The male ferret (hob) can weigh up to 2 kg, with an average weight of 1.2 kg. The female (jill) can weigh up to 1.2 kg, with an average weight of 0.8 kg. Sexual maturity is reached at 4–8 mo and occurs in the first spring after birth. The vast majority of ferrets are spayed or neutered before 6 wk of age primarily because females are induced ovulators and can develop severe hyperestrogenemia if not bred. Ferrets also have less of the musky smell that is characteristic of Mustelids if they are gonadectomized early in life. The anal scent glands are usually removed when they are neutered/spayed. Most physiologic data for ferrets are similar to those of the domestic cat. Ferrets require high levels of fat and protein in the diet and should be fed commercial ferret food or high quality cat or kitten food. Most adult ferrets have a large spleen. This is usually caused by extramedullary hematopoiesis and is nonpathogenic; ultrasonography and aspiration can be used for a definitive diagnosis.
Ferrets are vaccinated annually for rabies and canine distemper. There is one FDA-approved rabies vaccine for ferrets in the USA. It should be given to ferrets >16 wk old and repeated annually. If this vaccine is unavailable, an inactivated vaccine of murine origin should be substituted. Canine distemper vaccines for ferrets should be of chick embryo or recombinant origin. Vaccines of mink or ferret culture (eg, most multivalent vaccines for dogs) should not be used as they may cause seroconversion and disease. There are currently 2 FDA-approved distemper vaccines in the USA for ferrets. Ferrets should be vaccinated at ~8, 10, and 12 wk of age and then yearly. Vaccine reactions occur frequently in ferrets and it is recommended that vaccinated animals be monitored for 20–30 min following vaccination, and that only one vaccine (ie rabies or distemper) be given at a time. Ferrets raised commercially are often vaccinated for Clostridium botulinum type C at 6–8 wk old.
Last full review/revision July 2011 by James K. Morrisey, DVM, DABVP (Avian)