A dog that keeps sneezing may be caused by a variety of reasons. Some common reasons include:

Environmental stimuli: such as dust, pollen, smoke, etc., may cause irritation Dog's nasal cavity.

Allergies: Allergies to food, pollen, dust mites and other substances.

Foreign bodies in the nasal cavity: such as dust, hair or other small objects.

Infections: such as colds, nasal infections, etc.

Structure problems with the nasal cavity: such as nasal stenosis or deformity.

Dental problems: Toothache or oral infection may spread to the nasal cavity.

Irritating odors: Perfume, disinfectant and other odors may trigger sneezing.