Dermatology 101: How to approach a dermatology case
Obtaining a good history, physical examination and performing in-office diagnostics are necessary "starters" to each and every dermatology case. You will have more success in treating dermatology cases if you approach them systematically. Have a plan!
It sounds difficult-one more thing to have to do in a day with a million things to do. But, if you develop a step wise pattern to approaching patients with dermatology problems, after awhile, the steps will become automatic.
If you haven't already realized it, dermatology cases take a lot of time! The number one step should be to have your receptionist schedule a few extra minutes or even double the time allowed for the appointment when he/she hears that the problem is skin related.
Allot enough time
Since most dermatology cases, perhaps more so than the other specialties, require obtaining a good history from the owner, extra time is necessary to obtain this history. In large, multi-veterinarian practices, try and have the same doctor see the patient each time. This is important for many reasons but mostly to have one doctor manage the case and oversee all the therapy that has been or is being administered.
Unfortunately, some cases suffer from overuse of steroids due to the fact that many doctors in the same practice see the patient in a short amount of time, and no one actually sits down and goes over the chart thoroughly.
Important points to consider are not only the chronic steroid use but seeing if a pattern is emerging regarding the time of year the patient is affected and other factors such as multiple pets affected, human family members affected or whether or not the disease is steroid responsive.
Obtaining a good history cannot be emphasized enough. As we all know, in some cases the client tells us everything except the answer to our question. It is up to us to ask the same question in different ways to obtain the answer.
The first question I ask the owner is how long has the patient had the skin problem? At the same time, I am observing the age of the patient, breed, areas of the body affected and whether the patient is pruritic in the exam room.
Age of onset is important since atopy in most patients begins from 6 months of age to 3-4 years old (some exceptions, of course). Atopy also usually involves face, feet and rectal area, whereas a dog with pruritus and lesions in the lumbar and rear leg/groin areas is suspicious for flea allergy dermatitis.
Since atopy is hereditary, we tend to see it in the same breeds, i.e. Retrievers, Terriers, herding dogs, Shepherds, oriental breeds, Spaniels and Dalmatians.
Are there other pets in the family and, if so, are they having skin problems? This question, if answered "yes," may indicate the presence of a contagious disease like ectoparasites. Also consider if the pet is exposed to other animals either via grooming or kenneling because exposure to ectoparasites can be present in those environments.
Along the same line of ectoparasite exposure, the question of the home setting should be asked-does the pet live in a rural setting? Allowed to roam freely? Are there cats in the household that go outside, barn cats or does the dog go to the horse barn?
Once the age of onset, home setting and inquiry about other pets in the household is made, questions should be asked about the seasonality of the problem-nonseasonal, started seasonally and is now nonseasonal, or strictly seasonal.
Response to past therapies should then be discussed. Was the pet responsive to steroids? Antibiotics? If fleas were a problem, was the pet on a flea treatment program and did the owner understand what was involved in a complete flea treatment?
The second step in solving the mystery is a thorough physical examination. This goes without saying no matter what the presentation of the patient is to the veterinarian.
Even though the patient may be seeing our office for a skin problem, we still check that patient thoroughly, particularly our geriatric patients.
I remember one middle-aged Basset Hound referred to us for skin testing. While examining the dog, I discovered she had lymphoma. The work up for atopy was postponed while the life-threatening disease was addressed.
A good physical examination is important for many reasons, one of which is that certain medications cannot be prescribed when underlying diseases are present.
In dermatology, some antihistamines can increase intraocular pressure and that would be contraindicated in dogs with glaucoma. Phenothiazine derivatives should not be used in epileptics. Antifungals can be teratogenic and consequently should not be used in animals going to be bred. Other aspects of the physical examination that yield clues to a dermatologic disease include alopecia. Is the pet pruritic and causing the alopecia or is the hair falling out? Have steroids been used recently as they cause a resting effect on the hair growth cycle resulting in hair loss with delayed regrowth.
Signs of iatrogenic or naturally occurring Cushing's disease include a pot-bellied appearance, thin skin that bruises easily with visible vessels particularly on the abdomen, a fine "peeling" of the skin and recurrent bacterial pyoderma. Conversely hypothyroid patients may have a thickened feel to the skin, appear depressed "tragic facies", bilaterally symmetrical alopecia with hyperpigmentation, and lack of undercoat with hair loss beginning over points of wear. With either disease, the signs and symptoms can be extremely subtle, particularly early in the disease.
There are many in-office diagnostics in dermatology that take very little time and can yield quite a bit of information. Every pet that we see gets combed, scraped and smeared. Combings are performed with a flea comb not only looking for fleas or flea dirt, but also to pick up Cheyletiella mites, lice, poultry mites or feline demodex gatoi (lives superficially).
The combings, consisting of hair and dander, are then observed under the microscope in oil under low power. It is important that the patient was not recently bathed prior to the appointment or the ectoparasite will not be found.
Also consider that you are seeing the patient that is affected with the skin problem when another pet at home may be asymptomatic. Cheyletiella mites can involve asymptomatic carriers, so it may be necessary to see the pet without the skin problem to thoroughly rule this out. Skin scrapings should also be performed on all patients particularly in areas of crusting, scaling or alopecia.
If you do nothing else, be sure to perform skin scrapings to rule out demodex or scabies. Scrapings are placed in oil, topped with a cover slip and observed under low power. Skin and ear smears obtained from nailbeds, ears and skin folds yield the presence of microorganisms such as yeast and bacteria. The smears are performed using Q-tips or scalpel blades and pressed into a glass slide which is heat fixed then stained with Dif-Quik.
Ear smears tend to yield the most rapid information as to which microorganisms and in what amounts are present in the existing ear infection. Ear smears in oil will detect ear mites or demodex mites affecting the ear canal. Do not confuse an ear smear with an ear culture!
An ear smear yields instant information about what is there and in what amounts, whereas an ear culture takes at least three days to gain results. Ear cultures should be performed when rod bacteria are present as an antibiotic sensitivity is necessary to see what the bacteria will respond to. Cultures should also be performed when an existing treatment is not successful.
Dermatology 101 may sound elementary but if it gets you in the habit of approaching a dermatology problem with a plan, your outcome will be more successful. It is time intensive because a good history and physical examination are absolutely necessary, yet performing the in-house diagnostics mentioned above take very little time.
If you do not feel familiar with performing ear smears or skin smears-start doing it! Along with a dermatology or cytology book to guide you, you will be surprised at the information cytology yields. The best way to become good at it is to start doing it on each patient you see. You can double check yourself by submitting some of your slides to your local pathologist. M
Dr. Jeromin is a pharmacist and veterinary dermatologist in private practice in Cleveland, Ohio. She is a 1989 graduate of The Ohio State University College of Veterinary Medicine and an adjunct professor at Case Western Reserve University's College of Medicine in Cleveland.