Do dogs badly affect the condition of a child with asthma?

If Allergic-Sure. Allergies are a major trigger of asthma. If your child is allergic to the dog, you are asking for trouble!
Maybe. If a child with asthma has a frequent pet exposure or experiences symptoms around an animal, allergy testing by blood work (rast) or by skin testing can confirm a suspected allergy. Indoor animal avoidance is often needed for severly allergic asthma patients. Alternatively, allergy shots may make living with an animal possible.