Itchy dogs may scratch, lick, or chew at themselves excessively, rub against furniture or the ground, or shake off frequently.
There are many potential causes of itching in dogs. Any dog with severe itchiness should be evaluated by a veterinarian, especially if skin lesions develop.
A Matter of Fleas
Fleas are small, brown, jumping insects that inhabit a dog’s skin and feed on its blood. In addition to the itching caused by a flea bite, some dogs are also allergic to flea saliva, which causes especially severe itchiness.
Fleas can be seen with the naked eye; using a flea comb can help to find live fleas or flea dirt (flea poop) in a dog’s fur.
Flea dirt is digested blood that looks like black debris and reveals red streaks when rubbed onto a damp paper towel. Other signs of fleas include skin redness and hair loss, especially on a dog’s back toward the base of the tail.
Fleas may be a persistent problem since they can last up to 4 months in the home.
The best way to prevent fleas is to keep your dog on year-round flea prevention. Many types of preventatives are available, including collars, topical solutions, and oral tablets, but some products work better than others.
Talk to your veterinarian about which option would be best for your dog. If your dog already has fleas, you should administer flea prevention ASAP and keep your dog up to date for at least 6 months.
Atopy, Environmental Allergies
Like humans, dogs can be allergic to environmental particles such as dust, mold, and pollen. Environmental allergies in dogs are called atopy. This is a condition that a dog inherits from its parents.
Atopy in dogs often manifests as excessive itchiness, usually around the face, paws, underarms, or groin. It can cause hair loss with red, thickened underlying skin.
Symptoms may arise only at certain times of the year or may be present year-round, depending on what the dog is allergic to.
Dermatologists can perform intradermal allergy testing to determine what a dog is allergic to, but most often atopy is diagnosed based on symptoms.
Treatment involves managing the itchiness and minimizing allergen exposure. Wiping the paws after walks and regular bathing can help to remove allergens, but you should not bathe your dog more frequently than once every 2 weeks unless directed by a veterinarian, as this can cause dry skin.
Fish oil supplements containing omega-3 fatty acids help to improve skin health; these may benefit dogs with atopy. Dogs with severe atopy may require year-round medical treatment for good control.
Presence of Food Allergies
Dogs can also be allergic to food ingredients. Most often, dogs with food allergies are allergic to a protein component, including dairy products, beef, lamb, chicken, soy, or gluten.
Food allergies often cause year-round itchiness, and may be associated with frequent ear infections or digestive issues.
Food allergies are diagnosed through an elimination trial, in which certain ingredients are removed from a dog’s diet to assess the response.
For example, a dog whose normal food contains beef may instead be fed a fish-based diet. If the dog’s symptoms improve once a specific component is eliminated, then there is a good possibility of an allergy to that ingredient.
Some owners may elect to try a prescription hydrolyzed protein diet; these hypothetically eliminate all ingredients that may be causing an allergy. If a dog responds well to a certain diet, it may be recommended that they continue eating this for life.
Dealing With Contact Dermatitis
Contact dermatitis occurs when a dog’s skin touches something that causes an allergic reaction. Potential causes include pesticides or other chemicals, materials like wool, and grasses, but contact dermatitis can be initiated by essentially anything.
Symptoms include significant itchiness, skin redness, and possible hives, usually in the area where the contact occurred.
Contact dermatitis is treated by identifying the offending substance and preventing the dog’s exposure to it.
A Matter of Mites
Dogs can have two types of skin mites: Sarcoptes and Demodex.
Demodex mites are normal inhabitants of the hair follicles and are not usually problematic, but their population can overgrow in young puppies and sick or elderly dogs. Demodex overgrowth may cause hair loss, but does not usually cause significant itchiness.
Sarcoptes mites, on the other hand, cause excessive itchiness. These are contracted from other dogs or wildlife like foxes. Mite movement and burrowing into the skin causes severe itchiness, as well as hair loss and red, crusty skin often starting on the edges of the ears, legs, or underbelly and possibly extending to the entire body if not treated.
Sarcoptes mites can be temporarily transmitted to humans and cause skin irritation. Many medications, including some brands of flea/tick preventatives and heartworm preventatives, are effective against mites. Please consult with a veterinarian before administering any medications.
Presence of Skin infections
Skin infections occur once the skin is already inflamed or damaged, often secondary to underlying skin allergies. Healthy skin has an outer barrier that protects it from infection; when this barrier is compromised, bacteria and yeast can enter into the superficial or deep skin layers and cause infection.
Skin infections cause significant itchiness in dogs, as well as red, raw, bad-smelling skin with hair loss.
Yeast infections are often associated with a dark brown discharge on the skin surface, while there may be pus on the skin surface with bacterial infections.
Skin infections must be treated as appropriate with medicated shampoos, ointments, or oral antibiotics to resolve the associated itchiness.
Behavioral Disorders at Play
Anxiety, stress, and compulsive behaviors can cause excessive licking and chewing in dogs. However, behavioral disorders are usually diagnoses of exclusion, meaning that medical causes like those described above must be ruled out first.
If your dog is diagnosed with a behavioral disorder, working with a dog trainer may be helpful to increase daily enrichment and redirect unwanted behaviors in a positive way.
If behavioral modification through training is not sufficient, you may also speak with a veterinarian to determine whether medication is an appropriate next step.