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Diisseeaasseess ooff tthhee SSkkiinn
Dermatophytosis
Dermatophytosis is an infection of keratinized tissue (skin,
hair, and claws) by one of the three genera of fungi
Epidermophyton,
Microsporum,
and
Trichophyton.
Microsporum canis is the most common infection.
Clinical Symptoms
Kittens are most commonly affected. Lesions consist of focal
alopecia, scaling, and crusting; most infections occur around
the ears and face or on the extremities. The hair becomes
brittle. Feline miliary dermatitis with pruritis is occasionally
observed. In dogs the lesions include alopecia, scaly patches
with broken hairs and dogs may also develop regional or
generalized folliculitis with papules and pustules.
Diagnosis
Direct smear, culture and clinical signs are sufficient; the
Wood's lamp is useful in establishing a tentative diagnosis.
Treatment and Prevention
Management
Non-drug treatment
 Dermatophytosis in dogs and shorthaired cats is usually
self-limiting, but resolution can be hastened by treatment.
Drug treatment
First Line:
 Miconazole 1% solution, q 1-2 h, then q 3-4 h after 34 days.
In chronic or severe cases use
 Griseofulvin in dogs 25-100 mg/kg once daily or
divided in two doses; in cats 25-50 mg/kg daily, also
divided doses. Treatment should continue for 2-4 wk
past clinical cure. S/E, C/I, D/F, D/I, see page 296.
Alternative:
 Ketoconazole 10 mg/kg, continue for 2-4 wk after
clinical cure. S/E, C/I, D/F, D/I, see page 296
or
 Itraconazole at 5 mg/kg, daily should be continued for
2-4 wk past clinical cure. S/E, C/I, D/F, D/I, see page
296
Prophylaxis: Avoid contact with infected pets.
Public health significance: It is zoonotic and one has to
take care during handling of infected dogs.
Fleas and Flea Allergy Dermatitis
Fleas have piercing mouthparts that they insert into the skin
of their host to feed on blood. Species commonly infest dogs
and cats: Ctenocephalides felis (the cat flea), C. canis (the
dog flea), Pulex simulans (a flea of small mammals), and
Echidnophaga gallinacea (the poultry sticktight flea).
However, by far the most prevalent flea on dogs and cats is
C. felis.
Fleas cause flea allergy dermatitis, are vectors of typhus-like
rickettsiae and intermediate host for filarid and cestode
parasites.
Clinical Symptoms
In Flea allergy dermatitis (FAD) pruritus is observed. In
dogs, papulocrustous lesions distributed on the lower back,
tailhead, and posterior and inner thighs. Dogs may be
particularly sensitive in the flanks, caudal and medial thighs,
ventral abdomen, lower back, neck, and ears. Affected dogs
are likely to be restless and uncomfortable, spending much
time scratching, licking, rubbing, chewing, and even nibbling
at the skin. Hair may be stained brown from the licking and
is often broken off. Common secondary lesions include areas
of alopecia, erythema, hyperpigmented skin, scaling,
papules, and broken papules covered with reddish brown
crusts.
In cats, papule, which often becomes crusted is observed on
the back, neck, and face. Pruritus may be severe, evidenced
by repeated licking, scratching, and chewing. Cats with FAD
can have alopecia, facial dermatitis, exfoliative dermatitis,
and “racing stripe” or dorsal dermatitis.
Diagnosis
History, clinical signs, presence of fleas or flea excrement,
results of intradermal testing.
Treatment and Prevention
Management
Drug treatment:
First line:
 Microencapsulated chlorpyrifos (see accompanying insert
for application).
 Permethrin (see accompanying insert for application).
Al ternative
 Non-encapsulated chlorpyrifos (see accompanying leaflet
for application).
Second line:
 Organophosphates, carbamates, pyrethroids, for dosage,
S/E, C/I, D/F, D/I, see External Parasites of Cattle:
Acaricides.
For seconday infection Antibiotics; for dosage, S/E, C/I, D/F, D/I, see page 304.
plus
 Prednisolone 0.5-1.0 mg/kg daily, tapering the dosage and
using alternate-day therapy until the lowest dose possible
that still controls the pruritus. S/E, C/I, D/I and D/F see
page 306.
Note: Anti-inflammatory therapy should never be used as a
substitute for flea control. Fleas are vectors for zoonotic
diseases and control should be implemented.