Because ear infections are common in dogs and cats of all ages, breeds, and environments, it is important to be aware of the causal factors. The ear canal is divided into three sections, externa – external canal, media – middle canal, and interna – internal canal. Otitis means inflammation of the ear. The root term Otic refers to the ear, while –itis indicates inflammation. Combined, as Otitis externa, the term indicates inflammation of the external ear. Some factors may cause infections in all three parts of the ear canal, while others tend to stick to one or two areas.
Ear Mites, fleas, and ticks
The most common cause of infected ears in pups and kittens is ear mites. It is very common for them to contract the ear mites from their mother during initial bonding stages of nursing and care. At first, the mites may be invisible to the naked eye, but after a few months, the mites can be spotted by their discharge, very small dots, brownish in color. Ear mites irritate the skin lining of the ear canal, and can cause the skin to thicken, decreasing the canal diameter, and possibly increasing the likelihood for foreign particles to become trapped.
There are four main kinds of infecting ear mites, Otodectes, Notoedres, Sarcoptic mange and Demodex. Otodectes and Notoedres are both tiny, and spider-like, and they live in or on the skin, typically around the media canal. Demodex and Sarcoptic Mange mites, however, cause infection of the external flap of the ear, avoiding the ear canal. These mites bite and burrow into the skin, causing intense skin irritation and inflammation.
Fleas and ticks are similar to ear mites, in that they can infect the media canal and the external ear flap, by biting and living as parasites on the dog or cat. Fleas carry bacteria that can infect an abrasion caused by the animal scratching the irritating bite, while ticks attach to the animal, and can pass bacteria directly to the blood. Ticks and fleas can cause allergic reactions, inflaming the skin around the bites, causing the ear canals to become blocked.
It is common that the environment of the dog or cat can influence whether the animal is prone to ear infections. Extreme heat can lead to infection, by providing the perfect grounds for bacteria or yeast to grow rampantly. Both bacteria and yeast respond to increased temperature with rapid growth. Foreign particles from the environment, such as plant particles, dirt, or water can cause irritation to all parts of the ear canal if deep enough. The animal’s body responds to the foreign object by swelling, which can create blockage, and hearing loss, while also possibly becoming infected from scratching. Allergies can be a factor in whether the animal is prone to ear infections. If a particle comes into contact with the ear canal, and the animal is allergic, the particle may cause the skin to become inflamed and infected.
Fungus and Yeast
If yeast or fungus particles make it into the ear canal, they can thrive and grow. The dark, moist, and warm area creates an ideal environment for growth. The growth of yeast or fungus results in a clogged, itchy ear canal, which then can become inflamed and infected from scratching or irritation. Yeast infections and fungal infections are more commonly found in cats than dogs.
Skin cells, Wax or Hair Build-up, and Abrasion
Skin cells, wax, and hair can fall into the ear canal, causing a build-up to occur. This forms a sort of plug, which can contain bacteria or fungus. If the skin around the build-up becomes inflamed from the blockage, the ear can become infected. The animal can feel the blockage and often will scratch the ear rapidly. This abrasive reaction to the annoying feeling in the ear can result in broken skin on the external canal, which can easily become infected if bacteria from nails enter the broken skin.
Cancer or Tumor
Sometimes an infection of the ear can be caused by malignant or benign tumors in the canal. The blockage they cause may cause irritation to the skin, which causes the animal to scratch. The area can become infected from the bacteria in the nails.
This information is for informational purposes only and is not meant as a substitute for the professional advice of, or diagnosis or treatment by, your veterinarian with respect to your pet. It has, however, been verified by a licensed veterinarian for accuracy.