Why is My Dog Itchy?

Itchy skin is one of the most common problems seen by veterinarians. It is frustrating for owners and distressing for dogs. Itching can damage skin and can result in skin infections. One common reason for this itching is allergies and atopic dermatitis. Atopic dogs are genetically predisposed to allergic dermatitis. It is a progressive and chronically relapsing disease that causes inflammation and itchy skin. The skin barrier in affected dogs is defective and can allow allergens such as pollen, dust, and other things in the environment into the skin. The immune system reacts to these allergens and causes inflammation and itching, which results in scratching. This can lead to self trauma, skin infections, and hair loss. Over time the skin can become thickened and darker.

There are many breeds that are predisposed to atopy including Golden Retrievers, Labrador Retrievers, French Bulldogs, Shih Tzus, Lhasa Apsos, German Shepherds, West Highland White Terriers, Cairn Terriers, Scottish Terriers, and others. Many mixed breed dogs may also be affected. There are other reasons for dogs to itch, such as parasites, flea allergies, and food allergies. Some atopic dogs may be affected by these things as well, compounding the itching. Atopic dogs usually begin to have symptoms between 1 and 3 years old. In food allergic dogs, symptoms may begin under a year old or later in life. Many affected dogs live mostly indoors. There is some thought that this indoor lifestyle limits the exposure to diverse microbes early in life and may help promote allergic inflammation in humans and dogs.

Allergens are everywhere and can travel in the air for miles so it is not easy to escape exposure whether indoors or outdoors. Itching can be worse in certain seasons, but in areas where the climate is more temperate year round, the symptoms may not be as seasonal. The patterns of itching can vary but generally include foot licking, and scratching of axillary and inguinal areas, ear pinnae and sometimes ear infections, as well as under the tail and around the anus and vulva. If the lower back is itchy, this is usually due to an allergy to flea bites. Skin infections are common. These may be bacterial as well as yeast infections. The most common organisms involved are normally present on the skin, but the changes and inflammation associated with allergies allow them to overgrow. Yeast infections in particular may eventually cause thickened, pigmented skin that can have strong odors.

There is no specific test for atopic dermatitis. It is a clinical diagnosis based on history and clinical symptoms. Affected animals can be tested for allergies by blood or skin testing. Skin testing is often considered the standard; as the skin response may be directly observed. There are regional profiles based on the most common allergens in a given area. It is not possible to test for every possible allergen. Allergy immunotherapy is based on the results of allergy testing and helps to desensitize the immune system to the chosen allergens. It tries to teach the immune system not to overreact so that itching may be reduced.

Allergy immunotherapy is the only true treatment for allergies. Other treatments seek to reduce itching and help control infections. Allergy shots or sublingual drops require 6-12 months to begin working. Dogs that are allergic to many, many things may not respond as well because it is difficult to desensitize to so many allergens. Dogs that do respond may still need medications to help control itching but are generally more easily controlled than without immunotherapy. Controlling the itching is one of the main goals in the treatment of atopic allergic dermatitis. Most dogs respond well to corticosteroids such as prednisone, dexamethasone, triamcinolone, and others. While these medications work well, there are negative side effects especially with long-term use. They include increased eating, drinking and urinating as well as suppression of the immune system. Corticosteroids are very useful in helping to manage flares and acute inflammation of ear infections but may not be the best choice for long term management. Oclactinib, or Apoquel, was introduced in 2013. It is a very targeted therapy that helps reduce itching associated with allergies and atopy. It is a pill that is given to dogs 12 months or older twice daily for 14 days or until the dog is less itchy. Then it is given once daily as needed to continue to help control itching.

Cytopoint, or Lokivetmab, is a caninized monoclonal antibody that targets and neutralizes IL-31, the major inflammatory substance that is produced in an allergic dog’s skin. This injection is given by veterinary professionals every 4-8 weeks to help keep itching controlled. This may be given to dogs of any age. Cyclosporine has also been used to help control itching. It is now used more frequently in cats than dogs for itching associated with allergies. It is important to note that if skin infections are present, they must be treated along with controlling the itch. Skin infections WILL happen in allergic atopic dogs. There are other things that need to be done to help manage itchy dogs. Weekly baths help clean the skin to manage skin infections. Be sure to use dog shampoos recommended by your dog’s veterinary care team. Bathing in tepid to slightly cool water can help soothe itchy skin temporarily. Omega 3 fatty acid supplements may help disrupt the production of some inflammatory substances produced in the skin and can help support the barrier function of the skin. These are available in liquid or gel caps. Topical products such as Dermoscent Essential 6 (Dermoscent, LDCA, Bayer Animal Health), Allerderm Spot-On (Virbac SA), Atopivet Spot-On (Bioiberica SAU), and others can also help support the skin barrier.

No one treatment protocol is appropriate for all dogs all the time. It is important to understand that if what you routinely do to help keep your dog comfortable suddenly stops working, it does not mean that the current medications have stopped working. Even with a good control plan, symptoms flares and skin infections will still occur. Lapses in flea control or increased flea exposure, and for dogs with food allergies, eating something they are allergic to can greatly increase itching. Work with your veterinary care team to manage these flares and get your dog back to comfort as soon as possible.

If your dog is itchy, there are many options available to help. Talk to your vet to develop the best plan for your companion.