The best replacement for ferrets is rats.

The best alternatives to ferrets are rated as following:
★★★★★  rats
★★★★  chinchillas
★★★  weasels
★★★  guinea pigs
★★  rabbits
★★  sugar gliders
  male ferrets
  wolfbats
  skunks
  minks
  packing peanuts
  female ferrets

Your alternative for ferrets is not listed? Suggest!
Speaking about ferrets, one probably shouldn't forget about adrenal disease.

Other search terms related to ferrets and their ratings are:
★★★★★ adrenal disease
You have in mind a companion for ferrets and it is not yet here? Propose!



Google Trends

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ferrets
rats
chinchillas