• Microorganisms (bacteria, yeast)
• Allergic dermatitis
• Parasites (ear mites, ticks, mange) and
• Foreign bodies (ticks, grass awns, dried medication, dried wax, displaced hairs)

Microorganisms and skin allergies are amongst the most common direct causes of otitis externa.

Predisposing factors include the ear structure (long floppy like with Bassets, hairy ears or long narrow ear canals), wet, moist ears and diseases that obstruct the ear canal (growths, swelling of the ear canal tissue). Dogs that swim a lot (Spaniels, Labradors etc.) and those that are bathed frequently (Poodles, Yorkies etc.) are over presented, but any dog or cat can get this condition.

Symptoms of external ear infections include rubbing and scratching, reddening of the skin, hair loss and swelling of the affected ear(s). In many cases a distinctive bad odour is also evident especially when microorganisms are involved. Sometimes the condition is so bad that dogs refuse to eat and/or sleep at night.

Dogs and sometimes cats can also present with what is called an othaematoma, where one or both of the ear pinna(e) are swollen due to the buildup of blood under the skin as result of excessive shaking of the head.

When the otitis externa is severe infections might spread to the middle and inner ear structures causing symptoms such as a head tilt, walking in circles, shaking of the head, often inappetence and show reluctance to be touched around the affected ear(s). Although rubbing, scratching and sensitivity is often the only signs, middle ear infections are very painful. Inner ear infections, where the vestibulocochlear area of the brain is involved, are mainly seen by a head tilt, balance problems, a one sided droopy face and walking in circles.

When skin allergies are involved other areas such as the face, feet, armpits, belly and/or the area un-der the tail are also itchy. This will be seen by scratching, rubbing, chewing, redness and hair loss of the affected areas.

At Vet Hospital a full treatment plan will be discussed during the consultation of ear infections. One or more follow-up examinations will also be strongly recommended.

Diagnostic Tests

Many factors may come together in the development of your pet’s ear problem. Recognition and subsequent treatment of all factors are the keys to successful clinical management of the otitis externa. With any ear condition, it is important for consult an experienced veterinarian as soon as possible. Because there are many causative agents and the treatment differs for all these conditions it is always recommended to know what to treat for. Depending on many factors your family veterinarian will very likely recommend a basic ear smear for evaluation under a microscope and an otoscopic evaluation. Other tests might include bacterial cultures and an antibiogram (to determine the best antibiotic for specific bacteria present) and even head X-rays.

Common Conditions & Treatment

Microorganisms that overgrow in the ears are commonly yeast infections (Malassezia), Coccal infections, mixed bacterial infections and occasionally Pseudomonas infections. The last three conditions are all bacterial infections. A combination of these organisms can also be present. Microorganisms (severity, quantity and type) are diagnosed on an ear smear. These infections can be primary or as a result of any of the other causative agents. They are treated with specific scheduled antibiotics and proper cleaning of the ear. In mild to moderate cases one can often treat at home, but moderate to severe cases need professional cleaning under anaesthesia.

Pseudomonas infections are known to be very stubborn and difficult to treat and an aggressive, long term treatment protocol with regular follow-up examinations are indicated in these cases.

Allergic dermatitis or skin allergies are the result of environmental proteins, also called allergens, (commonly flea saliva [majority of cases], grass, pollens, certain food proteins but many, many more exist). Skin allergies are very often diagnosed on exclusion of similar looking conditions and a high index of suspicion. A strategic flea control program will always be recommended as even if flea saliva is not the main cause for the allergy it only takes one flea to make other allergies worse. Trial medication and/or diet exclusions can also be requested in atypical cases.

An allergy is a developmental condition. The more an animal is exposed to a certain allergen, the more likely the animal is to develop an allergic reaction to it. Allergies can be due to the sum total of a combination of allergens or it can be due to a single source. The best way to treat allergies is by re-moving the causative allergen(s), but because they are often unknown or in some cases it is difficult to do so, immunosuppressive, essential fatty acids and antihistamines are used. Allergies can also show a seasonal prevalence. In addition to ear treatment, prescription corticosteroids or cyclosporines are used for the control and maintenance of severe, stubborn and/or unknown allergies.

Food allergies are diagnosed through hypoallergenic novel diet trial, where a specific prescription diet such as Eukanuba Dermatosis (potato & fish proteins), Hill’s Sensitive skin (chicken proteins), Hill’s Z/D (hydrolysed chicken proteins) or Vet’s Choice Sensitive (duck & rice proteins) is fed for a period. The theory of a novel diet is to feed a type of protein that the animal was not or less likely to be ex-posed to during its lifetime. The principle is that animals are less likely allergic to for example potato proteins than beef or sheep proteins.

Complete resolution of skin allergies is very important in the management of long term external ear infections.

Ear Parasites include Ear mites (Otodectes cyanotis), ticks and mange (Demodex spp.). These conditions are diagnosed on ear smears, skin scrapings and/or otoscopic evaluation of the ear. Because each of these parasite groups is treated with a different anti-parasitic medication it is once again important to consult your family veterinarian for advice.

Foreign bodies are anything that is stuck in the ear canal that does not belong there. When a foreign body is suspected the attending veterinarian will recommend a quick otoscopic examination. This examination might need some degree of sedation in order to minimise discomfort to your pet. Removal under sedation is the treatment of choice.

Growths including polyps and cancers that obstruct the ear canal(s) compromising the opening and the skin of the outer ear. Removal under general anaesthesia, if possible is the treatment of choice.