Ear infections should never be left untreated. The consequences of untreated ear infections include:
- Thickened ear canals, which may close up and lead to deafness
- Rupturing of the ear drum, another cause of hearing loss
- Ear infections that travel deep into the ear canal and can affect the brain
- Hematoma formation on the ear, from constant head-shaking
- Cuts and scrapes on the neck from scratching
- And, most importantly, lots and lots of discomfort and possibly pain for your pet.
With regard to ear infections, there are several types of organisms that can cause an infection, some of which can be really nasty. The worst of the lot is Pseudomonas, which has a lot of issues with antibiotic resistance. Most vets will take a sample from your pet's ear canal and examine it under a microscope, and then prescribe medication based on their findings. This is an important step in diagnosing ear infections, and one you that should never be skipped. If there is no sign of infection, then allergies are a more likely cause of the itchiness, and treatment will focus on that.
Keeping your pet's ears clean, especially if your dog or cat has recurring ear infections, can be very helpful with preventing re-infection. Ask your vet to demonstrate how to clean ears, and consider purchasing a good-quality ear cleaner. There are a lot of homemade remedies on the internet for ear cleaners, but these can sting and/or dry the ear excessively, so you're much better off getting something made especially for the purpose.
And for my last bit of advice - if you're sent home with ear medications for your pet, follow the directions completely! Although the itchiness may resolve after a day or two, it's really, really important that you keep giving the antibiotic and antifungal for the length of time prescribed. Some of those bacteria and yeast will still be lurking about, and if you stop your ear treatment too soon, you run the risk of the infection coming back, and even developing antibiotic-resistant strains of bacterial. Please use as directed!