One of the most noticeable causes of dog scratching is fleas. Dog owners may see the fleas, see the flea dirt, or even get bitten by fleas themselves.

A severe flea infestation can cause hair loss and sores on the dog's skin due to scratching. Dogs may be allergic to flea saliva that can make these symptoms significantly worse.

In addition to flea saliva allergies, other types of dog allergies can cause dog scratching. Dogs can develop allergies to dog food, medication, vaccinations, or substances in their environments.

Ear mites can cause dog scratching, especially of the dog's ears. Dogs often shake their heads when they have ear mites.

Mange is a parasitic infestation that can be a cause of intense dog scratching. Causes of dog scratching from parasites can also be due to lice, ticks, and hookworms.

Hot spots are a common cause of dog itchiness. Hot spots are often triggered by an allergic reaction, infection, or poor grooming. In addition to itchiness, hot spots can cause hair loss and severe skin irritation.

Reactions to staph and staph infections of hair follicles can cause dog scratching. A skin disease called sebaceous adenitis causes damage to the sebaceous glands. Sebaceous adenitis can cause itchiness as well as hair loss.

Pelodera dermatitis and calcinosis cutis are two less common conditions that can cause dog scratching. Pelodera dermatitis is an infestation of a worm larvae that is not normally parasitic. Calcinosis cutis is a condition commonly seen in dogs with Cushing's disease that causes the mineralization of the skin.

Cancer is one of the possible causes of dog scratching. Lymphoma and epitheliotropic lymphoma can cause itchiness in dogs.

Mosquito bites and stings from bees or wasps can cause itchiness. In severe reactions to insect stings, ulcers or hives may develop. Since itchiness is a uncomfortable symptom of many different conditions, dog owners should have their dogs examined by a veterinarian for diagnosis and treatment.