Okay, I found it. This came from a brochure called "Ferret Facts" and then it says -compliments of Dr Susan Brown and Dr J A Neuman- This is a small excerpt in a several page long brochure: "Hair loss on the tail has been frequently observed in our area of the country (Midwest) and other areas, particularly in the fall of the year. The alopecia occurs only on the tail and may be total or partial. A reddish brown waxy deposit or black spots may also be present. We find that the condition resolves on its own in 1-3 months. No medications are necessary. This is probably a function of the adrenal gland in response to changes in the photoperiod. The true etiology is unknown." I will paraphrase a bit more of the brochure: Dietary problems do not generally lead to alopecia; skin parasites other than fleas are uncommon; the most common reason (95%) for hair loss in neutered pet is adrenal neoplasia but other causes have been granulosa cell, tumors, luteomas and fibrosarcomas in both intact and neutered animals; mast cell tumors of the integument have also been associated with alopecia, resolves when tumors are removed; in warm weather ferrets experience thinning of the coat, poor nutrition results in dry or sparse coats. Charlene [Posted in FML issue 1265]