Hearing Impairment Brief Overview

Deafness in ferrets appears to have a strong correlation with "rare" or more praised coat patterns, such as blaze and panda, however, hearing impairment is not always easy to notice or diagnose. Ferrets are known for being extremely inquisitive animals and use all of their senses to understand an environment so even with a hearing impairment they may use vibration and visual cues more than simply hearing danger.

Indepth

Young ferrets with undiagnosed deafness may appear to be mentally deficient. While littermates run to play with an obnoxious loud toy our deaf subject may seem to be in their own word. Being young and not fully understanding the world yet young hearing impaired ferrets will often quickly become scared if picked up without notice. It is important with a ferret displaying those treats to give some visual cue that you are near - they often respond best to a slow hand movement - but they may still startle from this situation.  Thus, nip training becomes a very delicate process as a scared ferret should not be disciplined for nipping as that is a natural response. 

Another peculiar trait many owners report is how vocal their deaf companion is, often hissing or exhaling loudly with what appears as for no reason other than excitement. It may be that they are not aware of it, or some vibration generated by this they can hear and are trying to communicate, but likely they do not realise how loud they are.

Deaf ferrets find their own ways to communicate with groups of ferrets and can still bond, but may require human intervention when they do not get audible cues from a playmate. Since they can not hear the playmate hissing or crying they may not realise their playmate is concerned they may be food.