Many dogs have fine, short hair in the ear canal, all the way down to the level of the ear drum. But certain breeds and their crosses grow so much long hair in their canals that it can cause trouble, especially if the ear becomes infected. Dog breeds that commonly grow excessive, long hair in their ear canals include the poodle (and crosses), the shih-tzu, Bichon Frise, and the Lhasa Apso.
Whether or not to remove the hair from the ear canals can be controversial amongst veterinarians and dog groomers. Most often, hair is removed by plucking that which is accessible with a hemostat or similar instrument. This will usually be done at a groomer or veterinarian’s office. As you can imagine, this procedure is uncomfortable and can lead to some inflammation. On the other hand, when the hair is left, it can trap normal ear wax and inflammatory debris which often develops with ear infections. A matt of hair and inflammatory debris in the canal will exacerbate an ear infection and render treatment less effective.
My recommendation for dogs with excessive ear canal hair is to remove the hair in the case of an ear infection but to avoid plucking in dogs with otherwise normal ear canals and that have no history of ear infections. If, however, the hair starts matting in the ear canal, it should be removed.