What is an ear infection?
An ear infection, or otitis, is caused by inflammation within the ear. The ear canal of dogs and cats is made up of three parts: an outer ear canal, a middle ear and an inner ear. Most commonly, it is the external ear canal that becomes infected. If infections are left untreated, they can spread to the middle ear.
Healthy dog and cat ears contain low numbers of bacteria and yeast. Inflammation and damage to the tissue within the ear canal provides the perfect environment for bacteria and yeast to multiply and can lead to an infection. Infections can also be caused by mites that invade the ear.
Where do the infections come from and are they contagious?
Inflammation in the ear canal predisposing to ear infections can be due to a number of causes such as an underlying food or environmental allergy, hormonal disorder such as low thyroid hormone production, immune mediated skin disease, etc. Infections can also be secondary to something within the ear canal itself, such as a mass, foreign body (e.g. plant material), or a ball of wax.
We used to think that ear infections were simply caused by water being left within the ear canal after swimming, for instance. However, moisture within the ear will only cause an infection if inflammation is already present due to one of the above reasons. It was also once thought that “floppy ears” could cause ear infections.
We now know this is also not true because dogs with floppy ears and ears that stand up straight are both known to get ear infections.
Bacterial and yeast ear infections are not contagious to other animals or humans. However, mite infestations can be contagious to other animals within the household.
What are the clinical signs of an ear infection?
If your pet has an ear infection, you might observe some of these behaviours:
- Scratching its ear
- Shaking its head frequently
- Holding its ears down or to the side due to discomfort
- Hesitant to have the ear touched
You may also notice some of these changes:
- Ear is red and hot to the touch
- Discharge leaking from the ear
- An odour coming from the ear
Other animals within the household might smell the infected ear often or try to clean it. If the ear infection is left untreated, the ear may become thick and crusty, and the ear canal itself may narrow (stenosis). If the infection travels to the middle or inner ear, your pet may exhibit signs such as tilting of the head, problems with balance or difficulty walking.
Should my dog/cat see a veterinarian if I notice these signs?
If you suspect your pet has an ear infection, it should be seen by a veterinarian. Ear infections in dogs and cats can be very uncomfortable and sometimes painful. Pets can scratch their ears causing damage with their feet and nails. If they shake their head too much, small blood vessels in the ear may break, leading to swelling of the ear flap called a “hematoma.”
This condition may require surgery. If left untreated, ear infections can lead to a rupture of the ear drum which, in turn, can result in a deeper infection. Deep infections can cause hearing loss over time and even nerve damage.