Page 1048 - Problem-Based Feline Medicine

1040 PART 13 CAT WITH SKIN PROBLEMS

Pruritus is marked which may lead to self-inflicted
CAT FUR MITE (LYNXACARUS RADOVSKY)
trauma and quite severe excoriation which may then
become secondarily infected.
Classical signs
Less commonly the feet may also be involved.
● Dry, dull coat with hairs easily epilated.
● Excess scale and scurf.
● Tail-head, perineum and thighs affected.
Diagnosis
● Variable pruritus.
Diagnosis is based on clinical signs and finding the
mites. The mites are found in burrows in the superficial
Pathogenesis
epidermis. Superficial skin scrapes should be col-
lected: use a blunt scapel blade to remove the surface Lynxacarus radovsky is reported in northern Australia,
scale and crust. This material is transferred to a micro- USA and certain other tropical regions.
scope slide for examination.
All stages of the life cycle are found on the cat.
Biopsy of affected skin may reveal mites or eggs along
Adult and larval stages feed on skin debris and secre-
with non-specific superficial perivascular inflammation.
tions.
The mites generally do not burrow. Hence, lesions are
Differential diagnosis mainly found on the coat.
All conditions included in this section can be consid- Immunosuppression may be a factor.
ered as differential diagnoses.
Transmission is via direct contact, but the contagious
Flea allergic dermatitis is the single most common dif- nature of the mite is variable.
ferential for miliary dermatitis.
Clinical signs
Other differentials which warrant consideration include
food hypersensitivity, atopic dermatitis and various Typically there is scurfiness of the coat. The mites
ectoparasitic and microbial skin infections. appear as white flecks on the hairs, towards the tips
and are best visualized on cats with dark coat colors.

Treatment and prevention The coat is dull and dirty, and the hairs are frail and
easily epilated leading to patchy alopecia. In more
Lime-sulfur dips or shampoos (2.5%) are highly severe cases, a generalized maculopapular to exfolia-
effective. Treatment should be repeated every 10–20 tive dermatitis may develop.
days. Malathion dips (0.25–1.25%) and amitraz
washes (0.025%) are also effective. Lesions common along the lower back and per-
ineal/thigh areas.
Ivermectin (usually at dose levels of 200–300 μg/kg
SC although occasionally at dose levels as high as Pruritus is mild to absent, unless lesions develop on the
1000 μg/kg SC for 2–3 treatments) has been success- skin.
fully used, but is not licensed.
Diagnosis
Antibacterial cover and corticosteroids may be indicated.
In-contact animals should be treated if appropriate. Diagnosis is based on clinical signs and finding the
mites. Examination of affected hairs under the micro-
scope reveals adult mites attached to the hair.
Prognosis
Differential diagnosis
Prognosis is excellent with appropriate treatment. In
some cases, an immune response may develop leading All conditions included in this section can be consid-
to resolution of infection, even without treatment. ered as differential diagnoses.