Dogs get ear infections primarily due to factors that create a favorable environment for the overgrowth of bacteria or yeast in their ears. Their ear canals are more vertical and L-shaped compared to humans, which can easily trap moisture, debris, and microorganisms, leading to infections. Common causes include allergies (both environmental and food-related), hypothyroidism, excess moisture (especially from swimming), foreign bodies like grass or sand, parasites (such as ear mites), hormonal imbalances, and breed predisposition (especially dogs with long, floppy ears or excess hair in the ear canal). Infections most often involve bacteria like Staphylococcus and yeast such as Malassezia. Excessive cleaning or trauma can also contribute to infections by irritating the ear canal and disrupting the protective barrier. Ear infections can be very painful and cause symptoms like head shaking, scratching, swelling, discharge, odor, and sometimes more severe neurological issues if the infection spreads deeper.