DERMATOLOGY
History
Figure 4: Cutaneous epitheliotropic lymphoma in various canine patients
Signalment and clinical signs
should be noted and history recorded:
• Degree, location, and seasonality of pruritus
• Duration and progression of
lesions
• Previous treatments and response
• Dietary history
Physical Examination
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Cutaneous examination (eg,
of the footpads, interdigital
spaces, and nasal planum)
should be completed.
Otoscopic and ophthalmic
examinations should be performed.
The oral cavity, mucous
membranes, and mucocutaneous junctions should be
examined.
Lymphadenopathy should be
assessed and lymph nodes
palpated.
as (~100 hairs per sample) can be plucked and examined
with mineral oil and a coverslip.1
Diagnosis
Definitive Diagnosis
• Definitive diagnosis is achieved via history, examination, and appropriate diagnostics
• Secondary infections should be resolved, as they
can confound clinical and histopathologic features of the primary cause.
• Histopathology is required for diagnosis of immune-mediated disease, superficial necrolytic
dermatitis, zinc-responsive dermatitis (Figure 3)
and cutaneous epitheliotropic lymphoma (Figure
4)
• Patients with nonseasonal perioral pruritus may
require an 8-week prescription or home-cooked
elimination diet to differentiate atopic dermatitis
(Figure 5) from cutaneous adverse food reaction
(CAFR).
Cytology
•
Acetate tape preparation (only for dry lesions)
and impression smear of exudates should be
performed to assess for bacteria, Malassezia spp,
and presence of acantholytic keratinocytes.
Cultures
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Elimination Diet Trial
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Issue 04 | JULY 2015 | 28
Vesiculobullous presentations (Figure 7) and lesions that
remain after resolution of secondary infection should
undergo biopsy.
Multiple lesions representing all stages of disease should
be sampled.
Additional Diagnostics
•
Deep skin scrape
Deep skin scrape or pluck for Demodex spp (Figure
6) should be performed in all cases.
• If patient compliance impedes the performance
of a deep skin scrape, several representative are-
A strict novel or hydrolyzed diet or home-cooked novel
diet should be prescribed for a minimum of 8 weeks to
differentiate CAFR from nonseasonal atopic dermatitis.
Diet should be rechallenged to confirm the diagnosis.
Histopathology
Fine-needle Aspiration
Nodules and enlarged lymph nodes should be aspirated.
Dermatophyte culture is indicated if lesions are consistent (see Causes of Perioral Dermatitis) and secondary
infection and Demodex spp have been ruled out.
Bacterial culture is indicated if clinical and cytologic response to antimicrobial therapy is lacking.
Culture nodular or ulcerative lesions if bacteria are
found on cytology; culture superficial lesions if intracellular rods are found.
•
Serum biochemistry profile and abdominal ultrasonography are recommended to support diagnosis of superficial necrolytic dermatitis.
CBC, serum biochemistry pro