Page 1519 - Clinical Small Animal Internal Medicine

165 Parasitic Skin Diseases 1457

The mites complete their life cycle on the host but examining the sample with mineral oil increases the
VetBooks.ir mites and eggs attached to the hair shaft can contami- chances of finding the mite. However, none of these
diagnostic tests is 100% sensitive so a treatment trial may
nate the environment, creating a source for reinfestation.
The adult females can also live off the host for approxi-
mately 10 days. be necessary to confirm a presumptive diagnosis.
Therapy
History and Clinical Signs
Fortunately, cheyletiellosis typically responds well to
This mite infestation may result in varying levels of pru- therapy. Options include weekly applications of lime
ritus and severity of clinical signs. Any breed may be sulfur or amitraz (Mitaban) dips, or pyrethrin shampoos
affected, but an increased incidence in cocker spaniels and sprays for 3–4 treatments. However, amitraz and
and boxers has been anecdotally reported. The resultant especially permethrins are not generally recommended
dermatitis manifests as dry scales along the dorsum for cats due to drug sensitivities. Fipronil in the spray
(Figure 165.11). This often worsens over time with hair form every two weeks for 3–4 treatments or topical con-
loss and an increase in pruritus. Cats can also develop centrated solution every 30 days for three treatments are
miliary dermatitis. other options. Selamectin (Revolution) can be applied
monthly or every two weeks for 4–6 weeks. Ivermectin at
0.2–0.3 mg/kg can be given PO weekly for 3–6 treatments
Diagnosis
or by SC injection every 14 days for three treatments.
To diagnose Cheyletiella, material is collected from Doramectin is an option at 0.2–0.4 mg/kg SC every seven
affected areas by acetate tape impressions, flea comb- days for 4–6 weeks. One other treatment is milbemycin
ings, or superficial skin scrapes. This material can be oxime (Interceptor) given at 2 mg/kg PO weekly for 3–4
directly examined by visual inspection (often utilizing a doses. Because this is a highly contagious mite, all
magnifying glass) or using a microscope. If available, animals in the home should be treated.
evaluate material in a Petri dish in mineral oil utilizing a
dissecting microscope. Fecal examinations may also
reveal the mite as many pruritic animals will ingest the Lynxacarus radovsky
offending parasite in the process of licking, biting or
chewing the affected areas. Two other means of garner- Etiology/Pathophysiology
ing material for examination include a vacuum sample of
the affected area or performing a trichoscopy of affected This mite, otherwise known as the cat fur mite, is found
hairs. Some dermatologists find that scraping papules worldwide, typically in warm humid climates, such as in
(which are usually rare or absent) and microscopically Australia, Brazil, and Puerto Rico. In the United States, it
has been reported in Hawaii, Florida, and Texas. This
mite is specific to the cat, but has been found on a dog.
Cats acquire this mite through direct contact, but fomites
must also be considered.

History and Clinical Signs

Clinical signs include a dull, unkempt coat giving the hair
a “salt‐and‐pepper” appearance (Figure 165.12). Lesions
may include alopecia, papules, and crusting and are
typically present along the dorsum. Heavily infested cats
or those with a long‐term infestation can have exfolia-
tive lesions. Pruritus is not typically present and when
noted, a search for fleas or other external parasites is
warranted.

Diagnosis
Diagnosis of L. radovsky infestation is accomplished by
Figure 165.11 Cocker spaniel with cheyletiellosis showing identifying the mite with microscopy. Trichoscopy and
excessive scaling along the dorsum. tape impressions are the ideal diagnostic methods. The