Mange

Mange is caused by parasitic mites that live on or near your dog's hair follicles. It can be passed from dog to dog.

Allergies

Dogs can have allergies, just like people. If your dog comes in contact with an irritant such as a new cleaning chemical or perfume, she could have an allergic reaction to it.

Symptoms

Symptoms of mange include your dog losing hair in patches, especially around her eye, ears and feet. She could have scabs or sores on her skin. If your dog is having an allergic reaction localized around her eye, she could scratch and rub at the skin until she has pulled all the hair away.

Treatment

If your dog is losing hair around her eye because of mange, insecticidal washes and medication will kill the mites. If your dog is scratching at her eye because of allergies, removing the allergen from her environment will stop the scratching.

Time Frame

Once you begin treating your dog for mange, it will take about a month to eradicate the mites. After the mites are gone, her hair will start to grow again. If your dog was scratching away the hair around her eye because of an allergic reaction, hair growth will begin as soon as the allergen is eliminated.

Source:

University of Tennessee College of Veterinary Medicine: Hair Loss in Dogs

"What Your Dog Is Trying to Tell You"; John M. Simon, Stephanie Pedersen; 2000

ASPCA: Mange