Itching For A Diagnosis

by Dr. Robert Foley, DVM

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?"

Image Simon Winbles

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 approach to the veterinary patient. Their textbook, after all, would always be available for reference.

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

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 allergy 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.). 

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

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 times 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 breed.  

Labrador Retrievers, for example, are overly represented when it comes to food allergy. Wheaton Terriers, Bull Terriers (all pits), Jack Russell Terriers are a few breeds that are documented 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 the primary problem of itching. For example, steroids are often used to control outbreaks of itching from allergy. 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.)  Are there any other pets in the house?  Are those pets also itchy or are you itchy (signs of parasites)?  Are any other signs present like increased or decreased appetite, increased thirst (signs of underlying primary metabolic disease)? Are the problems seasonal or all year round?  (Food allergy symptoms, if the same food is fed all year, should be year round, for example).

Then there are just little pearls of knowledge which help.  

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

Ultimately, as is usually the case, Angryvet readers and South Bellmore Veterinary Group and East Meadow Veterinary Clinic patients, are encouraged to help with the diagnosis (by giving an accurate history) and paying attention to what is 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 times patients can be diagnosed by the 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 pets condition long-term. Once again, the relationship between Dr., patient, and pet owner is crucial.


Articles by Dr. Foley: 
Really Angry Vet: Winston's First Seizure  
Ruptured Cruciate Ligaments And Early Spay And Neuter