People often think that if a dog is not born deaf, the dog will be OK. Certain breeds of dogs, those with the merle, piebald and harlequin coat colors, such as Dalmatians, Shetland Sheepdogs, Australian Cattle Dogs and Great Danes for example, have a high instance being born deaf. The Baer test on puppies born in these breeds can determine if a dog is deaf or not. However, dogs can suffer from hearing loss, much the same as people.
A dog can lose its hearing if the hair cells in the cochlea or if the eardrum and the small bones are damaged. Dr. Kari Foss, a veterinarian neurologist/professor at the University of Illinois at Urbana-Champaign, studied a gun dog, sniffer dog and a police dog and found that they had a hearing loss.

Hearing loss can result from being exposed to loud noises, illness and old age. In some cases, the hearing loss can be cured, such as those due to infections or illness.
Dr. Foss stresses that many people miss the signs that their dog is suffering from hearing loss. Dog owners should take note if their dog fails to respond when called, sleeping through sounds that they would normally respond to, being startled at loud noise that did not bother them before, barking excessively or making unusual vocal sounds. If a dog is deaf in one ear, they may have trouble locating the source of sounds.
If you suspect that your dog has a hearing loss, do not hesitate to make an appointment with your veterinarian. There is a chance that the problem can be corrected. However, if the loss is permanent, you can ensure that your dog stays safe by taking precautions. Dogs can live a safe and happy life even if they are deaf, or partially deaf.