The reason why dogs bite their ears may be out of curiosity or because they want to clean their ears. Dogs sometimes use their tongues to clean their ears, but if there are parasites or dirt in their ears, they may use their teeth to help clean them. Dogs may also bite their ears because they feel discomfort or pain. For example, if your dog has parasites or an infection in their ears, they may bite their ears to relieve the pain.
If your dog often bites its ears or is accompanied by other abnormal symptoms, it is recommended that you take your dog to see a veterinarian. In addition to the above reasons, dogs may also bite their ears because they are threatened or nervous. If your dog bites his ears frequently and is accompanied by other unusual behaviors, you should consider seeking help from a professional behavioral trainer.