Why Does My Dog Lose Massive Amounts Of Hair I Mean Bald Spots?

Hair loss can occur with several different problems.  Dermal parasites like mites or ringworm are common causes of hair loss.  Pyoderma (skin infections) can also cause hair loss and prevent hair regrowth.  Self-trauma is a common cause of hair loss--this is usually secondary to itching.  Itching can be due to flea allergy, environmental allergy, and hot spots.  
Certain endocrine (hormonal diseases) like hypothyroidism and Cushing's disease can cause hair loss.
Your veterinarian will want to run diagnostics--skin scrape (to check for mites), fungal culture (to check for ringworm), and an impression smear (to screen for yeast or bacterial infections).  If endocrine diseases are suspected blood work will need to be run.
Treatment will be both symptomatic and aimed at treating the underlying medical condition.

It's quite natural in hairy dogs during season change.....or if your dog lies always n wet places it can occur....dis skin disease during season change will automatically curd...no problem....orelse .. Get skin ointment for your pet.......................it's common for German sheperds