I have been asked about ear infections in cavaliers.  Antibiotic ear drops from your vet will help, but these can recur and in some dogs can be a problem.  Trimming the fur on the inside of the ears can help, as can plucking the fur from the inside of the ear canal, but do this carefully as if they have a sore ear, it will be more painful, and even the best pet may snap.  This will enable the air to circulate around the ear, discouraging infection. Be aware also, that grass seeds can work their way inside a dogs ear, and will need veterinary action to remove it.  These can set up irritation and be very painful for the dog.  If your dog is shaking his head, whining and pawing at his ears, or constantly scratching or rubbing his ears, seek medical help immediately.

…  Anne