The term "affected dogs" refers to canines that have been diagnosed with a specific medical condition or disease. This could be due to genetic factors, environmental influences, or other underlying causes. When veterinarians use this phrase, they are indicating that the dog in question has exhibited symptoms of illness and has undergone testing to confirm the presence of the condition. The term can also refer to dogs that have been exposed to a contagious disease but may not necessarily be showing any signs of sickness themselves.