I have learned from the Internet and from vets that there are no universally accepted formal hearing tests for ferrets.
I have read that the University of Ohio State can perform formal hearing tests, they however can be rather complex and even
traumatic for the ferret. So the best that a ferret owner or vet can do are some simple tests that can be performed even in the
home. You'd be surprised how reliable home tests can be.
There are many, many ways to test a ferret for deafness. Before I list a few ways let me preface this by reminding you of a few things. Always remember that ferrets are intelligent and extremely astute. In a hearing impaired ferret, the rest of the senses [smell, sense of touch, etc,] are all heightened. Test a ferret without any other ferrets around. Test in a room with low stimulation and little distraction. When you test a ferret, make sure you do so without involving vibration.
|Do NOT: use a vacuum cleaner, hit the cage, stomp on the ground, or do anything that will allow them to feel a vibration.|
|Also when testing, even though a ferret's eyesight is supposedly
not very keen, make sure there are no visual cues. Believe me the ferret's eyesight is keen enough to see other ferrets react,
people react, or see movement of any sort.
Also remember there are many levels and types of deafness. Some ferrets may just be partially deaf in that they may be able to hear only certain frequencies.
You can start with a simple test using a squeaky toy. Ferrets innately react to squeaky toys much of the time because they sound like kits calling out.
** Stand near the ferret and have the toy behind your back and don't let the ferret know you have it. Once his head/back is turned, squeak it and see if the ferret turns its head in any way.
** Do the same thing again, only try using a different sound like clapping. Wait until the ferret turns its back and clap loudly right behind it and see if it reacts (don't clap too closely as the ferret will feel the breeze from your hands, or see your movement).
** Try using things with varying tones and frequencies (keys, bell, squeak toy, clapping, etc).
** Another thing to try is if your car is within hearing distance, open the door or window, and have a friend go outside and beep the car horn. I've found ferrets sometimes react to distant horns, even if they have trouble reacting to other sounds (hence partial deafness in that case).
** The biggest test of all is the old "pennies in a coffee can" trick. Once again, stand near the ferret with the can of pennies hidden. When the ferret turns its back and can't see, shake the can hard. Any ferret should jump at this one.
If you have a ferret that passes such tests, but you still suspect deafness, there is a pretty sure-fire way to test those ferrets.
** Get a cat toy with a bell in it, or a squeaky toy, and Ferretone, Furotone, or Linatone, or any treat your ferret loves. Make a noise with the toy and immediately give the ferret a treat. Do this several times a day for about a week or so. After you feel as if you've done this consistently enough for long enough, then you can really test them.
** Hide the toy, then when the ferret isn't looking make some noise with the toy. Wait and see if the ferret turns and comes to you for their treat. A normal ferret will be conditioned to react and even come to you each time you make noise with that toy to get a treat.
As I said, the ways to test a ferret for hearing are limitless. I hear of great ideas all the time. I just listed the easiest and probably the most common ways to test a ferret. The key thing is to be smart. Test them without anything or anyone else giving the cues, and with out other distractions.
It is virtually impossible to test a ferret in the chaos of a pet store with other ferrets around and all the other distractions. You can still try, with experience and practice it is possible, though not reliable. The best thing to do is to ask the pet store if you can see the ferret in a private room. Let the ferret have a good look and sniff around first. Because the ferret will be over excited and anxious, this is still not a reliable way. Home testing in this environment may give you false positive results (it may look like a ferret is deaf when he/she is not), BUT if you can get the ferret to react much of the time this is a pretty sure way to know that he/she can hear.