My dog’s got an ear infection AGAIN…

Earache is miserable. Recurrent earache is worse.

Why do some dogs seem to have perpetual ear problems, and others never?

The answer, as usual, is rarely straightforward. The ear canal is a long tube of cartilage lined with modified skin. At the end is the ear drum (tympanic membrane), and beyond that, the middle ear bone (tympanic bulla, shaped like a cauldron).

Canal design can vary with breed – poodles’ can be super-hairy, bulldogs have canals that are narrow and scrunched-up compared to the size of the dog, and cocker spaniels have a defect in the lining of the canal that makes for recurrent infections.

The canal has resident bacteria and yeasts, similar to the skin between our toes. If the environment in the ear is upset, these normal bugs overgrow and infection results. Triggers include foreign bodies (grass seeds), ear mites, constant wetting from swimming, and overheating.

Overheating can come from a hairy ear canal, a heavy floppy ear flap (Cocker or Springer or Bassett – no ventilation), or from a canal swelling from itchiness. A hot, itchy canal will behave like the toes of an Athlete’s Foot sufferer, and management will be similar. To achieve long term resolution, management needs to address inciting causes as well as current infections – the dog equivalent of wearing cotton socks and better ventilated shoes.

For some, this may be as simple as thinning the ear flap fur.

Many recurrent ear infections are driven by skin allergies. This may be obvious if the dog also chews its feet and gets skin infections of the groin and armpits. However, if the only manifestation is twice-yearly ear infection, it can be a leap of faith to recognise it as allergic skin disease. Labradors often fit this picture. Food / pollen / mould / flea allergy can trigger the ears to itch, resulting in them becoming hot, sore, and infected.

The dog in this picture has shaken his head so hard he has burst a blood vessel in the ear flap and caused and aural haematoma. He had yeast infections, but they were not the primary problem. Itchy ear canals from allergies were causing the yeasts to overgrow. The key for these dogs is allergy management – reduction in itch will improve the frequency of infections.

Sometimes, the dog is not allergic, but has another condition such as hypothyroidism or Cushings disease, that allows infections to take root. Managing the underlying disease will improve ear health.

Every infection results in a more scarred and narrowed ear canal. Eventually, the canal ceases to function properly and really nasty bacteria move in. These can include Pseudomonas aeruginosa (can cause green slime that smells of cheese) and E coli. These bacteria eat through the ear drum and invade the middle ear. Once there, they are very hard to shift; ear drops cannot penetrate the middle ear, and give temporary relief at best. Microscopic analysis and bacterial culture are critical for the management of these dogs.

For some, the infection is so antibiotic resistant and so deep-seated that complex surgery to remove the ear canal is the only cure. It sounds awful, but can revolutionise the dog’s quality of life. A consistent post-operative comment I have had from owners is that the dog has become much more cheerful. One aggressive Belgian shepherd became completely different after having both his terribly painful ear canals removed.

Where the issue is super-hairy canals or poor lining design, a smaller operation to open the canals can be curative if performed promptly, before scarring has developed.

To further complicate matters, most ear drops contain anti-itch, antibiotic, and anti-yeast. A dog who only suffers from yeast overgrowth does not need antibiotics! Additionally, some drops contain antibiotics that should be reserved for special use, such as marbofloxacin. While convenient, repeated use of multi-chemical drops without due care leads to antibiotic resistance developing, making future infections more awkward to shift.

I am sorry to say that the dispensing of antibiotic ear drops, on demand of the owner, without first examining the ear, is irresponsible, and furthering the antibiotic resistance problem. At worst, it can be dangerous – adding ear drops to an ear that has a grass seed in it will hurt, and certain drops are toxic to the middle ear – a perforated ear drum + toxic drops is not a great combination.

If your dog’s red, painful ears are only receiving a cleaner, they need more help than this. Similarly, if you have been used to using endless bottles of multi-chemical ear drops, it’s probably worth a re-think of strategy.

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