To this point, hearing aids for dogs and other animals do exist but they remain limited to sound amplifiers. At this point, if an animals hearing is 100% lost, there is no hearing aid that can help.
In researching hearing aids for dogs, the trend seems to be that smaller dogs tolerate having the pieces in their ears better than larger dogs.
Something important to keep in mind is that most animals seem to show very little problems with becoming deaf and are able to rely on their other senses to help them out. Humans, it appears, seem much more reliant on our hearing than animals and in turn we need hearing aids more.
There is research being done into developing Cochlear implants and other hearing aids that would restore hearing for animals. I, however, question if these are actually needed!
