The itchy dog can be one of the most aggravating, persistent, and frustrating conditions for dog, client, and veterinarian.
Many things can cause dogs to itch, including:
- Atopic dermatitis or hypersensitivity to dust, pollens, molds, dander, and/or grasses.
- Parasitic allergies, including flea allergy dermatitis.
- Food allergies
- Bacterial dermatitis
- Fungal or yeast dermatitis
- Immune-mediated dermatitis (lupus)
More than one of these conditions can occur concurrently, complicating diagnosis and treatment. Allergies can occur at any age. Very few patients are cured. More often, allergies need to be managed for the duration of the patient's life, minimizing and controlling symptoms so that they are bearable.
It is helpful know what causes the itchy dog to itch. Below is a list of some of the diagnostic tests that might be recommended and what they will tell us about the patient.
- Skin scraping: looks for microscopic parasites such as scabies or demodectic mange.
- Cytology: looks for opportunistic bacteria and yeast; also looks at superficial cells.
- Complete Blood Count (CBC): blood test that helps to assess the patient's immunity.
- Allergy testing: blood test that measures the patient's sensitivity to a panel of environmental and food allergens.
- Culture and sensitivity: identifies specific bacteria harvested from the patient's skin and tests it reaction to different antibiotics.
- Skin biopsy: microscopic evaluation of the patients skin at superficial and deeper levels.
Treating infectious skin diseases:
Once the offending parasite, bacteria, or yeast is identified, treatment is usually straight-forward. Depending on the severity, skin can be treated from the inside out (drugs), or the outside in (shampoos, salves, sprays, other topicals), or both.
Recurrent conditions often indicate an underlying allergy or hypersensitivity.
Managing allergies and hypersensitivities:
There are many approaches to managing allergic dogs. None of the options is certain to benefit every patient and some have more potential side effects than others. Some work quickly and some take more time. Some are more costly than others and some involve more work than others. Sometimes several options need to be tried before finding the right one for that individual.
So in no particular order, here are some of the ways in which atopy has been managed:
- Avoidance or minimizing exposure. First, testing is done to determine the patient's specific allergies. Exposure to certain allergens might be controllable, such as certain foods, or dust mites, or trees, or grasses. Air filters can reduce the concentration of indoor dust or pollens. Dehumidifiers can reduce mold. Frequent bathing and wipe downs with moist cloths can reduce allergens that attach to the patient’s body. Avoidance alone may not be adequate or possible depending on the patient and the environment, but when it is, it can be a very natural approach to helping the patient.
- Immunotherapy is as close as we get to curing patients with allergies. Traditionally, immunotherapy begins with allergy testing. Once we know what the patient is allergic to, the goal of immunotherapy is to very slowly desensitize the patient to those allergens. Traditionally, this was done through a series of injections of a very small amount of allergen with gradual increases so that the patient builds tolerance to the allergen. More recently, there are versions of immunotherapy that are given orally. Immunotherapy benefits approximately 60-70 percent of patients. Some patients improve within 3-4 months, while others can take longer. It is generally recommended that immunotherapy be tried for 6-7 months before deciding that it is not benefiting the patient. Maintenance therapy every 1 to 3 weeks throughout the patient’s life is not uncommon. Serious adverse effects are extremely rare, but possible. Patients should be monitored for 15 minutes following each treatment, especially in the beginning.
- Food therapy: Hypoallergenic diets will be more beneficial for patients with concurrent food allergies (estimates range from 10-30 percent). Blood testing for food allergies is available. In theory, a hypoallergenic diet should be made of “virgin” ingredients that the patient has never encountered before. As more exotic flavors of pet food enter the market, finding diets made up of only these “virgin” ingredients is more challenging. Some of the newer hypoallergenic diets utilize ingredients such as zebra, duck, barley, potato, rabbit, and avocado (not all in the same diet, of course). Ideally during a food trial, the test diet is the only food that the patient gets for 8-12 weeks.
- Some people advocate diets that use human grade ingredients, are less processed, and include fewer preservatives than kibble. There are some of these more wholesome diets commercially available, such as Wysong, Honest Kitchen, and Wellness. There are also many recipes for homemade diets (please make sure you include the vitamin and mineral supplements). Personally I like the idea of feeding my non-human companions a more wholesome diet and some atopic patients do improve with these types of diet changes. However, I have also encountered many atopic patients that continue to have atopy even on these more costly, more difficult to obtain, and/or more labor-intensive meals.
