Causes for bald spots on dogs vary from allergies, infections, pressure sores, rashes and hives. Other reasons can be foreign body reactions such as glass, post-clipping alopecia as well as Cushing's disease. Genetics can also cause bald spots, according to WebMD.
Dog breeds that genetically develop bald spots are whippets, dachshunds, Italian greyhounds and Chihuahuas, reports WebMD. These specific breeds are prone to bald spots on the chest, thighs, back and outer ear. Infections from glass, thorns or even a dog's coarse hair can cause bald spots to appear. Infestations caused by fleas can lead to bald spots when the dog licks and bites the infected areas. Dog breeds such as the Alaskan malamute, Siberian husky and Keeshond can experience bald spots as a side effect of clipping.
Pressure sores, often found in older dogs, also leave bald spots, explains WebMD. Older dogs are prone to pressure sores on their elbows or other bony parts of their body. This occurs when they are in regular contact with hard surfaces. Over an extended period, the constant pressure thickens the skin, causing the hair to fall out and calluses to form. It is recommended to seek a veterinarian's advice when balding spots are accompanied with itching, a bad odor, irritated or infected skin, and behavior changes.