If your dog can't seem to resist rubbing, grinding and mashing his face against the furniture, the carpet and even you, the motivation could be medical or simply behavioral. This habit can indicate one of several problem's with his skin health, so seeing a vet should be the first order of business.
An allergic reaction can make your dog's face itch, motivating him to rub it on anything that gives him a bit of relief. The most common reason is seasonal allergies caused by pollens, particularly in late summer -- in dogs, this is known as canine atopy. If you've recently switched food and he develops a face rubbing habit, he may be experiencing an allergic reaction to one of the ingredients, such as wheat, chicken or artificial fillers.
Other Skin Problems
A host of other medical problems can cause the type of facial irritation that motivates a rubbing habit. Sarcoptic mange, or scabies, for example, is a skin disease that causes severe itching and inflammation. Parasites like mites also can irritate your dog's skin with extreme itching, and may lead to skin infections that make that symptom all the more severe. Your dog may simply suffer from dry skin caused by the weather. Regardless, have a veterinarian check him out.
Some breeds have facial folds that trap dirt, food crumbs, moisture and bacteria. These breeds, which include pugs, French bulldogs and English bulldogs, need to have their facial folds cleaned regularly. Otherwise, the collected particles and moisture can lead to itchy irritation and infection. Your veterinarian or groomer can recommend an over-the-counter cleaning solution for wiping out your dog's facial folds.
Your dog's reason for rubbing his face may be entirely nonmedical. Some dogs simply develop a facial rubbing habit because it feels satisfying, much like a human may rub his eyes or scratch his head. Some dogs do it as a way of leaving their scent on an object, marking their territory by rubbing their unique natural oils on something. If your vet has ruled out medical causes for this facial rubbing, consult with a trainer who can advise you on properly curbing your pet's habit.