Itchy Dog: Causes and Treatments

Do you have a dog who’s constantly scratching? The itchy dog is one of the most difficult problems to assess in veterinary medicine. It is often hard to find the underlying cause and even when found, it often involves lifelong therapy for the dog.

Causes of itching in dogs

Decades ago, the most common cause of itchiness in dogs was fleas. This is less of a concern nowadays with improved flea control products, but if you are not using a flea control product, start with that. Even if you don’t see fleas, it doesn’t mean they are not there. The best flea control products are safe and can provide substantial benefits. Consult with your veterinarian about which product is best for your dog.

Today, the most common cause of itchiness is allergies. But the challenge is this: What is your dog allergic to? And, once that substance has been identified, what is the best way to treat her? It is common to start with an allergy pill such as an antihistamine (like cetirizine or hydroxyzine), prednisone (the steroid) and shampoos. Sometimes, one of these solutions is the magic tonic. If the itching isn’t resolved by these methods, more intensive work needs to be done.

Diagnostic tests

The following are the steps that Best Friends’ vets recommend. The order is variable, based on the signs the dog might be showing and what has or has not worked.

Some standard diagnostic tests can be done. A CBC (complete blood count) and chemistry profile can detect systemic disease and infections. It can also give clues to endocrine diseases that can cause skin disease, such as hyperadrenocorticism, overactive adrenal gland, and may point to further testing. A thyroid level test can tell if a dog has a low thyroid (hypothyroidism), which is a relatively common cause of skin disease in dogs. Doing skin scrapings to look for mites is important, as is testing for ringworm in suspicious cases.

Diet trial

If initial treatment does not work and standard diagnostic tests don’t reveal an answer, a diet trial is a possible next step. The diet trial, which should be done for at least six weeks, is based on the fact that many dogs are allergic to the protein or grain sources used in many standard dog foods. During the trial, the dog is fed a novel food with unique protein (such as salmon or duck) and carbohydrate (such as sweet potatoes or peas) sources. It is vital that only this food be fed to the dog. Even a small treat of a non-novel food can cause allergies to flare up.

To stop the self-perpetuating itch and scratch cycle, the dog is generally kept on the prednisone or antihistamine at the start of the diet trial. The reason for this is that once a dog starts itching, the scratching can initiate its own inflammation, which causes the dog to itch even more. So, even if the offending allergen is gone, the dog will continue to itch.

Dog itch treatments

Dogs with allergies commonly get secondary skin infections — either bacterial or yeast in origin. It is quite likely that the dog will need to be on antibiotics, antifungals (for the yeast) or special shampoos for up to six weeks. If these infections are not treated, the itchiness will persist even if the cause of the itchiness is removed.

If routine lab work is normal, and medications, flea control and diet do not fix the problem, one of two things can be done. If there are persistent skin lesions, they can be biopsied and cultured. In doing this, your veterinarian will look for autoimmune diseases, resistant infections or atypical forms of standard diseases. In some cases, if the vet is suspicious of something abnormal, he/she may do these biopsies even before trying the above.

Allergy testing

The other thing that your vet might do at this point is an allergy test. Dogs can be allergic to food, but they can also be allergic to things outside, such as pollen, grasses, mites, trees and more. There are two ways to go about testing for what a dog might be allergic to. The first is a blood test that checks for antigen levels to common allergens. This is fairly simple and most veterinarians can do this.

The other way is to do intradermal skin testing, which is done by giving injections of allergens under the skin and measuring the response. Most veterinarians can’t do this test; it is mostly done by veterinary dermatologists. If causative allergens are identified, the treatment is administering hyposensitization injections (allergy shots), which are normally given for the rest of the animal’s life. However, they can be expensive and difficult for some people to give.

Immunosuppressive drugs, supplements and other remedies

Sometimes the dog can be given a more potent immunosuppressive drug, such as cyclosporine. The drug can dampen the immune response so that the animal is not as reactive to an allergen. There is also a relatively new medication called Apoquel that is intended to help with allergies and may have fewer side effects. Some supplements, such as fish oils or other fatty acids, can be extremely beneficial, and a wide array of other nutritional supplements and herbal remedies are available.

Veterinary dermatologist

When it comes to treating an itchy dog, the gold standard is to go to a veterinary dermatologist. These specialists can pinpoint treatment and do the intradermal skin testing if they think it is indicated. At Best Friends, we often recommend referral in refractory cases or in cases when people are at their wits’ end. Many of these cases require lifelong therapy and the condition may never be cured, but many times it can be managed so that the animal enjoys a good quality of life.