The article discusses refractive errors in dogs. The refractive errors presented in the article are myopia, hyperopia, anisometropia and astygmatism. These disadvantages are discussed in individual dogs breeds. Analysis has proved that most of dogs are emmetropic an thus have normal visual acuity. In dogs and human alike the refraction defect may have a genetic compound, it may be congenital or acquired and may change with age. Ametropia directly affects the orientation of animals and their behavior, therefore examination for refractive error is an important element of vision testing.