Page 109 - JSOM Summer 2018

• Onset and duration of clinical signs (e.g., lesion appear- more than one Malassezia organism supports a secondary
ance, self-directed behavior such as licking, chewing, yeast infection.
and scratching at location of interest)
• Known, preexisting allergic diseases (e.g., atopy, food Deep skin scrapings
allergies). For previously diagnosed conditions, inquire Skin scraping samples the epidermis (full thickness) and the
about the prescribed treatment plan (e.g., medications, contents of the hair follicles. It is commonly used for ruling
diet). Are these treatments or diets provided as prescribed? out mite infestations (e.g., Demodex) in dogs. The presence of
• Known, preexisting ear infections or anal gland dis- more than one Demodex mite (live or dead), as well as frag-
eases. Are there associated prescribed treatments? Are ments of mites or mite eggs, confirms demodicosis (Box 2).
these treatments administered as prescribed?
• Dietary history. What is the OpK9’s normal diet (e.g., BOX 2 Procedure for Deep Skin Scraping
brand, dry kibble or canned, prescription diet)? Any Equipment:
recent change in diet? Any “non-dog food” (e.g., table • No. 10 scalpel blade, sterile or stainless steel microspatula
scraps) items fed? • Microscope slide and cover slips
• Current preventive plan for treating ectoparasites (i.e., • Mineral oil
fleas, ticks). When was the OpK9 last treated and what Technique: 7
was the treatment? Any topical treatments? Any recent 1. Select a 1- to 2-inch hairless or clipped area within the active
lesion.
change in the treatment products or medications used? 2. Apply 1 or 2 drops of mineral oil on the area to be sampled and
• Frequency of bathing, swimming, and grooming. What on the scalpel blade. This facilitates collection of mites during the
products are used to bathe the OpK9? scrape and visualization of mites during microscopic examination.
• Known recent dermal exposure to topical medications 3. Hold a No. 10 scalpel blade (or similar instrument, such as a
small metal spatula) perpendicular (i.e., at a right angle) to the
or accidental exposure to compounds or chemicals skin and scrape vigorously in the direction of hair growth. Scrape
at least six or seven times in the same direction.
Physical Examination Findings Helpful Hints:
Hot spots are typically more extensive than they initially ap- • Demodex spp. mites are often located deep within the hair
pear. Often, a significant portion of the lesion is covered by follicles; therefore, it is sometimes difficult to collect them during
the overlying hair coat. Performing a thorough assessment and a skin scrape. To facilitate the success of extruding mites from
determining the extent of the lesion require careful clipping of within hair follicles, consider:
o Squeezing or pinching the skin before performing the skin
the hair coat around and over the entire lesion. If anatomically scrape
feasible, clip an additional 1- to 2-inch margin of normal area o Applying enough pressure with the scalpel blade to cause
extending beyond the edges of the lesion. Common postclip- capillary bleeding
ping observations include erosions, excoriations, ulcerations, • To prevent unnecessary injury to the dog, dull the blade by
and peripheral erythematous papules (satellite lesions). 5 repeatedly scraping the blade’s edge on a hard surface before
scraping the skin.
4. With the blade or spatula, scoop the collected material and oil
Note: Hot spots are intensely pruritic and often very irritating from the skin and place on a glass microscope side. Place a cover
and painful; therefore, many OpK9s require procedural seda- slip on top and examine under microscope.
tion to allow clipping and cleaning of the lesion.
Skin biopsy and histopathology
Diagnostic Tests Biopsy specimens for histopathologic evaluation are required
When resources are available, laboratory testing should consist to definitively differentiate pyotraumatic dermatitis from deep
of, at a minimum, complete blood cell count, serum chemis- pyoderma or pyotraumatic folliculitis/furunculosis. Histo-
try profile, and urinalysis, along with dermatologic diagnostics pathology is necessary to guide therapy when dealing with
(i.e., skin cytology, skin scrapings, trichogram, dermatophyte chronic and relapsing cases. Findings associated with pyo-
culture, skin biopsy specimen with histologic examination). In traumatic dermatitis include superficial dermal inflammation,
conjunction with obtaining a history and performing a thor- epidermal erosion, necrosis or ulceration, epidermal crusting
ough head-to-tail examination, findings from a skin cytologic with evidence of coccoid bacteria colonization, and superfi-
evaluation and scraping are typically sufficient to make a diag- cial dermal edema. Neutrophilic infiltrates predominate, with
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nosis of pyotraumatic dermatitis and start an initial treatment acute superficial lesions; a small proportion of cases also con-
plan. Skin biopsies to obtain specimens for histopathology, tain eosinophilic infiltrates. A mild to moderate lymphohis-
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dermatophyte and bacterial cultures, and work-ups for allergic tiocytic inflammation is commonly observed adjacent to the
skin conditions (e.g., atopic dermatitis, food allergies) usually ulcerated or eroded areas.
are pursued when faced with relapsing and chronic conditions. 1
Treatment
Skin cytology
Impression smears are useful when conducting skin cytology In many cases, early and appropriate treatment results in a rapid
of samples from moist exudative wounds, whereas an acetate resolution of clinical signs. Because pyotraumatic dermatitis
tape preparation is better indicated when sampling from a dry, occurs secondary to another underlying medical or behavioral
flaky lesion. Cytologic findings consistent with pyotraumatic condition, it is necessary to identify and appropriately treat the
dermatitis reveal a mild to severe neutrophilic (suppurative) in- primary underlying cause (Box 1) to achieve full clinical res-
flammation. Extracellular bacteria with or without evidence of olution and prevent relapse. Appropriate treatments for each
neutrophilic inflammation often indicate bacterial overgrowth potential primary cause is beyond the scope of this article. For
or surface bacteria, but their presence does not completely primary self-directed behavioral issues, attempt to remove and/
rule out pyoderma. The presence of intracellular bacteria and or minimize any known or suspected social or environmental
inflammatory cells confirms a bacterial pyoderma. Observing stressors that foster anxiety, frustration and/or conflict.

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