- Bathing: Frequent bathing is a really nice option for some dogs. It removes allergens from the surface of their body, and decreases populations of the bacteria and yeasts that like to overgrow in these patients. Shampoos should be selected appropriate to the patient's skin and coat condition. For a patient with “damp” or moist or greasy skin, a good cleansing shampoo to cut through that grease – dishwashing liquid, or shampoos with aloe vera, benzoyl peroxide, and/or sulfur tend to be drying (and also good for bacterial and yeast skin infections). Patients with very delicate or dry skin would do better with baby, oatmeal, or moisturizing shampoos. Patients with really thick coats may need to be blow dried.
- Vitamin E: Benefit patients with a tendency towards dry skin and dry or brittle coats. Vitamin E is also noted for its anti-inflammatory and anti-oxidant benefits. Vitamin E and Omega 3 fatty acids are known to compete with each other so if both are given, they need to be given separately (one in the morning and the other in the evening).
- Antihistamines: The most commonly used antihistamines in veterinary medicine are diphenhydramine (OTC: Benadryl), chlorphenarimine (OTC: Chlortrimeton), and hydroxyzine (prescription item). Like all other treatment options for atopy, response is variable. A few patients experience dramatic improvement; some partial improvement; some no improvement at all. Some respond better one rather than another. Overall, I’ve seen estimates that between 30 and 60 percent of patients improve. And like all other treatment options, the only way to know is to try. Antihistamines are generally well-tolerated and safe; however, I do have concerns about patients that require high doses starting at a very young age. Long term studies are limited. Some patients become very drowsy on antihistamines. Indeed, I have had client question whether their dog no longer scratches because s/he doesn’t itch or because s/he’s too drowsy (which may be a good night time option).
- Corticosteroids: Prednisone is one of the most-reliably effective prescription drugs for managing the itch. However, steroids come with a long list of potential adverse effects, especially with high doses or extended use, or in sensitive patients. Increased thirst and urination, increased appetite and weight gain are the most commonly observed side effects. Sometimes personality changes such as increased anxiety or aggression are observed. Prednisone can worsen any bacterial or yeast infections. Gastric ulceration and decreased clotting (causing spontaneous bleeds) have been reported. Changes in liver chemistries are commonly observed in patients on prednisone. Prednisone can lead to diabetes and/or Cushing’s disease. Taking prednisone in conjunction with any NSAIDS (aspirin, Rimadyl, Etogesic, Deramax, Previcox, Meloxicam) will increase the likelihood of adverse effects and is emphatically not recommended.
When prednisone is chosen to manage patients with allergies, I advocate using the lowest possible doses, careful patient monitoring, and semi-annual blood tests to avoid long term complications. There is combination prescription drug product called Temaril P that includes 5 mg of an antihistamine called trimeprazine and 2 mg of prednisone. The combination appears to have synergistic benefits in many patients, providing more relief than antihistamines alone and using a much lower dose of prednisone. Both Prednisone and Temaril P are prescription drug products.
- Modified cyclosporine: Atopica is a FDA-approved non-steroidal immunosuppressive drug first used in organ transplant patients, so that they wouldn’t reject the donor tissue. Atopica appears to be quite effective in controlling atopic itching. Atopica causes 30% of patients to become nauseous and vomit. 7.8 percent of patients develop elevated kidney values after being on Atopica for a month. It would be prudent to check blood chemistries before starting and one month after starting Atopica. Atopica is an immunosuppressive drug and studies on long-term use are limited.
- Olclacitnib: Apoquel is the newest FDA-approved drug for treating atopic dermatitis in dogs. It is described as "not an antihistamine and not a corticosteroid." It's really a new class of drug that hasn't really been defined yet. Pharmacologically, it inhibits cytokines (proteins that mediate between cells) that cause itch and inflammation.
- Chinese herbals: In Chinese herbal medicine, herbs are selected in combination to alleviate itch (wind) as well as to balance the patient's overall constitution as determined by a practitioner trained in traditional Chinese Veterinary Medicine (TCVM). Components such as dry skin or damp skin, heat or coolness, odors, deficiencies or excesses, what parts of their bodies are most affected, and other ailments or health issues are factored into the herbal selection. Serious side effects are rare, but can occur with certain Chinese herbs and formulas.
- Homeopathic remedies: Homeopathy is energetic medicine more than physical medicine. Homeopaths accept that there is a vital force associated with each physical body and that diseases and symptoms arise when there is a disorder in this vital force. Homeopathic remedies are used to correct derangements in the vital force. They are extreme dilutions (such that they are absolutely non-toxic) of substances known to cause the symptoms that the patient is experiencing. The homeopathic Law of Similars states that whatever symptoms a substance can cause, it can also cure. Both chemists and homeopaths claim that physically, remedies are 99.99% or greater water and cannot cause adverse effects even if overdoses. Homeopathy, like other treatments mentioned on this page, is not for everyone, but I am asked about it often enough that I felt it should be included in a thorough evaluation of options.