Page 1521 - Clinical Small Animal Internal Medicine

165 Parasitic Skin Diseases 1459

Diagnosis of the mite or the nit (egg). Microscopy can be utilized to
VetBooks.ir Finding the mite is best achieved by performing skin view acetate tape impressions of hair and scale.

scrapings. Mites may also be visualized microscopically
on samples collected with cellophane tape impressions. Therapy
Treatment should target the affected animals as well as
Therapy those in contact. Clipping of matted hairs is recom-
mended. Topical sprays and soaks such as lime sulfur can
These mites generally respond well to almost all parasiti- be utilized twice two weeks apart. However, most insec-
cidal treatments. It is also recommended to treat the ticidal therapies are efficacious. These include but are not
surrounding premises to prevent reinfestation.
limited to ivermectin at 0.2 mg/kg PO or SC twice two
weeks apart, selamectin (Revolution) every two weeks for
2–4 treatments, or spot‐on fipronil (Frontline®) or spray
Pediculosis every two weeks. One application of fipronil or selamec-
tin may work as well for chewing lice. Doramectin can
Etiology/Pathophysiology also be used at 0.2–0.4 mg/kg SC weekly for 3–4 weeks.
Imidacloprid (Advantage) spot‐on alone for one applica-
Pediculosis refers to a dermatitis caused by lice. Two
types affect dogs, Anoplura, or sucking lice, and tion to treat chewing or sucking lice or the combination
Mallophaga, or chewing lice. Linognathus setosus is the with moxidectin (Advantage Multi) applied topically
sucking louse of dogs and Trichodectes canis the chewing once for chewing lice should be effective. Fluralaner
louse. Cats are parasitized only with a chewing louse, (Bravecto) given once PO has been shown to eliminate
Felicola subrostratus. The eggs are deposited on the hairs Linognathus setosus. Appropriate supportive care may be
of the host. The lice typically stay on one host but can be required for anemic animals. Premises should be treated
transmitted by close contact. They are species specific. as lice can survive 1–2 days off the host.
The chewing lice survive primarily on epidermal debris
and hair but some species also take blood. The canine
chewing louse may carry Dipylidium caninum, or tape- Trombiculosis
worms. Sucking lice solely feed on the blood of the host
and can result in severe anemia. History and Clinical Signs
Trombiculosis is a dermatitis caused by chigger mites.
History and Clinical Signs The larval forms can cause infestation of dogs and cats.
Eutrombicula alfreddugesi, a mite found in the south-
Pediculosis is relatively uncommon, but more likely to be east and south central United States, and Neotrombicula
noted in young and uncared‐for animals. Chewing lice autumnalis, a mite more commonly found in Europe, are
on the dog typically affect the dorsum, head, and tail and notably orange‐red in coloration (Figure 165.15). They
can cause severe pruritus. In the cat, the face, ears, and typically affect patients in late summer and fall. The
back are most commonly affected. Lesions on the dog larval forms attach to the skin.
typically consist of trauma‐induced alopecia, seborrhea, Lesions often occur in body regions that contact the
and excoriations. Papules and crusts may also be present. ground. However, in cats they are most commonly noted
Cats can present with no clinical signs or have intense around the eyes, mouth, and base of the pinnae. The
pruritus. The coat may be matted with scale, crust, and larvae pierce the skin and produce pruritic papules and
alopecia. Sucking lice are primarily present on the pin- crusts. Scaling and alopecia may also be present. Some
nae and dorsum, and can result in weakness from the animals are asymptomatic.
ensuing anemia. Pruritus with resultant excoriations and Walchia americana is a chigger mite that has been
alopecia may also occur. reported in cats. It has been found in the southwestern
and eastern United States. These mites preferentially
affect the ventrum, dorsum, and ears but have been
Diagnosis
noted on the medial legs and interdigital spaces. Reported
Lice can be distinguished based on the morphology of lesions include nodules, papules, and wheals with scales
the head and associated mouthparts. Sucking lice have and yellow exudate. Swollen paws and cracked claws
an elongated, narrow head, whereas chewing lice have a have been noted.
broader head with mouthparts adapted for chewing. Straelensia cynotis has been noted on dogs in some
They can sometimes be found with direct visualization European countries. It too causes infestation primarily in