Flea Bites

• Flea bites are a common reason for hot spots in dogs, usually due to the irritating nature of flea saliva.
  
  

Ear Shape

• According to Dog Owner's Home Veterinary Handbook, dogs with hairy, floppy ears get hot spots on the ear flaps. Golden Retrievers and Newfoundlands are prone to this kind of hot spot.
  
  

Poor Grooming or Neglect

• Dogs rescued from puppy mills or hoarders often have hot spots due to not being groomed in their lives. The ASPCA claims that poor grooming is a very common hot spot cause.
  
  

Allergies

• Allergies are common causes. These can be allergies to anything from a certain kind of food, to pollen or even the laundry detergent used in their bedding. Skin scraping tests can help identify the allergen.
  
  

Anal Gland Problems

• If the hot spots are under the dog's tail, it could be due to an impaction or infection of the anal gland. Serious cases could require surgery.