Why Is My Dog So Itchy?

By: Alex Betzen, DVM

TVMA Member
Houston, TX.

Published May 2015

Skin conditions account for approximately 20 percent of the patients presenting to veterinary hospitals. “Why is my dog so itchy?” is one of the most common questions we get!

What Are the Signs of Itchiness and What Causes it?

Dogs presenting to the hospital with itching (pruritis or pruritic) often have other skin problems as well. Other conditions we see with itching are hair loss, redness, scaling, flaking or crusting skin, external parasites, superficial skin infections (bacterial and yeast infections) and others. Often we see many of these signs together.

These multiple signs can make it challenging for the owner and the clinician to determine the original cause of the itching. For example, dogs with food allergies can show signs of their disease with itching. Often, these dogs will scratch themselves to the point of having mild superficial skin infections of yeast, bacteria or both. These yeast and bacterial infections worsen the itchiness, making for a very itchy dog and a difficult case to solve. Imagine if this dog hasn’t been on appropriate flea control, which means we’ve got a real puzzle.

There are many common causes of itchiness in dogs, and there are several questions your veterinarian will ask you. These questions may include: Have you noticed seasonality to the itching? Did it start after recently switching foods? Has your dog historically been itchy, or is this the first time? Where is your dog specifically scratching? How old is your dog, and what breed is it? For example, ringworm, scabies and red mange (Demodex) are much more common in juvenile animals than adults.

Don’t Forget About Fleas

Flea control can be extremely important for the itchy dog. When you come to your appointment, it is important to know which flea preventative your dog is on, when you last applied it, how you applied it, how frequently you bathe your dog (many flea control products lose effectiveness in the third and fourth week, especially with frequent bathing) and what environmental controls you are using. It is very important for the itchy dog to be on an appropriate flea control year-round in a warm and humid climate. Please keep in mind that indoor-only cats are often exposed to fleas, especially if there is a dog in the house. Keep them on flea control too. Please read the label on your flea control products. Some of the dog flea preventatives are toxic to cats.

How is Itching Treated?

After a thorough history to help us determine the cause of the itching, the veterinarian will start the physical exam. During the physical exam, we are looking for characteristic lesions or signs that might help us determine the cause of the itching. For example, dogs with environmental allergies often chew and lick their paws. If there is hair loss or scales, the veterinarian may perform a diagnostic skin scraping. Often we will scrape more than one area to make sure that we get representative samples. The scraping may need to be repeated at follow-up appointments if the lesion is not resolving.

We may also use a tape impression. The test is as simple as using clear tape applied directly to the lesion, then to a slide and then examined with a microscope. More expensive but sometimes necessary tests include skin cultures and skin biopsies.

Once the cause of the itching is determined, a treatment protocol will be initiated. The protocol is designed to treat the underlying cause (e.g., external parasites, superficial bacterial or yeast infections, dietary trial, medicated baths). The veterinarian may also prescribe medications to alleviate the itching while the cause is treated (i.e., antihistamines and steroid therapy).

It is very important to understand that many of the causes of itching have overlying signs. For example, dogs with food allergies, flea allergies and environmental allergies have hair loss and superficial skin infections. The location of the hair loss and history can help the veterinarian decide which is most likely, but sometimes it takes a therapeutic trial. Therapeutic food trials for skin typically require two to three months before improvement can be recognized. If the dog doesn’t improve, it is time to evaluate the treatment protocol and suspected underlying cause and make adjustments.

Below is a list of some of the most common conditions to discuss with your veterinarian.

Common causes of itching in the dog:

  • Superficial skin infections, such as yeast or bacteria
  • Mites, including canine follicular mite (Demodex) or scabies (Sarcoptes spp.), lice or walking dandruff (Cheyletiella spp.)
  • Allergies, such as environmental, food or flea
  • Contact dermatitis

Luckily, itchy dogs can often be cured or successfully managed. It is important to recognize that many of the causes of itching are not contagious, but some are (such as scabies and flea bites). Also, there are very few true dermatologic emergencies, so the appointment for the itchy dog can be made within two to three days of noticing the signs relatively safely.

Alex Betzen, DVM, is a graduate of Kansas State University College of Veterinary Medicine, who practices at Westbury Animal Hospital in Houston, Texas.