Sometimes the medication is ineffective because it is not the proper medication for the cause of the problem. This is why diagnostic testing is so important.
In many cases the ears are not completely clean when medication is applied. Even if a small amount of bio film is left in the ear an infection can survive and recur.
Most ear medication is contained in non-transparent bottles in order to protect the contents from light exposure. It can be difficult to tell when the bottle is empty so it is not uncommon for pet owners to think they have applied medication when the bottle is actually empty.
It is important to apply ear medication to the right place in the ear. Often times the right place is deep into the ear canal. Many owners are afraid of hurting their pet and so they do not insert the tip of the applicator far enough into the ear to get the medication to the right place. Some pets have very long ear canals, making this process even more of a challenge.
Family communication can be an issue. We have found that sometimes one family member thinks another family member is medicating the pet’s ears when they are not. This inconsistent treatment does not help to eliminate the infection.
Treatment length can be an issue. When the treatment course is not long enough, or if it is cut short by the owner, the medication will be less effective.