How long do ferrets live?

Why do ferrets tend to get masses beginning at age five? Aren't they supposed to live as long as nine years?

• Is it because of inbreeding? I heard a vet who put to sleep one of my ferrets last week (because of a mass) say that 95 percent of ferrets in the U.S. come from Marshall farms in New York. Why are ferrets so prone to masses and why don't they live longer?

• Answer:

  There is no single direct vector to the nature of ferret illness.  Marshall Farm's ferrets have, to the best of my knowledge, not had any formal study comparing their longevity or likelyhood of disease later in life to other genetic stocks as those found in England or Europe.  There is a strongly held belief that due to their limited breeding pool that inbreeding could in fact be playing a role in the prevalence of illness in American Ferrets.  However this has been disputed several times, and there is as to date no evidence beyond an apocryphal belief that this is 'true' by the greater community of pet owners.  It does not stand up to reason however when it is considered that the majority of the ferrets Marshall Farms produces are for genetic research, in which is more beneficial to have a wider genetic stock.  To my knowledge there has not been, to date, any large scale study of the genetic diversity of Marshall ferrets or any of the large scale ferret breeding colonies in operation anywhere. There are other factors to consider beyond breeding however which can lead to defects: Early Spaying and or Neutering, a standard practise for Marshall Farms ferrets, is believed to be linked to later health issues in a ferrets life cycle including tumors and adrenal disease.  Ferrets left 'natural' (as many are in the UK) do seem to enjoy a longer life time, however leaving a ferret unaltered can also have health consequences, particularly the risk of aplastic anemia in unmated females. Another likely culprit for ferret illness is owner mismanagement of the animal.  Ferrets have a very sensitive diet and cardiovascular system.  It responds poorly to excessive sugar, caffeine or alcohol.  Naturally of course, ferrets gravitate towards items with sugar, caffeine and alcohol.  Items which are normally found in a household like chocolate, mouth wash, unfinished cups of tea or coffee, will be eaten by ferrets, often with less than desirable results (vomiting, diarrhea) and prolonged lifestyles can lead to health risks.  Many commercially available ferret treats are in fact excessively high in sugar, not unlike 'junk food' for humans, and should be given only in limited amounts and infrequently.  If being used as rewards for training purposes, they should be broken up into several smaller pieces.  In many cases an owner may not even be aware their ferret has been 'sneaking in treats' as ferrets are notoriously good at sneaking, stealing and hiding items away before they are noticed.  Ferrets which are constantly given sugary treats also run the risk of tumors later in life. For an altered ferret a lifespan of 5-7 years would be 'average' with potential health issues usually appearing in years 4-6 in most cases.  There are statistical outliers on both ends, of ferrets who die young and also ferrets who live to what amounts to extreme old age for their breed.   It is worth noting that their wild cousins, the European and Eurasian polecats only have a life expectancy of around 5 years.