2015 Zoetis Excellence in Dermatology Symposium (NAVC/WVC)

2015 Zoetis Excellence in Dermatology Symposium (NAVC/WVC)

Sunday, January 18, 2015

The opinions expressed in these answers are those of the speakers and do not necessarily reflect the official label recommendations and point of view of the company or companies that manufacture and/or market and of the pharmaceutical agents, products, or services mentioned.

Cytology and Cultures: Successful Tips and Techniques to Implement Tomorrow

James O. Noxon, DVM, DACVIM

Once you lift up a collarette, how do you stain it? 
Once the collarette is peeled back, I usually make a direct impression of the area unveiled (taking care not to contaminate by pressing the slide against adjacent skin and hair). That impression is stained in a normal manner (alcohol fixative, xanthine stain, thiazine stain) using Diff-Quik stain.

Can you reuse sample brushes?  How clean do they need to be?  
You can definitely reuse the brushes. They tend to wear out after months….but you still get your money’s worth! They do need to be completely clean after each use, with NO residual materials left in the brush. I rinse them under a tap for 10 to 15 seconds and gently wipe them off with a paper towel. However, I do this once again, right before I use the brush….so I guess we “double clean” the brush each time.

Do cytology swabs need to be sterile? 
Obviously, you do not want micro-organisms on the swabs, so ideally the swabs should be sterile. Fortunately, most packaged cotton-tipped applicators are sterile when packaged, so they work fine. I do not re-sterilize swabs we purchase from regular distributors of products like that.

What magnification do you use for Malassezia? 
I actually scan all my yeast preparations with the 10x objective (which makes it 100x magnification) and I can spot them at that power. Scanning at that power also allows you to identify areas on the slide that warrant a closer look. For example, if I see clumps of white cells on low power, I definitely also look under oil immersion. Likewise, if I see clumps of red-stained cells (the xanthine from Diff-Quik), I look under oil immersion for Malassezia, which tend to like to hang out on those cells. HOWEVER, I would recommend that you review all slides under oil immersion (1000x) to confirm what you are seeing at lower powers. It takes a little more time, but the accuracy is worth it.

Microbiome DNA analysis of samples has begun to replace traditional cultures in the human sinus and wound care field. Do you see this as an option for DVMs? 
DNA analysis using polymerase chain reaction (PCR) or other techniques is not readily available, and certainly not at a price point that veterinarians will accept. We use those techniques primarily in research at this time. Maybe one day… These techniques are very sensitive, however, and there is some question that they might be too sensitive. Time will tell.

From Nose to Tail: Working Up the Itchy Dog

Valerie A. Fadok, DVM, PhD, DACVD

What is a pinnal‒pedal reflex?
We scratch or tickle the margin of the ear, and the dog raises its ipsilateral hind leg to scratch. This test is not pathognomonic for scabies but it is always important to treat cases with a positive pinnal‒pedal reflex to rule it out as skin scrapings are so often negative.

Do you see older dogs that have Demodex canis with underlying hypothyroidism?
Yes, we believe that some dogs that develop adult-onset demodicosis can be hypothyroid. It may be best to start treatment first, particularly if pyoderma is present, then run a thyroxine (T4), free T4, and thyroid-stimulating hormone (TSH) when the skin is more quiet, so we avoid the chance of coming up with a dog that has low values because of sick euthyroid syndrome.

What is the best way to get a cytology sample from around the eye, especially on a wiggly dog?
I like clear tape for this reason. You apply the tape to the skin, then stain in the pink and the purple parts of the Diff-Quik stain. You do not want to use the first part (light blue) as it is methanol and it will cloud the tape. Rinse with water after staining; then put the sticky side down on a glass slide and examine initially with the 10x and then with oil immersion.

What is a good topical medication for a periocular yeast infection?
I like to use the DOUXO® wipes around the eyes; they contain chlorhexidine and climbazole with phytosphingosine and are very easy for clients to use.

Do you treat lip yeast infections systemically?
I usually do at least initially because they are intensely itchy. I also use topical therapy at the same time. We then continue the topical therapy (using a wipe like DOUXO) to see if we can prevent yeast overgrowth. 

Concerning the photo of the nostril (see proceedings), would you still use oral antibiotics for such a mild lesion? 
I think that topical therapy for nasal mucocutaneous pyoderma is appropriate. Mupirocin ointment often is perfect for this purpose. 

