Mites, ringworm fungus & bacterial infections can cause bald patches, irritation & hair loss in dogs. Vet treatment is required.
Skin Infections
Food or environmental allergies in dogs commonly cause hair loss, skin irritation, redness, itching & secondary infections.
Allergies
Overactive adrenal glands (Cushing's) or underactive thyroids (hypothyroidism) affect hair growth cycles in dogs.
Endocrine Diseases
Stress in dogs increases cortisol leading to alopecia & fur loss. Calming training, routine & supplements help.
Stress & Anxiety
Dogs naturally lose more fur during seasonal shedding periods in spring & fall which is normal. Excessive shedding needs vet exam.
Shedding Seasons
Some dogs like Poodles have breeding making them prone to pattern baldness or follicular dysplasia despite good health.
Breed-Related Fur Loss
Lack of nutrients like proteins, fatty acids, zinc or vitamins can cause dry, brittle and thinning fur in dogs.
Nutritional Deficiencies