Dermvet Skin & Ear Clinic

The ear canals are an extension of the skin and are often affected when there is a generalised skin disease, but in several instances, the ears are the only part of the skin affected  (e.g. ear mites and   in 5-10% of cases of canine atopy).   Inflammation of the external ear canal is referred to as otitis externa .

Primary causes of otitis  include  parasites such as ear mites (Otodectes cynotis ) scabies mites (Sarcoptes scabiei) and rarely Demodex canis mites,  allergic skin diseases such as atopy and food allergy,  hormonal diseases such as hypothyroidism, keratinization disorders   (diseases which alter the normal production of the stratum corneum and hair), tumours and  foreign bodies such as grass seeds and less commonly autoimmune diseases such as pemphigus .

Predisposing  factors , which do not directly cause otitis, but make it easier to develop include excessively waxy ears,   hairy ear canals, conformational features  e.g.  pendulous ears more predisposed that erect ears  due to increased humidity  in ear canal -likewise excessive moisture from swimming.   In certain breeds such as Sharpeis, the conformation is such that the ear canal is naturally very narrow (stenotic)  with a tight ear flap which increases humidity and prevents natural clearing of wax.  Sharpeis also are commonly affected with the primary cause of otitis,  atopy.  Obstruction of the ear canal by polyps and or  untreated aural haematomas affecting the whole ear flap can also predispose to otitis.

Perpetuating factors include bacterial  infections with Staphylococcus pseudintermedius,  Proteus or Pseudomonas species and infections with the yeast Malassezia pachydermatits and the pathological changes induced by the primary otitis if they are not dealt with adequately-  stenosis of the ear canal and glandular  hyperplasia as a results of chronic inflammation.  Two  overlooked perpetuating causes are the  failure to  clear the horizontal ear canal of debris adequately and the development of  middle ear disease- otitis media.

When presented with a case of otitis,  I will usually take samples from the affected ear to examine under the microscope.  This is a very important part of the work up of a case as it allows me to identify what parasites and  microorgansisms are involved with the process and it what numbers.    If rod shaped bacteria are found, this could indicate pseudomonas and I will then have to take swabs for  bacteriology and antibiotic sensitivity as this organism is often resistant to many antibiotics and it can do a great deal of damage to an ear.

If I cannot visualise the ear drum after cleaning the ear canal in the consulting room, I will advise either sedation or general anaesthesia to clean it.  This is important for several reasons – one important one being that all the licensed veterinary ear drops  are contra-indicated if the ear drum is ruptured and the other being that failure to remove debris from the bottom of the ear canal can prevent successful resolution of the otitis.  Usually a general anaesthetic  is neccessary as sedation is not enough to prevent the animal from feeling considerable pain when they have their inflammed ears cleaned.

I use a Storz Video Otoscope to clean ears when under anaesthetic. This instrument allows me to see the ear canal in extremely  great detail (impossible with a hand held otoscope) and examine the ear drum for evidence of perforation.  A channel in the otoscope allows me to pass down either  grasping forceps to remove debris and foreign bodies or  flushing tubes and flexible curettes  to clean the horizontal canal and the middle ear if the ear drum is ruptured.  The success rate of medical treatment of dog ear infection has improved considerably after purchasing this equipment.   I show clients the videos of their  pet’s ear flushing procedure and can give them a copy on a CD to take home if they wish!

It is not unusual for an animal to have a flushing procedure performed more than once- this is necessary to keep debris out of the ear, to allow medications to work and to prevent relapses. This is particularly so in cases of pseudomonas ear infections  complicated by middle ear disease -some cases have had to be flushed on as many as 8 occasions before the otitis has resolved and the ear drums healed.

As in all skin cases,  a thorough work will be done in each case to ascertain the primary cause of the otitis  and treatment will involve the use of topical and systemic medications appropriate for the individual case.

Total Ear Canal Ablation/Bulla Osteotomy

In some cases, the chronic pathological changes to the  ear canal are so severe that medical treatment  is not possible.  These “end -stage ears” are a source of great discomfort for an animal (dogs usually) and although are  usually associated with signs of pain such as headshaking and ear scratching sometimes  present as a dog becoming withdrawn and this is missed by owners who think their pet is just  ”getting old” or the deterioration of the dogs demeanour has occurred over  a such a long period that the owners fail to see it.

Surgery to completely remove a chronically diseased ear canal  -Total Ear Canal Ablation and Bulla Osteotomy  (TECA-BO) – can really transform the lives of these cases.   I have carried out this operation in over 180 cases over the last 18 years with a very high success rate.  Owners often ask if the animal will be rendered deaf after this surgery – the answer is no.  They may be “hard of hearing” ( usually no worse than they were with their diseased ear canals) but not deaf and will respond to people if they talk a bit louder than normal.