Could be from a number of reasons such as severe flea infestation, bad grooming, mange, etc. Best bet is to take it to the vet to get a skin scrape done in case it is mite mange which is spreadable to other canines and will progressively get worse.
Your dog has bald spots because it may suffer from stress or a disease or maybe it has just come from old age.
It could be a sing of mange.
My dog had this, and the vet referred to them as hot spots. I simple shaved the area around the bald spot so that no hair was rubbing against the area. I then gave the dog some Benadryl. After a few weeks, it was all gone. This would occur ever spring. I learned of this method, after a $200 visit to the vet. Cheers
Bald spots are the result of the cessation of hair growth. Therefore, a bald spot cannot be grown, but rather not grown.
There are some things you can do to help get rid of bald spots. This includes wearing a wig, changing your shampoo, changing your diet, and use hair loss treatments.
Children should not have bald spots, unless you had a head injury that damaged the scalp. If you are concerned about a hairless area, talk to your doctor.
He is going bald, and the hat covers the bald spots
true
Hair Loss, Bald Spots, Acne, Loss of Limbs
Guinea pigs all have a bald spot behind each ear, this is normal. If they have any bald spots other places then they probably have some kind of mites or fungus, and you should take them to the vet right away. good luck and i hope this helped!
Selective breeding is where, say you want a really spotty dog, you would breed a female dog with lots of spots with a male dog with lots of spots. Their offspring would have more spots than a normal dog of that breed, then the offspring with the most spots are bred together. This carries on until you get a dog with the right amount of spots that you want.
If your dog is not yellow it is brown with spots
Sometimes when hamsters are stressed they rip their fur off.
http://www.boxerforums.com/losing-patches-of-fur-t19467.html