As I explained in the FHL (and folks who wanted to see the full thing could have looked there and followed the conversation as it unfolds) the treating vets and also so far all of the consulting vets are implicating diet. With cystine stones there is a second implicated cause in some mammals (which is confirmed as an existing hypothesis by a human urologist who is friend) which is diet related. Again: http://www.smartgroups.com/message/readmessage.cfm? gid=1423922&messageid=9504&startid=9520 Discussions on this have been going on quietly with vets for a few weeks, and more so when we got the results, which -- although they were not the expected results -- had been talked about and somewhat looked into but then looked into much more seriously when the results came in including many discussions with knowledgeable ferret vets. What is too much protein for a ferret and how much do individuals differ? No one knows, but it does appear that folks need to take some things into account, including: 1. that moderation is a logical approach once we finally know what moderation actually is in this regard because there just isn't enough info to know yet what levels may be optimal, 2. that stones need to be considered of there are signs of difficulty urinating, of a UTI, or even of straining to defecate and difficulty passing stools with actual constipation or thin stools but no GI blockage present (since that was the first presentation for both due to general inflammation and all) and if found need to be tested rather assumed to be struvite stones, 3. that we as a group may be seeing more of these as higher protein diets become more common, or it may be that only certain types of foods get involved so ones using those particular foods might be more likely to get them so it pays to be aware of the possibility for optimum safety if a ferret takes ill, and 4. that there may be more of these than thought but the needed pathology isn't being done or the ferrets aren't being caught in time. If there are more than thought then the equation changes but the precautions and responses once such an individual is encountered are at least available in http://fhl.sonic-weasel.org for those who may need them, no matter how common or rare they may be. As has been said may times by many vets: ferrets are not dogs, are not cats, are not humans, etc. So often enough the best approach is to be aware that a situation which might call for awareness has been found even when there is too little info to know better what the boundaries or particulars are. You'd be amazed at how many ferret health problems have made very real progress in people understanding them due to those who encounter them making the info available and someone finally putting things together from that after enough cases happen: from finding and tracing a coccidia variant that was hard to get but fatal when caught and stopping it by isolating the areas and treating (no joke -- the FML years ago was essential in the ground work which stopped that epizooic), or putting together patterns for ECE, or noticing things about a wide range of other medical problems. There have even been vet articles on how the internet helped ferret medicine progress. Whether the stones we had to deal with (and which hopefully will stop now) will fall into the category of something which can be of use to others in writing about them and having others who may run into them over time also write here isn't possible to know at this point. Only time will tell. We are aware of the the one proven cause (which the vets consider unlikely, but of course, odds are beaten all the time in bad ways as well as good ones, it's just that they are beaten by very few individuals), and we are also aware of the hypothesis which the vets consider more likely in this situation. Time and sharing will likely the only ways to sort out just what exactly is going on. Meanwhile, it never hurts to remember that there really is close to nothing which doesn't have both upsides and downsides. [Posted in FML issue 4570]