Dogs with hanging ears have a tendency to get ear infections because the hanging ears hinder aeration and keep the inside of the ear a warm and moist breeding ground for bacteria and fungi. Certain breeds (especially pure breeds) are even more at risk because the limited gene pool weakened their immune system. My own dogs suffers ear infections each and every winter.
The infection is caused by either bacteria, fungi or ear mites. The natural reaction of the ear to the infection is to produce lots of ear wax. If this slowly dries and becomes sticky or hard, it can irritate the ear even more.
So fighting the infection must be done in 2 steps:
- Kill the cause of the infection. Since the prescribed antibiotics seem to work for a while, I assume it's the correct medicine for this infection.
- Remove the ear wax from the ear. This is done by flushing the ear with a watery ear cleaning fluid. Most of those liquids have additional antibacterial properties that hopefully prevent a new infection. You should be able to get such an ear cleaning liquid at a pharmacy, your local vet or an online shop.
In the ideal case you drip the ear cleaner into your dog's ear while massaging it in a circular motion to spread the cleaner throughout the whole ear cavity. Then you let your dog shake his head, which moves the remaining liquid as well as the ear wax out by centrifugal force. Be prepared to clean bits of earwax from the walls and ground...
In reality dogs have an instinct to keep their ears dry, so most of them really dislike flushing their ears. It helps to warm the liquid to room temperature before applying it and to consistently give your dog a really special treat after each treatment.
A little trick if your dog fights the flushing:
Soak a cotton pad with the cleaning liquid. Start stroking your dog's ear as if you were a dog licking him, then squeeze the liquid inside the ear and massage in a circular motion.
Repeat the flushing daily as long as the ear is still infected. After that, check the ear(s) regularly for signs of earwax and flush as needed. If your dog scratches his ears or rubs his head on the ground or against furniture, flush as well.