The ear is particularly susceptible to trauma and infection. Infection, more common in drop-eared breeds, may cause thickening of the tympanic membranes (ear drum) with resulting loss of hearing, or may affect the nerves leading to neural deafness in an otherwise normal ear. A drop ear is particularly attractive to ear mite, yeast, fungi and bacterial cultivation.
During aging, calcium deposits may form on the small bones (ossicles) resulting in conduction deafness. The inner ear provides the brain with sensory signals, which are processed into a sense of balance.
Occasionally, what appears to be a weakness in hind-quarters, is actually an ear problem disrupting balance. Even with none of the traumas and infections and other insults of life, the eardrum loses its ability to respond quickly to vibrations, hence, the common loss of hearing that comes with age.