context: Our dogs are faithful companions, and they depend on us for good care. To help your canine friend live a healthy life, you should know some of the most common health problems dogs face, their signs, and what you can do about them. Ear infections are a common canine health problem, and they can be caused by allergies, yeast, ear mites, bacteria, hair growth deep in the ear canal, and more. Symptoms your dog may have with an ear infection include: Head shaking or head tilting Ear odor Vigorous scratching Lack of balance Unusual back-and-forth eye movements Redness of the ear canal Swelling of the outer portion of the ear Brown, yellow, or bloody discharge Always take your dog to the veterinarian if you think he has an ear infection. In most cases, cleaning and medicating the ear canal will quickly clear up an infection. However, surgery can be needed for chronic infections or if forceful head shaking results in the rupture of a vessel within the outer part of the ear. Read more about ear infections in dogs. Tapeworms, roundworms, hookworms, and whipworms are common internal parasites in dogs. And although any worm infestation can make your pooch uncomfortable, some, like hookworms, can be fatal in puppies. Signs your dog may have worms include: Diarrhea (may be bloody) Weight loss A change in appetite A rough, dry coat Scooting on his bottom Vomiting (with roundworms in particular) An overall poor appearance The best way to diagnose a worm problem is with a visit to the vet. Treatment depends on which type of worm your dog has, but generally includes an oral medication and may require follow-up. Don't try treating worms yourself: A medication that kills roundworms, for example, doesn't kill tapeworms. Read more about worms in dogs. It takes just three weeks for one flea to turn into an infestation of 1,000 biting bugs. A very common canine health problem, fleas are easy for your dog to pick up, but they're also easy to treat. Signs your dog may have fleas include: Excessive scratching, licking, or biting at the skin Hair loss Hot spots Allergic dermatitis (allergic response caused by contact) Tapeworms (which are carried by fleas) Flea dirt (looks like small black dots) against your dog's skin Untreated, fleas not only make your dog intensely uncomfortable, they can also cause allergic reactions, infections, and even lead to anemia from blood loss. Talk to your vet about the right flea medicine for your dog, which may include collars, oral medicine, shampoos, sprays, or topical liquids. Read more about flea control and prevention in dogs. They’re commonly known as hot spots, but the medical term for those bare, inflamed, red areas you often see on dogs is acute moist dermatitis -- a bacterial skin infection. Anything that irritates your dog's skin enough to make him scratch or chew can lead to the pain and itch of hot spots, which, if left untreated, can quickly grow larger. A hot spot's location can help your vet diagnose its cause. Fleas, for example, may be the source of a hip hot spot, while a hot spot at the ear might point to ear problems. Treating hot spots may involve shaving and cleaning the irritated area, antibiotics, anti-inflammatory drugs ( NSAIDS), steroids, or topical medications, depending on how bad the hot spots are, and how much pain your pooch is in. Read more about hot spots in dogs. Vomiting is a common dog health problem, with dozens of possible causes, from infection or intestinal parasites to pancreatitis, kidney failure, heatstroke, an obstructuion in the stomach or intestine, or poisoning. Symptoms are basic: abdominal heaving and drooling caused by nausea. If your dog also has diarrhea, blood in the vomit, seems lethargic, continues vomiting, or can't hold down liquids, contact your vet right away to prevent life-threatening dehydration. Treatment depends on what's causing a dog's distress, and may include fluid therapy, drugs to control vomiting, and homemade foods like well-cooked skinless chicken, boiled potatoes, and rice. Read more about vomiting in dogs. Diarrhea in dogs, as with vomiting, can have lots of causes, including stress, infections like parvo virus, intestinal parasites, and food problems. Diarrhea symptoms are pretty obvious -- look for loose, watery, or liquid stool. Because diarrhea can easily lead to dehydration, be sure your dog has plenty of clean water available, then take your pooch to the vet if the diarrhea persists for more than a day, or immediately if there's also fever, lethargy, vomiting, dark or bloody stools, or loss of appetite. Read more about diarrhea causes and treatments in dogs.