Your dog will occasionally get a little itchy and will use his paws or teeth to scratch himself or rub against an object to satisfy his itch, but if you notice your dog is biting and licking his skin more than usual, you may have cause for concern.  Excessive biting and scratching at the skin can indicate potential health issues including:

The severity of your dog’s symptoms will depend on the underlying cause but generally, the symptoms are mild to moderate in all cases and the cause easily treatable.

When your dog is biting at his skin, it is usually a reaction to irritation, such as fleas or possible allergies though sometimes if your dog is suffering from a psychological reason he may bite at his skin.  

One of the most common reasons for your dog to bite and scratch at his skin is a flea infestation.  Fleas are tiny parasites that bite and feed off your dog’s blood.  A flea bite on your dog’s skin will appear as a small, raised red bump and may become larger and inflamed if your dog scratches at the area.  If left untreated, a flea infestation can lead to tapeworms if your dog ingests any infested fleas while biting at his skin.  In younger or smaller dogs, anemia can occur with heavy infestations. Sensitised individuals may also develop a flea allergy dermatitis, characterized by severe itching, constant licking and scratching, loss of hair, and scab formations.

Allergens in the environment can cause your dog to develop dermatitis, which may result as itchy, flaking skin on your dog. Allergies are a common cause of excessive biting and scratching at the skin and usually develop early in your dog’s life.  Certain breeds are also known to be more sensitive to allergens, such as Terriers, Setters, Beagles, and Retrievers.  Dogs can be allergic to a range of things including pollen, dust, dust mites, trees and certain foods.

Bacterial infections may occur in your dog if excessive scratching and biting of the skin are left untreated. A flea infestattion or allergic reaction that causes your dog to scratch at his skin may become an open wound due to scratching activity, which is then susceptible to bacterial infection.  A bacterial infection will cause your dog to further bite and scratch himself for relief and must be addressed to prevent further complications.

Sometimes foreign objects, such as glass or a burr, may become lodged in your dog’s paws or coat causing your dog to bite at the site.  A scratch from an object may also irritate your dog’s skin and cause him to bite, scratch, or lick the area. As your dog ages, he may develop arthritis, which will cause him to lick and possibly bite at his joints. Regular aches and pains should always be investigated to determine the cause and prevent additional pain in your dog.

If a medical condition is not suspected, your dog may be licking or biting at his skin for an emotional or psychological reason such as boredom, phobias, anxiety, or stress. If not addressed and corrected, excessive licking and biting of the skin can turn into an obsessive behavior.  Your veterinarian, as well as a dog trainer, can help you develop a program to train and correct this type of behavior.

Excessive biting, licking, or scratching of the skin should alert you to a potential health condition. Before making an appointment with your veterinarian, look for signs of a foreign object in your dog's paws or fur if the licking is localised.  Many times a burr or thorn may be lodged in your dog's paw or stuck in his coat.  Remove the object with care and inspect the area for any open wounds or reddening of your dog's skin.  Open wounds should be examined and treated by your veterinarian to prevent bacterial infection.   

A flea infestation is easy to spot in your dog, especially if he has a lighter coat because fleas are highly mobile parasites and that are dark in color.  Fleas also leave behind "flea dirt", which is reddish-brown fecal matter.  A flea infestation on your dog can quickly become an infestation in your home, and immediate action is necessary to treat and prevent further instances. You will want to talk to your vet to determine the best course of action, which may include prescription flea medication, over-the-counter medications, shampoo, or a combination of treatments. Following your veterinarian's strict instructions for flea control is important.  Never use your dog's medications on your cats or other animals because your dog's flea medications can reach toxic levels in cats and other small animals.  Be sure to alert your vet to the other animals in your home to get additional care and instruction for them. As up to 95% of the flea burden live off the dog and in your home, you must always treat the home adequately to prevent re-infestation.

If your dog is biting or scratching his skin due to allergies, your veterinarian will conduct a full physical examination to rule out other possible conditions before ordering allergy testing to determine potential allergens affecting your dog.  The most common form of allergy testing is an intradermal test or a "patch" test where small needles will inject an allergen just under your dog's skin.  This test is usually performed on the abdomen, which will need to be shaved.  Your vet may also order a serum test to sample your dog's blood and determine the allergen's affecting him. These tests aren't always accurate however, and can be costly.

Treatment of allergies will depend on the allergen, and though there is no cure for allergies, you can help reduce your dog's reactions over time by removing the allergen from the environment.  If your dog's reaction is food based, your veterinarian will suggest a new diet that will support your dog's health. Immunotherapy ( a series of injections) may be a possibility and can help reduce the severity of allergies.

Proper flea control can prevent excessive biting, scratching, and licking of the skin.  If you live in more humid climates and your dog plays outside you will want a preventative flea control solution that stops the fleas before they can get out of hand.  Your veterinarian can help you develop a flea control solution to prevent infestations.  

Complicated health conditions, such as dermatitis and bacterial infections can be avoided by determining the cause of your dog’s itchy skin and treating it immediately.  To prevent aches and pains resulting from foreign objects, always inspect the area your dog is biting.  Burrs and thorns can be very uncomfortable when stepped on or caught in your dog's coat.  Never attempt to remove objects such as glass or metal from your dog's body and seek immediate medical attention in these instances.  Removing the object on your own can leave behind broken pieces and possibly lead to infection. If your dog has arthritis or other joint disease, ensure they pain is well managed with ongoing medication.

Providing your dog with a safe, clean environment is important in preventing many conditions that cause your dog to be itchy.  Remove identified allergens from your home and prevent your dog from coming into contact with allergens he reacts to outside.  You may not be able to remove 100% of the allergens affecting your dog so bathing him with hypoallergenic shampoo may bring him relief and prevent itchy skin. It can help to wipe paws and belly after a walk with wet wipes and to avoid grassy areas.

Treatment cost for your dog’s excessive biting, licking, and scratching of his skin will depend on the underlying cause.  For example, the average cost for treating fleas and flea related conditions is around $350 whereas if your dog is experiencing allergy-related dermatitis, the average cost is around $1,200.