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Posted on Wed, Aug 14, 2013 : 7:30 a.m.

The itchy dog - diagnosing cause helps pinpoint appropriate treatments

By Lyssa Alexander, DVM

Thumbnail image for Dr. Alexander- August 2013- Itchy Dog.jpg

Photo by Flickr user LOLren

The end of the summer is a beautiful time. The plants are mature and the fields are abloom with gorgeous yellow and purple flowers. It is truly one of my favorite times of year.

Unfortunately, for many of our dog friends, the end of the summer comes with bad allergies. Dogs who have environmental allergies can react at any time of the year, depending on what they are allergic to. However, this time of year seems to bring me a lot of itchy pets.

Humans are no stranger to allergies. Many of us can chart the change of the season with levels of snot and congestion. Though our allergy symptoms overlap quite a bit with what we see in dogs, the main presentation of an allergic dog is itching.

They lick their paws (major sign of itching), scratch their bodies, shake their heads and get widespread skin and ear infections. For many dogs, these signs are mild, and they come and go with the season. However, many dogs can develop debilitating skin and ear infections or are simply too miserable to sleep. These are the dogs that come through my doors in droves.

When an itchy dog walks through my door, the first step is to try to determine if they have any infections. Regardless of why they are itching, hot spots, skin infections and ear infections can develop. Dogs with ear infections will have debris, inflammation and a foul smell in their ears and will exhibit head shaking or pawing at the ears.

Skin infections will take the form of scabs, ulcers and crusting along any part of the body. The skin is a complex organ with many important jobs. Besides keeping your insides on the inside, the skin also has to serve as a complex cellular barrier against naturally-occurring yeast and bacteria in the environment.

Every dog and person has low numbers of these organisms living on their skin at all time. However, for most of us, the skin's barrier function and intelligent immune system keep these organisms in check. When the skin is inflamed and immune compromised, the yeast and bacteria grow to impressive numbers and cause even greater levels of rashes and itching.

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Photo by Flickr user GCSE Jack

Once we have diagnosed and treated the infections that come along with itchy conditions, we need to determine the underlying cause. Sometimes this is easy and sometimes it takes a lot of time and patients.

The most common reasons for an itchy pet are environmental allergies, food allergies, flea allergies, ringworm infections and mange. Other less common reasons include local reactions to insects or chemicals or certain systemic illnesses and immune conditions. Cats also get a similar variety of itchy conditions.

Environmental allergies or (Atopy or Atopic Dermatitis) is by far the most common itchy condition in dogs. There is usually a history of recurrent itchiness or skin and ear infections that come and go throughout the year. As a dog's immune system matures, their allergy season may change or expand.

Dogs can be allergic to almost anything (just like people). Some of the main offenders are pollens, grasses, plant materials, dust, dust mites, molds, cats and insects. For many pets, we can decrease their itching through dietary supplementation, environmental management, antihistamines (please ask your veterinarian before giving your dog any medications) and judicious use of steroids for short periods of time.

For animals with severe allergies, more elaborate measures are needed. For these pets we recommend either going on a long term medication protocol with an immune modulating agent or starting a series of vaccines to try to desensitize their immune system to the allergens that are most offensive to your pet. Both of these strategies have their pitfalls at times, but for miserable dogs they can be lifesaving.

Another leading cause of itchy pets is food allergy. This is a well recognized condition that has been a bit twisted by dog food marketing. You can't walk down a pet food isle without encountering bags that advertise “grain free” diets or “low allergen formulations.” Though wheat and corn are common food allergens in dogs that are truly food allergic, they are by no means the only offending ingredients. Diagnosing a food allergy in dogs can be tricky.

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Photo by Flickr user Misserion

The best way to diagnose food allergy is to do a strict food allergy trial. This can be done with various veterinary prescription diets, but is most effective when done with a strict home-cooked diet formulated from novel ingredients (ask your vet for advice on how to do a trial). If an itchy dog clears up on the food, it is important to challenge them with their previous diet to make sure that the food was really the cause.

I have seen a lot of people switch their pets' diets in the fall and see a big improvement. But many dogs with environmental allergies get better as the winter sets in anyway, so it is hard to say why the dog actually got better without doing a proper challenge at the end of the trial. For dogs with true food allergies, finding the right diet can be life-changing.

Flea allergies are also fairly common. hen a dog is heavily infested with fleas they can be quite itchy. However, dogs with flea ALLERGIES only have to be bitten occasionally to become wildly itchy. It can sometimes be a big challenge to convince owners that their dog has flea allergies when they haven't seen any fleas.

Depending on the dog's environment, even if they are on a good flea preventative they can get an occasional flea bite that can cause a flare-up. These cases can be frustrating at times, but as long as we keep them as flea free as possible, they can usually be managed well.

Mites and ringworm infections are also somewhat common, especially in puppies. Some of these conditions can spread to humans. Scabies mites cause dogs to be extremely itchy, especially on their ears. People in contact with scabies mites can develop itchy red rashes.

Demodex mites can cause widespread hair loss and skin crusting, which may or may not be itchy. Mites are generally diagnosed by skin scrapings performed by your vet.

Ringworm can look very similar and also causes variable levels of itching. In people, ringworm often causes a characteristic red ring lesion. Treating ringworm and getting it out of your environment can be a nightmare, but is worth the effort to keep you and your pets safe. Ringworm is generally diagnosed with a culture.

There are lots of reasons for a pet to be itchy. If your pet is licking its feet, shaking its head, itching its body or looking rough, don't hesitate to take them in. It is important to make sure that they don't have any diseases they could pass to you and to treat the cause of their itch as soon as possible. They'll thank you for it.

Lyssa Alexander, DVM treats small and exotic animals and pocket pets at All Creatures Animal Clinic.



Thu, Aug 15, 2013 : 1:11 p.m.

Our dog has big floppy and hairy ears that are always getting a yeast infection in her ears which is very smelly . We have tried expensive vet prescriptions , home remedies and even vagisil which helped the most along with a healthier food formula What ever we do it comes back.


Thu, Aug 15, 2013 : 1:16 a.m.

Thanks for the article.