There are important things to know before deciding to use a medicine in a dog's ear.
You need to know if this is an infection or an ear mite problem as they are treated differently.
You can read about infections here
http://www.marvistavet.com/html/body_ear_infections.html
and ear mites here
http://www.marvistavet.com/html/body_ear_mites.html
You need to know if the ear drum is perforated or not as most over the counter meds are not safe if that is the case.
You need to know if this is something that will clear up with topical meds, require oral meds, or is related to a problem with allergies or a thyroid problem.
If you know the problem is an ear infection and that the ear drum is not perforated then there are some things you can use.
You can see if your local pet supply store carries Zymox with cortisone or find it online. I've had good luck clearing up persistent infections with that. You can read about it here http://animalpetdoctor.homestead.com/Zymox.html I would also suggest trimming the hair out of the ear so more air can circulate. Just be careful not to snip any ear while you do that. This site goes over ear infections and has another ear cleaner mentioned that had good results http://www.dermapet.com/articles/art-03.html here is just the product info http://www.dermapet.com/prod-09.html Ear infections are a common symptom of allergies in dogs. You can read about allergies and dermatitis in dogs here http://www.lbah.com/allergy.htm
Dogs can develop allergies to foods, even ones they eat all the time, and to inhaled items, and contact allergens such as rug cleaners, cedar beds, or chemicals including lawn chemicals or even flea bites.
You might want to try a different dog food that has no ingredients the same as what you feed now. Diets of Fish and Potato, venison, or rabbit etc. where the protein source is new and there are no grains in the food can work for many dogs for example. Another option is the hypoallergenic diet from your vet Hills ZD. Changing food does no good if you feed the same ingredients. Remember food changes have to include all treats and supplements. It can take 8-12 weeks or more before you see results in skin and coat.
If this is an inhalant allergy you may find using a HEPA air filter in the room the dog uses most and wiping the dog down with a damp towel when it comes in helps reduce allergen exposure.
You might want to see if some plain Benadryl helps with any itching. A common low dose is 1mg per pound of dog every 12 hours. Do check with your vet about using a med but this one or another may help him a lot. If you choose to use that please read here about cautions
http://www.petplace.com/drug-library/diphenhydramine-benadryl/page1.aspx
You may want to consult with your vet and consider doing allergy testing.
Or ask your vet about using Temaril-P to see if that works
http://www.pfizerah.com/Product_Overview.aspx?drug=TM&country=US&lang=EN&species=CN
Dogs can have low thyroid level issues and that can trigger skin and ear allergies. The vet can check for that with a blood test.
Some people find their dogs do better when they are given omega 3&6 fatty acid supplements such as Derm Caps or Linatone from the pet supply store.
If your regular vet is not able to help you then you may want to see a veterinary dermatologist and this page may help you locate one if your vet can't refer you to one
http://www.acvd.org/
Hope this helps you!
Dog Expert:Rescue, Train,Breed,Care
30+ yrs dog home vet care & nursing, rescue, behavior&training, responsible show breeding, genetics