Your dog most likely has ringworm. Sorry.
I don't know how you mean losing hair, if sheding is what your talking about, I'm not sure if the hamster might be sick or not, but if it is coming out in clumps and/or leaving red patches or irritated skin then I'd take Mr. Hamster directly to a vet. ASAP It could be something simple but I've found from my own experience, if someting is moving quickly with your animal, you need to move quickly.
If your female dog's nipples are turning black and she has black patches on her skin, this may be normal for her specific breed. If it is not, she may have Black Skin Disease, also known as Alopecia X.
Cows are mammals. All mammals have a body covering of skin, fur or hair. In the cow's case, the body covering is skin and hair.
Melanin is responsible for the colour of our hair and skin. Albino's have no melanin therefore they have no colour anywhere on their bodies. Their skin appears very pale and their hair is extra light blonde.
Pigs have tough skin as a covering. The skin is naturally dry, but has soft areas under their legs, in their ears and on their bellies.
I have vertiligo and it can effect your hair, in my experience my hair goes completely white in patches it is a very similar to the white patches you may get on your skin.
Tumors and mutations of the skin including discolored skin, patches of no hair, and different textures.
If a dog (any dog) is losing hair in big enough patches to see his bare skin where he has lost it, he probably has mange, and should be seen by a vet. There are other causes too,but mange is the first thing the vet will suspect. Take him to the vet.
It could be psoriasis, another sign of it is little dimples in one fingernails.
a fungal skin infection
Yes
White patches of skin, Itchyness, and depression.
This mouse may have skin parasites such as fleas or mange.
It could be that the dog has sensitive or itchy skin and therefore is biting or scratching at the skin so that there are patches of skin missing.
Not if you have huge patches of skin on the arms. If you have Huge patches on the legs or small patches on the arm they could.
The proper term is psoriasis. Psoriasis is a skin condition where the skin cells grow too fast and build up causing large white, scale like patches.
Vitiligo