whom said "interesting hypothesis but no proof" and others just said "no proof") but also with allergists and cardiologists. I was told that there is no known connection and was even told by one cardiologist that he doubted that there would be a connection, especially compared to everyday things. So, as it stood when I asked around there was a hypothesis but it still lacked proof and it had its strong doubters. I can tell you that our families have not been told of ANY problems for which we are at increased risk due to these reactions beyond the reactions themselves being dangerous, eye damage from the levels of steroids sometimes used when combined with ocular hypertension or a tendency toward glaucoma, and possible cardiovascular risks from the medical routine if heart disease is already present (but I haven't heard the last mentioned for quite a large time -- decades -- so I don't know if that is still considered a caution despite the medical response being needed). Of course, if a reaction is not treated soon enough or hard enough then it is possible for brain damage to occur (which I personally find scarier than dying). I suspect that if any definite connection is made to further health concerns I'll be told about them by my physicians since one of them has seen me react, and other family members who have been witnessed reacting will be told by other physicians, but so far that is it. That help? I'm very sorry to read of Sprinkles' malignancy. Since Sprinkles began with dark patches and later turned white (roaning), Sprinkles *genetically* is not a true dark eyed white but is a marked white who roaned. Thanks for giving the opportunity to point out something important which causes confusion repeatedly: that later markings are altered ones (due to a variety of causes including genetic causes that cause lightening). The failure to distinguish between these often causes problems for following up on rates of some attached medical problems. For instance a blaze( a type of head marking) that later roaned to have a white head would be just that: a genetic blaze who roaned to a panda rather than just being a panda when a person is trying to follow up on attached medical problems. I know that you were just referring to the markings, but this is a point of confusion which has complicated many attempts to follow-up on such things and you brought up such a good way to mention this which may help others. [Posted in FML issue 4117]