Humans have trouble with too much Vitamin A; ferrets and dogs have much with too much Vitamin D. On the other hand both ferrets and dogs handle large amounts of Vitamin A well, while humans handle large amounts of Vitamin D well as actually appear to need it. In fact, most people get less D than it is now thought that they should, partly because of not getting enough sun exposure (15 to 30 minutes a day should be sufficient in more locations if a person isn't stuck inside due to asthma temporarily). Vitamin D levels are now something that physicians regularly test for in annuals. Older people sometimes have trouble processing it, and I might be among those with my physician telling me that low levels are now thought to POSSIBLY be AMONG the triggers for a range of problems from some types of breast malignancies to MS. It is known to contribute to bone loss. The low D levels seen among U.S. children and the high levels of obesity with poor muscularity among U.S. children -- which both seem to relate to kids simply not getting outside to play actively for enough hours each day -- have many health experts very worried. Why would ferrets and dogs have more trouble with D but few if any problems with A, while humans can' not handle large amounts of A but appear to need high amounts of D? It lies in ancestry. Human ancestry involves long recent periods of being diurnal (active in the daylight) and sunlight on skin creates a lot of D. On the other hand, most human populations did not get a lot of A because of animal foods including organs that are high in A not being major components of the diet of our ancestors until very recently (and the body does not have to change all vegetable betacarotene that is ingested to A). Ferrets are the opposite. Their ancestors were crepuscular -- meaning most of their activity was in the low light periods of dawn and dusk. Otherwise, they mostly were in extremely dark burrows. In addition, having a dense fur coat does not exactly predispose a population to having to survive high D levels to successfully reproduce down the generations. D3 is especially a problem for ferrets. Their diets included whole animals -- plenty of livers, for example -- so they had to be able to survive high levels of A to successfully reproduce down the generations. So, it is important to not take what is written for humans in relation to these two nutrients and apply it to ferrets or you could wind up with an undernourished one in relation to A who might also be more vulnerable to Canine Distemper See: http://ferrethealth.org/archive/FHL9600* http://ferrethealth.org/archive/FHL9659 http://ferrethealth.org/archive/FHL9578 or who has hypercalcemia from too much D3 See: http://ferrethealth.org/archive/FHL7405 http://ferrethealth.org/archive/FHL5264 though this rare problem improved with a D analog: http://ferrethealth.org/archive/FHL3280 and Vitamin D poisoning is being considered as a reason why grapes and raisins can poison ferrets, cats, and dogs with acute kidney failure resulting, but have not done so for humans: http://ferrethealth.org/archive/FHL9247 May also be of interest in relation to ferret nutrition: http://ferrethealth.org/archive/FHL8493 http://ferrethealth.org/archive/FHL7988 http://ferrethealth.org/archive/FHL9769 http://ferrethealth.org/archive/FHL7810 http://ferrethealth.org/archive/FHL7777 http://ferrethealth.org/archive/FHL4048 http://ferrethealth.org/archive/FHL8279 Sukie (not a vet) Recommended ferret health links: http://pets.groups.yahoo.com/group/ferrethealth/ http://ferrethealth.org/archive/ http://www.afip.org/ferrets/index.html http://www.miamiferret.org/ http://www.ferrethealth.msu.edu/ http://www.ferretcongress.org/ http://www.trifl.org/index.shtml http://homepage.mac.com/sukie/sukiesferretlinks.html all ferret topics: http://listserv.ferretmailinglist.org/archives/ferret-search.html * The amounts below are CORRECT. See: http://ferrethealth.org/archive/FHL9659 to verify that. >J Nutr. 2007 Aug;137(8):1916-22. >Disease manifestations of canine distemper virus infection in >ferrets are modulated by vitamin A status. > >Rodeheffer C, von Messling V, Milot S, Lepine F, Manges AR, Ward BJ. >McGill University Health Centre Research Institute, Faculty of >Medicine, Division of Infectious Diseases, Montreal General Hospital, >Montreal, QC, Canada. > >The measles virus (MV) causes half a million childhood deaths >annually. Vitamin A supplements significantly reduce measles- >associated mortality and morbidity. The mechanisms whereby vitamin >A acts against MV are not understood and currently there is no >satisfactory small animal model for MV infection. We report on the >development of a ferret model to study antiviral activity of vitamin A >against canine distemper virus (CDV). CDV is closely related to MV at >the molecular level and distemper in ferrets mimics measles in humans. >We infected vitamin A-replete (control) and vitamin A-depleted >ferrets with CDV and assessed the ability of high-dose vitamin A >supplements to influence CDV disease. In control ferrets, CDV >infection caused fever, rash, conjunctivitis, cough, coryza, and >diarrhea. In contrast, control ferrets that were given 30 mg of >vitamin A did not develop typical distemper after infection and >exhibited only a mild rash. The supplement did not negatively affect >ferret health and resulted in a 100% increase in serum and liver >vitamin A concentrations. We also found that profound vitamin A >deficiency is inducible in ferrets and can be rapidly reversed upon >high-dose vitamin A supplementation. Vitamin A deficiency caused >anorexia, diarrhea, cataracts, behavioral abnormalities, and >ultimately death, with or without CDV infection. All ferrets that >received vitamin A supplements, however, recovered uneventfully >from CDV infection. These results replicate many aspects of the >observations of vitamin A therapy in humans with measles and suggest >that CDV infection in ferrets is an appropriate model for the study >of the antiviral mechanism of vitamin A. > > PMID: 17634264 > > The full article is HERE: > http://jn.nutrition.org/cgi/reprint/137/8/1916 [Posted in FML 6476]