Why Does My Dog Itch: Itching For A Diagnosis

Why is your dog itchy? Don’t jump to conclusions.

Sometimes I like to surprise people by asking them, as soon as they walk in the room before they have even had a chance to introduce themselves, something like,

“What’s Max here for today, an ear infection?”

Visible clinical signs

The nice thing about dermatology is that dogs are literally coming in wearing their clinical signs. I particularly liked studying dermatology at school. While  I did read Miller and Scotts cover to cover (over 1000 pages),  I was more fortunate to attend lectures by both of these authors. These two lecturers (one of them who only wore tie-dye shirts, shorts, and Birkenstocks) had a way of cutting through a lot of dense material and focused more on the veterinary patient’s approach. Their textbook, after all, would always be available for reference.

It was important to look at your patient, get an accurate history, diagnose and treat infections, and perform the right diagnostics.

Diagnosing the itchy dog

Some of the lessons that they taught me are actually quite intuitive, and I can pass these on to you, the reader.


The first thing to note is how old is your patient.  

Young dogs (< 6 months) tend to have either food allergies or parasites (scabies, ear mites, Cheyletiella, etc.). Slightly older dogs (1-3 onset of development ) presenting itchy for the first time tend to be atopic (allergic to things inhaled such as dust mites, pollens, weeds, etc.).

Geriatric dogs presenting with severe skin problems often tell us that they are systemically ill with something else (like cancer or endocrine problems).

Body area

Also important is the distribution of the lesions.  

Dogs with inhalant allergens, for example, are often itchy in one or all of these three places:  the face (including the ears), the armpit, and the feet. Dogs with flea hypersensitivity chew around the base of their back near the tail, the tail, and under the tail. Often, these dogs will present with hotspots. Food allergic dogs can itch anywhere on the body and can mimic other diseases.

Pruritic (itchy) and also repetitively infected ears are common but not exclusive for food allergy.  

They will often have itching around the anus, mimicking anal gland problems. Dogs with scabies tend to have crusty, extremely itchy lesions around the ear tips and elbows. Greater than 90% of these will kick up their feet when you rub the ear tip between your fingers!


We also need to consider the breed.  

Labrador Retrievers, for example, are over-represented when it comes to food allergies. Wheaton Terriers, Bull Terriers (all pits), Jack Russell Terriers are a few documented breeds to suffer from inhalant allergy.  Brachycephalic breeds (dogs with pushed-in faces like Bulldogs ) often suffer from infections and itches in areas that other dogs don’t have, e.g., skin folds. Cocker Spaniels and others suffer from primary seborrhea (scaling and itching for no other reason other than they’re Cocker Spaniels).


Infections are common and can present either as primary causes of itching or can be present secondarily,  from the animal scratching and damaging his skin barrier, making him more susceptible to infection.  

In the latter instance, not treating the secondary infections can hinder your ability to rectify and/or control itching’s primary problem. For example, steroids are often used to control outbreaks of itching from allergies. Their use, however, can make clearing infections more difficult as steroids can suppress the immune response.  Thus we are left wondering why the patient is still itching even though we have given steroids.

The infection is still present or a new infection has developed.  

This is why when people call and say, “Hey, can I get the steroids that helped my dog last year for his allergies, we often say no (or at least plead our case to the owner). Cytology is necessary to document what infections are present and how they need to be treated.


A veterinarian that does not know how to or does not routinely perform cytology (from scrapings, swabs, and smears) is not worth her salt.


Taking a proper history is crucial.  

When did the animal first become itchy? (Cf. some age of onset examples above.)  Information that is important includes:

  • any other pets in the house
  • are those pets also itchy, or are you itchy (signs of parasites)
  • any other signs present like increased or decreased appetite, increased thirst (signs of underlying primary metabolic disease)?
  • Is the problem seasonal or all year round?  (Food allergy symptoms, if the same food is fed all year, should be year-round, for example).

Pearls of knowledge

Then there are just little pearls of knowledge which help.  

For example, when I first discuss food allergy, most people say, “He’s been on the same food his whole life.”  An allergen has to be developed, however.  It is chronic exposure that leads to hypersensitivity.

The first time you get stung by a bee, it hurts, the second time it swells, the third time you are getting the epi-pen in the Emergency room…).   

Another common misconception by pet owners, and we are seeing that right now, is that flea allergy is a summer problem when it is, in fact, much more prevalent and severe towards the end of the season in the late fall.

You can help with the diagnosis by giving an accurate history and paying attention to what’s working when we are treating the problem.

Unfortunately, many skin problems become recurrent, sometimes lifelong.  

Attentive clients can head off a lot of bad outbreaks by early intervention. I am a phone call away.  Often, patients can be diagnosed by phone or treated with brief rechecks. There is a lot that the owner can do at home (baths, grooming,  feeding, etc.) to help manage their pet’s condition long-term. Once again, the relationship between Dr., patient, and pet owner is crucial.

Related articles:
Allergies in Dogs: Common, Commonly Misdiagnosed, or Both?
Where Does It Itch? 3 Common Dog Allergies And How You Might Be Able To Tell Them Apart

Further reading:
My 6-Step Plan for Diagnosing & Managing the Pruritic Dog

Categories: AllergiesConditionsEar infectionsItchingSymptoms

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Dr. Robert Foley

Dr. Foley attended Cornell University’s School of Agriculture and Life Sciences, where he first met his friend, Dr. Michael Ferber. Dr. Foley graduated in 1992 and stayed in Ithaca after graduation to continue working in Dr. Alan Nixon’s laboratory at the NYS College of Veterinary Medicine. Together they studied the efficacy of chondrocyte implantion to treat osteoarthritis and osteochondritis dissecans (OCD) lesions in horses. In 1994, Dr. Foley was accepted into the NYS College of Veterinary Medicine at Cornell University. Dr.’s Ferber and Foley were reunited in vet school and became roommates. Dr. Foley graduated in 1998 and moved to Brooklyn, NY where he practiced for two years. Subsequently, Dr. Ferber invited Dr. Foley to come work with him at his family-owned practice, The North Shore Animal Hospital, in Bayside, Queens, and the two were reunited one last time. After two more years Dr. Foley became a partner within the group. The group decided to open up a new practice together on Long Island. Dr. Foley took a leading role in directing and growing this practice which became South Bellmore Veterinary Group. Over time the practice outgrew its original footprint and today operates as a beautiful, multi-doctor, 5000 square foot, state-of-the art, fully functioning animal hospital. Dr. Foley continues his role as Director of Medicine and Surgery of the practice today. His particular interests include dermatology, soft tissue and ophthalmic surgery. Dr. Foley is passionate about educating his clients on issues such as over-vaccination and the dangers of early spay and neuter.

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