Common mistakes in dermatitis case workups
In 25 years of talking to primary-care veterinarians about their struggles with dermatology cases, I am convinced that the major cause of frustration is time management.
In 25 years of talking to primary care veterinarians about their struggles with dermatology cases, I am convinced that the major cause of frustration is time management. Do you consider a dermatologic examination to be part of your complete physical examination, rather than a special procedure? If so, ask yourself if you can perform a thorough exam—skin, haircoat, mucous membranes, claws and claw folds, as well as the ear canal—in a 20-minute appointment and thoroughly follow up on any abnormal findings during that appointment? Probably not. In my opinion, a thorough dermatology examination and basic workup should be viewed as special procedures in the general practice.
Dr. Keith Hnilica speaks about his approach to practicing good dermatology when time is short. He advocates the "Three-Slide Technique," meaning that all dermatitis patients routinely get evaluated with three slides—ear cytology, skin surface cytology, and skin scrapings. But how do you manage this in an appointment slot that was originally scheduled for routine health maintenance? Here are some tips to help you bridge the gap between what you need to do and how much time you have to do it in.
Build in contingency time. In most cases, practice management style dictates the amount of time you'll have for a thorough dermatologic exam. Clients tend to save up non-urgent and chronic issues for their yearly examination appointments, and your goal should be to discuss and perform needed diagnostics while simultaneously handling health maintenance during the scheduled slot. It's important to try to handle the dermatology problem right then and there as opposed to rescheduling because clients frequently don't show up to the subsequent appointment. There are several ways to accomplish this. When a yearly examination reveals a chronic skin or ear problem, if your practice does not have the flexibility to turn a 20-minute visit into a 40-minute visit when issues that need to be addressed are identified, you could ask the owner to leave the pet at the clinic for the diagnostics to be performed when there is more time available throughout the day. Your veterinary technicians could also have enough time to handle unexpected issues so you can discuss the situation with the client, address the health maintenance issues, and begin your next appointment. You could design a convenient, quick, easy-to-complete check list for your dermatology form. Then you could add it to the medical record of any patient with dermatologic problems and assign a technician to collect these samples for that patient. I recommend that your practice handle these inevitable cases systematically —whatever system works for your clinic, as long as a trained staff member takes responsibility for making sure that all the steps are followed.
Don't skip skin surface and ear canal cytology. In dogs and cats with dermatitis and allergies, skin and ear ecology is upset. This leads to overgrowth of staphylococci or Malassezia, which leads to the exacerbation of allergic dermatitis and poor response to low doses of glucocorticoids. If you find these secondary problems it gives you an opportunity to stop the cycle. Scheduling a recheck examination allows you to assess the commitment level of the client, which is important to know in most dermatologic cases. It also allows you to see the primary clinical signs of the patient's allergy after secondary problems have been treated for a time. A more thorough discussion of the allergy can be had at recheck appointments as well.
Focus on compliance. The veterinarian and team members need to realize the importance of good flea control, especially with a patient with allergies. Whether or not the patient is actually flea allergic, flea bites are pruritogenic triggers that exacerbate other allergies; so rigorous flea control is paramount. The veterinarian can evaluate flea control challenges and recommend the best approaches, but these solutions also take time and a commitment from the client.
Don't assess flea control rigor by how much product the client buys. Instead, give them a flea comb to use at home, preferably on a household cat. A cat in the home of an allergic dog is a litmus test for flea control. If the client finds even one flea on the family cat, then the allergic patient is probably being exposed to flea bites. Include a thorough evaluation of flea-control practices and challenges in a household before making a recommendation.
Use the proper technique when performing skin scrapes. Occasionally, the harried practitioner uses a therapeutic trial to determine whether demodicosis is contributing to chronic skin disease. But Demodex is not an invisible parasite. If it is contributing to skin disease, it can usually be found with the proper skin scraping technique, which includes:
- Properly restrain the patient.
- Choose at least three good sites to scrape—lesions, preferably those with papules, patchy alopecia, or patches of comedones.
- Clip the sites to be scraped using a #40 blade.
- Pinch the skin at the site to extrude follicular contents.
- Scrape deep enough with a dull surgical blade or a spatula to produce capillary bleeding.
The latter two steps are somewhat painful and should not, in my opinion, be done in the presence of the client.
Perform DTM cultures. In cats, ringworm has many potential clinical presentations. In my opinion, virtually every feline dermatology patient should have a DTM culture of a properly obtained sample. The barriers that frequently block a DTM culture from happening are:
- Expense. The culture adds extra expense to a routine dermatologic workup so the practitioner must be prepared to explain why the possibility of ringworm should be eliminated early in the course of working up a skin problem.
- Technique. Some veterinarians are not comfortable with obtaining the right specimen for the best outcome in DTM culture. The bottom line is maximizing the amount of potentially infected material obtained and minimizing material that is potentially contaminated with saprophytic fungi from the environment.
» CLIP OR SCISSOR—TO ABOUT ONE-QUARTER INCH—THE LESION AND SURROUNDING AREA. GENTLY PAT THE AREA WITH A BARELY MOISTENED ALCOHOL SPONGE. THIS FURTHER REMOVES CONTAMINATION.
» PLUCK AND SCRAPE A LIBERAL SAMPLE OF HAIR AND SCALE FOR THE CULTURE.
- Interpreting the DTM results. This is an area that can cause much frustration. In some cases, the practice may want to send their inoculated media to a microbiology laboratory. If the DTM is to be incubated and evaluated in the hospital, the sample should be stored at around 78°F (25°C) and evaluated daily for the diagnostic color change. Someone in the clinic should be prepared to follow through with positive samples in seven to 10 days to make a microscopic identification of the suspect colonies as well.
When presented with a complicated dermatology case, remember to have a system, look for the underlying primary process, and keep allergies on your differential diagnosis list.