One of the most common skin diseases that develop in dogs is atopic dermatitis. Most of these cases are caused by allergies to substances in the environment. Dog owners are aware of the possibility that their dogs may have environmental allergies to plant pollen and dust or dust mites, but may be completely unaware of one more very significant environmental allergen that can cause ill effect on susceptible dogs: mold.

Symptoms of mold allergies in dogs:

Dogs allergic to mold typically develop a year-round skin problem. If they are allergic to mold, the symptoms may wax and wane with atmospheric humidity (which allows molds to reproduce at a faster rate) but will be present to some extent year-round, because the offending allergen is present all the time, not just seasonally like some pollens. This allergy is most likely to develop in dogs between the ages of 6 months and 3 years, however, dogs can develop an allergy at any time during their lifetime.

Mold allergies tend to manifest as a skin condition. Symptoms may include scratching (often persistent), inflamed and irritated skin; dry scaly skin, localized or generalized hair loss, chewing/licking (especially the paws); chronic ear infections. It is also possible, but uncommon, for molds to cause respiratory symptoms such as coughing, sneezing, wheezing, labored breathing, discharge from nose and/or eyes, and even loss of appetite and lethargy in more severe cases. Dogs with mold allergies are also frequently affected by other inhalant allergens, such as mites.

More information: https://www.whole-dog-journal.com/product/encyclopedia-of-natural-pet-care/