Here's why:
* "Jills" (female ferrets) are induced ovulators: This means they only release eggs when they mate. If they don't mate, they can go into a prolonged estrus cycle called "jill heat," which can be fatal if untreated.
* Jill heat is very dangerous: It's a state of constant hormonal imbalance that causes bone marrow suppression, leading to anemia and potential death.
* Even spaying doesn't fully eliminate the risk: While spaying reduces the risk significantly, it doesn't eliminate it completely. Spayed jills can still experience mild jill heat, and some may still be receptive to mating.
It's much safer to keep female ferrets alone or in a neutered male/female pair.
If you're considering getting ferrets, be sure to research their care requirements carefully. You can find more information from reputable organizations like the Ferret Association of North America (FANA).