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Lick, Bite, Chew, Scratch. Why is my dog so itchy!
Could your dog be suffering from skin allergies? One sure sign that they could be is that your dog is always itching. After preventive care, itching is the most common reason for dogs to see the veterinarian. Many dogs suffer from itching that causes them to scratch, bite, lick, rub and traumatize themselves - and it can drive everyone in the household a bit nuts!
If curing itching in dogs was simple or straight forward, veterinarians would have already done it and no dog would have to suffer. Sadly, figuring out what is causing the itch and what can stop it is often complicated and takes a lot of time, effort and money.
Your dog’s itch is just a symptom. The itch usually has a main underlying cause or primary disease such as:
- Allergies to things in the air, like pollen
- Allergies to food, usually protein
- Contact allergies
- Parasites, like fleas, scabies, cheyletiella or demodex
- Ringworm
- Autoimmune disease
- Cancer
The primary diseases and the associated trauma to the skin from scratching disrupt the normal protective barrier of the skin, allowing secondary disease such as:
- Bacterial infection
- Yeast infection
Additionally, anxiety, stress, and boredom can exacerbate the itching.
To successfully manage your dog’s itching, your veterinarian will have to do some tests to determine the primary disease and the secondary diseases. Remember, itching is a symptom, not a disease, and the most successful treatment involves identifying and treating the underlying cause. Your veterinarian will use a stepwise approach to try to get to the bottom of this challenging problem.
Step One - Your veterinarian will take a thorough look at your dog's medical history and ask what symptoms you are seeing to make a list of the most likely causes. Some common questions include:
- How old was your dog when the itching started?
- Is the itching getting better, worse or staying the same?
- Does the itch get better and then come back?
- Is it seasonal or nonseasonal?
- Has any treatment worked in the past?
Step Two - Your veterinarian will check for parasites. This may include combing thoroughly for fleas and using acetate tape and a scalpel to scrape the skin to collect samples to look at under the microscope for cheyletiella or demodex.
Step Three - Your veterinarian will look for the presence of bacteria or yeast by pressing a microscope slide on your dog’s skin, staining the slide and looking at the material under the microscope.
Based on the findings from steps 1-3, your veterinarian may choose a treatment that will likely be effective. This can include:
- Anti-parasitic medication
- Topical and/or oral antibiotics
- Topical and/or oral antifungal medication
- Topical and/or oral steroids
- Oral anti-itch medication
Step four - If your dog has recurrent episodes of itching or does not respond to therapy, your vet may recommend more even more tests. These tests can include:
Blood work. Your veterinarian will be looking for changes in screening blood work that suggests there may be an underlying endocrine disease. Some endocrine diseases like Cushing's disease and hypothyroidism make dogs more likely to develop skin infections. Diagnosis of these diseases may require further tests. Treatment for endocrine disease varies by disease.
Skin culture. Your veterinarian will rub a sterile swab over the affected area and will send the sample to the laboratory. In the laboratory, the material will be placed in a special dish with agar to see if any yeast or bacteria will grow. If there is growth, the lab may be able to identify exactly what type of yeast and/or bacteria is present and what medications are likely to kill them. Your veterinarian will make medication recommendations based on these results.
Skin biopsy. Your veterinarian will anesthetize your dog and surgically take a few small samples of the areas affected most. Your dog will likely go home with a few stitches. These samples will be sent to the laboratory to look at the skin itself for clues. These samples may reveal parasites, auto-immune disease, cancer or other causes of disease. Treatment will depend on the findings.
Food elimination trial. Food allergies can cause recurrent itching and skin infections. Most commonly, dogs are allergic to the protein component of their diet. To figure out if this is the case, and if so, what protein your dog is allergic to, your veterinarian may recommend a food trial. A food trial involves eliminating all food except the diet prescribed by your veterinarian. This food will contain only one protein - either a novel protein, like kangaroo, that your dog will never have eaten before or a hydrolyzed protein that has been treated so that your dog’s immune system will not react to it. You will feed this diet, and only this diet, for at least 6–8 weeks to see if your dog’s itching improves. If there is an improvement, then the old food is given to your dog for 7-10 days. If the itching returns when the old diet is fed, the diagnosis is made.
A blood test or intradermal skin testing for allergies to things in the environment. These tests look for your dog’s reaction to environmental allergens, such as grass, trees, pollen, mold, dust mites, etc. If your dog reacts to these allergens, your veterinarian may recommend “allergy shots” similar to those given to people.
If you are lucky, you may get to a diagnosis for your dog’s itching. While treating the underlying disease, your dog will need to also be treated for any yeast or bacterial infections with oral and or topical medications and will need relief from the itching.
As you can see, underneath what seems like a simple itch can be one or more very complicated diseases that cannot be relieved a simple "recipe" that will be effective in all cases. Just like in human medicine, a specialist may be necessary to get to a proper diagnosis and treatment for your dog's itching. A board-certified veterinary dermatologist can be found here acvd.org/tools/locator/locator.asp
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