Why Is My Dog Itching So Much? Possible Causes and Dog Itch Relief

Do you have a dog who's itching excessively? 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 dog itch relief. If you're just starting to scratch the surface of your dog's itch issue, here are some potential causes and treatments to know.

Causes of itching in dogs

Why is my dog so itchy? 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 aren't 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 a dog itching excessively 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 your dog? It is common to start with an allergy pill, such as an antihistamine (e.g., cetirizine or hydroxyzine), prednisone (the steroid), and shampoos. Sometimes, one of these solutions is the magic tonic. But if the itching isn’t resolved by these methods, more intensive work needs to be done. 

Diagnostic tests for itchy dogs

The following are the steps that Best Friends Animal Society's 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 it might point to further testing. A thyroid level test can tell whether a dog has a low thyroid (hypothyroidism), which is a relatively common cause of skin disease in dogs. Also, doing skin scrapings to look for mites is important, as is testing for ringworm in suspicious cases.

Diet trial for dog skin problems

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, they might do these biopsies even before trying the above. 

Allergy testing for dogs

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 and supplements

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 for the skin. And a wide array of other nutritional supplements and herbal remedies are available. Always discuss with your vet before trying any remedy. 

Veterinary dermatologists

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 might never be cured. But many times it can be managed so that the animal enjoys a good quality of life.