What was the systemic antifungal you recommended? 
Terbinafine used at 30 to 40 mg/kg/day can be very effective in the treatment of Malassezia; however, Dr. DeBoer mentioned that he thinks that azoles work faster, and I agree. Still, the terbinafine is very economical and if we combine it with topical therapy it can work quite well.

Do you treat suspect dermatophytosis with oral medications before confirming with a culture?
I do if I have a positive Wood’s lamp examination, or if I find spores or hyphae when examining hairs microscopically. But I always do a fungal culture because I want to verify, and for lesions that don’t fluoresce, I like to know the species of fungus involved.

What about crusted pinnae that don’t itch? What would the differential be in cats?
Crusted ears that are not itchy in cats could indicate fungal infection or sometimes pemphigus foliaceus. We would have to see specific lesions to be more helpful. Occasionally I have seen bacterial skin infections on the ears as well. 

Have you ever used RESPIT®?
I have one patient on RESPIT (SkinVet Products) regionally specific immunotherapy because the owners did not want to pursue allergy testing. This dog has done quite well with it but I did modify it! My patient needed to have Staphage Lysate (SPL) as part of the allergy vaccine to do well. If your patient is allergic to molds or to microbial allergens then they may not do well with RESPIT. 

What is the youngest age at which you would do serum allergy testing and start immunotherapy?
We don’t have hard evidence for this, but I think that for patients less than one year of age we are more likely to get negative serum tests and positive skin tests. We have skin tested dogs as young as 5 months of age in my practice, and if we have ruled out other causes of itch, we start the immunotherapy. 

Are hydrolyzed diets better than limited-ingredient diets for food allergy trials? 
There is no one good elimination diet.  In my view, a novel protein diet is a better choice, but they are getting harder to find. There are examples in our literature of chicken-allergic dogs not doing well on hydrolyzed chicken diets—Hill’s Prescription Diet z/d®, and even a few patients on Anallergenic (Royal Canin)—and there are dogs allergic to soy that do not do well on hydrolyzed soy. Hydrolysis makes proteins smaller, but the immune system can recognize peptides as short as 8 to 15 amino acids long. In children with milk allergies, only about 85% tolerate hydrolyzed milk diets.

You mention both pyoderma and bacterial infection as causes of pruritus on the ventrum. What is the difference?
There is no difference. I use the two terms interchangeably.

What shampoo do you use on your dog’s lip yeast infection? 
I use chlorhexidine with climbazole (DOUXO) OR Miconahex-Triz (Dechra) OR Malaseb (DVM Pharaceuticals) on a washcloth. For owners who prefer wipes, we use DOUXO wipes or Miconahex-Triz wipes.

Global Innovations in Dermatology: Key Research Advances That Will Impact Daily Practice

Douglas J. DeBoer, DVM, DACVD

What are the possible side effects of Apoquel?
Apoquel (oclacitinib; Zoetis) is generally very well tolerated by dogs, and in field trials the adverse effects reported in the patients receiving Apoquel were comparable to the group receiving placebo pills. There are no specific organ toxicities with Apoquel. There are anecdotal reports from dermatologists who have used the drug of decreased white blood cell counts in a very few dogs—although not dangerously low. So for the moment, it seems prudent to recommend that a complete blood count (CBC) be performed every 6 months until we have further experience.

Why has Apoquel been back ordered for so long? Is it hard to make the drug?
Because of overwhelming demand, orders for APOQUEL continue to exceed the level of supply.  Zoetis remains on target to increase supply and begin making APOQUEL more widely available to new and existing customers in late April 2015.  More detailed information can be found on www.apoquel.com

What type of leave-on topical would you use with the frequent shampooing?
I prefer to use chlorhexidine; there is no evidence that the concentration is important (most products range from 0.5% to 4%) and there is no evidence that the addition of Tris or EDTA provides additional benefit. So, I would recommend whatever chlorhexidine product the owner finds easy or pleasant to use on the pet—spray, mousse, or leave-on conditioner formulations are all acceptable. The most important thing is that it is applied daily.

How long should you treat a pyoderma with antibiotics before you say the bacteria is resistant to that antibiotic?
With superficial pyoderma, there should be improvement within 1 week and clearing of lesions within 1 to 3 weeks. If new lesions are appearing during this time, or the lesions are not clearing 100%, resistance should be highly suspected. With deep pyoderma, improvement and clearing takes a bit longer—but if the pet isn’t improving within the first 2 weeks, culture is indicated.

 

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