Ear infections are a relatively common condition in dogs and cats and occur in all age groups. In a study drawing information from nearly 1 million dogs in the UK, 7% of dogs experienced an ear infection annually. The typical ear infection causes inflammation of the ear canal, the tube that carries sound to the eardrum. This inflammation is known as otitis externa because it affects the outer ear. Otitis media and otitis interna affect the middle and inner ear respectively. Middle and inner ear infections are much more serious conditions that can ultimately lead to neurologic signs such as a head tilt or dizziness and loss of hearing.
Otitis externa can have multiple causes, including allergies, bacteria, yeast, parasites (such as ear mites), or foreign bodies.
The immune system is the body’s defense against anything that is foreign such as bacteria, viruses, or parasites. Allergies occur when a dog or cat’s immune system overreacts to a substance that isn’t a health threat. Those substances are called allergens.
Atopic dermatitis, also known as atopy, refers to allergies to things in the environment such as dust mites, pollen, mold, trees, grass, fleas, or even another pet. The condition occurs when a pet encounters an allergen either by inhaling it or through direct contact with the skin. Direct contact with the skin explains, in part, why the feet and face can be so itchy — these are the parts of a dog or cat’s body that are most in contact with allergens. Environmental allergies may be either seasonal or year-round depending on if the allergen is seasonal like pollen or present year-round like dust mites.
Food allergies are much less common in pets than environmental allergies. When they occur, the dog tends to be allergic to common ingredients in food such as beef, chicken, milk, soy, or eggs. The foods that cats are most often allergic to include fish, beef, chicken, and milk products.
Much as they are for humans, allergies in pets are itchy, irritating, frustrating, and sometimes painful. On top of this, the itching, scratching, and licking can lead to infections.
Hot spots, also known as acute moist dermatitis, are itchy, red lesions that develop when a dog repeatedly licks or scratches at an area on his skin, creating a warm, moist wound. Hot spots most commonly develop at the base of the tail, outer thighs, neck, or face, and may seem to appear out of nowhere.