Here are some of the most common causes of itchiness in dogs: 1. There are many reasons your dog may be itchy, and it can be hard to figure out the root cause of the problem. The Most Common Causes of Itchiness in Dogs When should I take my dog to the vet for itching?.What is the best anti-itch medicine for dogs?.What can I put on my dog to relieve itching?.Why is my dog so itchy but has no fleas?.15 Natural Dog Itching Remedies at Home.The Most Common Causes of Itchiness in Dogs.