A panel of board-certified veterinary dermatologists has developed a standard procedure to help diagnose secondary and primary infections related to canine dermatitis. It’s important to perform the 3-Slide Technique™ at the first signs of dermatitis and at every recheck. This can help ensure that every dog is receiving the very best care possible. Plus, having a technician perform the technique can save time in the examination and diagnosis process.

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The Setup
Wax Smears and Staining
Scrape Smears Staining
Tape Prep and Staining
Direct Skin Impressions and Staining
Through the Microscope
Who, What, Where and Why
Examination Form

The Setup:
Prepare a histological staining station similar to a Wright Giemsa or Romanovsky stain.

1. Alcohol fixing agent (blue)
2. Eosinophilic staining agent (pink)
3. Basophilic staining agent (purple)

There is a commercial stain available called Diff-Quik® that comes in kits for purchase. Keep in mind that you’ll want to use glass beakers.

Staining Protocol:
There are 3 different staining techniques used in the 3-Slide Technique™: a wax smear, a scrape smear and a tape or impression smear.

Wax smears are ear swabs that can help rule out otitis and other infections:

1. Collect your smear using swabs in each ear canal.
2. Put the right ear swab on the right side of the slide and the left on the left.
3. Heat-fix the sample before staining by burning the underside of the slide.
4. Remove the sooty residue.
5. Dunk the slide into the fixing agent 15 to 20 times.
6. Dunk the slide into the Eosinophilic stain 15 to 20 times.
7. Dunk the slide into the Basophilic stain 15 to 20 times.
8. Rinse with tap water.
9. Allow to air dry.

Scrape smears are usually concentrated in infected areas, especially the lumbar region, and can help rule out demodex and other infections:

1. Collect your smear using a scalpel on an infected area of the lumbar region.
2. Scrape in the direction of hair growth until you see small pearls of blood, squeeze and scrape again.
3. You should scrape every infected area with all scrapes on one slide.
4. Dunk the slide into the fixing agent 15 to 20 times.
5. Dunk the slide into the Eosinophilic stain 15 to 20 times.
6. Dunk the slide into the Basophilic stain 15 to 20 times.
7. Rinse with tap water.
8. Allow to air dry.

Tape preps are also concentrated in infected areas, especially the paw and nonlumbar regions:

1. Using clear tape, take samples from multiple secreting infections.
2. There are two ways to stain the tape prep:
1. Using only the Basophilic stain, put two drops on a clean slide, one on each side, then affix the tape and remove the excess stain.
2. Secure only the ends of the tape to a clean slide, then place two small drops of Basophilic stain in between the slide and the tape, press down the tape and remove the excess. 

Direct skin impressions can be used instead of tape preps if lesions are present.

1. Using your slide, scrape the infected area.
2. Press the slide directly to the skin, making a smear.
3. Dunk the slide into the fixing agent 15 to 20 times.
4. Dunk the slide into the Eosinophilic stain 15 to 20 times.
5. Dunk the slide into the Basophilic stain 15 to 20 times.
6. Rinse with tap water.
7. Allow to air dry.

Now you’re ready for the microscope. For the skin scraping, you’ll want to examine every part of the slide at 10x resolution. For the wax smears and tape preps, you’ll want to do a 100x oil emulsion and look at 10 to 15 fields to get an average.

What you’re looking for (roll over to expand):

Demodex	Demodex Egg	Demodex Gatoi	Louse
Otodectes	Scabies	Scabies Eggs	Cheyletiella
Yeast	Yeast	Staph and Neutrophils	Staph with Streamed Neutrophils

Now, ask yourself:

1. What infections are present?
2. Why are they present?
3. Where are they present?
4. How do I treat them?
5. Who should I refer the dog owner to if needed?

Download this form to help in your examination:

 

Diff-Quik is a registered trademark of Dade Behring.