Small Animal Dermatology, 3rd edition

300 DISEASES/DISORDERS

 Acetate tape preps may be used to identifyD. cornei(short-bodiedD. canis: dog) and

D. gatoi.

 Otic swabs will identifyDemodexas a cause of otitis externa.

 Fecal exams may be helpful in cats due to the grooming behavior.

 Cutaneous biopsy: may be needed when lesions are chronic, granulomatous, and

fibrotic (especially on the paw); mural folliculitis, nodular dermatitis, suppurative

folliculitis and furunculosis; follicles filled with mites and keratinaceous debris; use-

ful in the shar-pei due to difficulty obtaining mites in scrapings.

THERAPEUTICS

 Localized: conservative; most cases (90%) resolve spontaneously with no treatment.

 Evaluate the general health status of dogs/cats (serum chemistry, CBC, FeLV/FIV, uri-

nalysis, heartworm testing).

 Generalized (adult dog): frequent management problem due to expense and frustra-

tion with the chronicity; many cases are medically controlled, not cured.

 Antibiotic therapy in conjunction with adjunctive topical therapy (antibacterial

shampoo/spray) frequently warranted to control secondary infections.

 Continue treatment for at least 1 month past a clinical cure and negative skin scraping.

 Regular monitoring with scrapings during the year following treatment is advisable.

Drugs of Choice: Dogs

 Amitraz:
FDA-approved for treating dogs over 4 months of age
Formamidine: inhibits monoamine oxidase and prostaglandin synthesis; an

alpha 2-adrenergic agonist

Small dogs may exhibit marked lethargy 12–24 hours after application

Patients with respiratory disease or diabetes should not be treated with amitraz

Adverse reactions include depression, vomiting, diarrhea, ataxia, polyphagia,

and polydipsia

Dilute as directed on the label (250 ppm); apply to the entire patient weekly to

every other week until resolution of clinical signs and no mites are found on

skin scrapings; do not rinse off; allow to air-dry

Continue rinses for at least 1 month following negative skin scrapings

Apply a benzoyl peroxide shampoo before application as a bactericidal therapy

and to increase exposure of the mites to the miticide

Efficacy is proportional to the frequency of administration and the concentration

of the rinse

Mix with mineral oil (3 mL amitraz to 30 mL mineral oil) for application to focal

areas, such as pododemodicosis

9% amitraz collar: success has not been established, although there are positive

anecdotal reports; not recommended