The ear canal is the tube-like structure that connects the pinna to the eardrum. It is a part of the outer ear. Otitis externa in dogs is an inflammatory condition affecting this ear canal. It happens to be the most common ear disorder in dogs. When the lining of the ear canal is inflamed, the skin becomes red and scaly, and the dog may have itching. The ear canal may be swollen, and there may be a discharge from the ear too. In some cases, the inflammation is accompanied by severe pain.
There can be several causes for otitis externa in dogs, such as allergic reactions, the presence of foreign objects and parasitic infestations. While these can directly cause the ear canal to get inflamed, bacterial and fungal infections elsewhere in the ear can be indirect causes for otitis externa. The underlying cause of the inflammation should be identified and treated to control this disorder.
The symptoms of otitis externa include scratching of the ear and head shaking. The pinnae and the area around them may be red and sore from scratching. Some skin abnormalities and deformities such as abnormal tissue growth in the ear canal may be present. The Some breeds of dogs such as poodles and terriers, as well as long-eared retrievers and spaniels are predisposed to this inflammatory condition due to the structure of their ear canals and the pinnae.
The veterinarian may review the medical history of the dog and conduct a thorough physical examination to identify the cause. The dog may have to be sedated during the examination. An otoscope gives a better view of the ear canal, and enables the veterinarian to identify whether the inflammation is due to deep seated foreign bodies in the ear, presence of ear mites, impacted debris or because of any abnormalities or rupture of the eardrums. If the dog has pain in the ear, or if there are obstructions in the ear canal due to excess tissue growth or extra discharge, it may have to be anesthetized to reduce trauma during the otoscopic examination. Tissue samples from the ear canal can be collected with the otoscope and tested in the labs to identify the cause.
For immediate diagnosis, the veterinarian may take a smear with cotton- tipped ear buds. A dark colored discharge usually indicates a fungal infection, but bacterial infections as well as a combination of both can also give similar results. It may be an indication of the presence of ear mites in the external ear too. In that case, examining the smear under a microscope may show the ear mites, their eggs or larvae.
There are several microorganisms that normally inhabit the ear canal of dogs and other animals. While they generally do not cause any harm, a sudden increase in their numbers due to some changes in the environment inside the ear canals may cause problems. They can be identified by testing the ear discharge. A definitive diagnosis is necessary for antibiotic or anti-parasitic treatments to be effective.
Sometimes, other investigations such as testing for allergies may be needed to identify the cause of inflammation. If the inflammation is only in one ear, the possibility of the presence of tumors cannot be overruled, especially if it is a chronic obstructive inflammation. Biopsies may be recommended in such cases. X-rays may also help in locating tumors and visualizing the middle ear structures. If the dog is experiencing loss of balance, middle ear inflammations could be the underlying cause of the otitis externa.
The key to successful resolution of otitis externa is identifying the exact cause or the multiple causes of the inflammation, and eliminating them completely. Otherwise, the disorder may recur.
Treating Otitis externa
Once the underlying cause of the inflammation is identified, the veterinarian may treat the condition appropriately. The fur from all around the ear may be clipped and the hair inside the ear canal may be removed to facilitate easy cleaning. It will promote air circulation in the ear canals and help them remain dry.
Before topical application of medicines, the dog’s ears should be cleaned of any discharge or earwax. If the dog cannot tolerate the gentle cleaning process, it may have to be sedated. If the inflammation is severe and the dog has pain in the ear, cleaning the ear may have to be done under general anesthesia.
Ideally, the topically applied medication should thinly coat the lining of the ear canal. The treatment may include oral medication also, and in chronic cases, the drugs are administered by injections. More aggressive treatment may be required if the inflammation has affected the middle ear, or if infections are present.
Antibiotic therapy is required if otitis externa is due to bacterial infections. They may have to be combined with corticosteroid drugs to reduce swelling and glandular discharges, if the swelling and pain are not resolved with non-steroidal analgesics and anti-inflammatory medications. Recurrent bacterial infections may indicate another underlying cause such as an ear mite infestation. If the inflammation is found to be due to ear mites, antiparasitic drugs are used to eliminate the parasites, but if it is complicated by infections, antibiotics may be administered along with antiparasitic drugs.
The treatment of otitis externa may last for 2-4 weeks as the inflammation, as well as its cause, should be completely eliminated to avoid recurrence. The veterinarian may want to track the progress of the treatment by physical examinations every week or bi-weekly, especially in the case of bacterial and fungal infections. To resolve many chronic cases, the treatment may have to be continued for an extended period of time, while it may stretch on indefinitely in some cases. Good hygiene practices and care should complement the medical treatment to achieve best results.
Prevention of ear canal inflammation is better than treating it afterwards. Check the dog’s ear frequently for any changes such as differences in temperature, color or texture changes, an increase or decrease in the moisture content of the earwax, or any abnormal discharges. If you notice any change, the dog should be taken to the veterinarian for a thorough examination.
The proper way to clean the dog’s external ears may be demonstrated by the veterinarian. Initially, daily cleaning may be necessary, but the frequency may decrease over time to about one a week, with a maintenance check every 2-3 days. It is important to keep the dog’s ear canals dry and ventilated. If the dog swims frequently, you may need to use drying gents to eliminate excess moisture from the ear canals. When the dog is given a bath, care should be taken to prevent water from entering the ear, and if it does, it should be promptly dried. Extra moisture in the ear canal may soften the lining of the ear canal and promote fungal as well as bacterial infections. Softening of the skin reduces its capacity to act as a barrier to invading microorganisms. Keeping the pinnae as well as the ear canals dry may reduce the incidence of infections that may lead to otitis externa. In breeds that have thicker and longer hair growth in their pinnae, either by keeping the hair short with regular clipping, or removing the hair completely, may help improve ventilation and reduce the moisture content inside the ear. However, you should not attempt to remove the hair from your dog’s ears without consulting the veterinarian. Get the vet to demonstrate how to clip the fur, or to remove it by other means, and follow the instructions carefully.