TEST Demodex mites are considered to be a normal part of the cutaneous microfauna in the dog and are transmitted from the bitch to the pups during the first days of life.
Species which are pathogenic to dogs include:
The parasite normally resides within the hair follicles of dogs and secondary bacterial infections do occur. The role of Staphylocoocus pseudintermedius as a secondary contaminant is an important consideration. No evidence of Wolbachia spp endosymbionts has been detected with this parasite as is seen with Dirofilaria spp.
Clinically affected dogs with localized demodicosis present with alopecia, dermatitis, comedones, follicular papules and pustules, scaling, and crusting. Pruritus is uncommon unless bacterial infection is involved.
In immunocompromised patients, generalized demodicosis occurs due to premature apoptosis of peripheral leucocytes. This is thought to be the mechanism underlying the immunosuppression observed with generalized demodicosis.
Diagnosis is made by deep skin scrapings, although mite numbers are often small. Skin cultures are essential, because dermatophytosis such as Microsporum spp and yeast such as Malassezia spp often occur concomitantly with this disease.
Chlorhexidine and benzoyl peroxide shampoo weekly washes are indicated as antibiotic guidelines recommend to limit the use of broad spectrum antiobiotics in favor of topical antiseptics.
Miticidal drugs are usually indicated, such as:
- Ivermectin at 600 μg/kg every 24 hours orally for 6 - 8 weeks or until negative skin scrapings is achieved.
- Milbemycin orally at 1 - 2 mg/kg daily
- Moxidectin at 0.3 mg/kg after daily gradual dose increases from 0.05mg/kg
- Doramectin orally or subcutaneously at 0.6 mg/kg
It is recommend to extend the treatment to beyond negative scrapings. The prognosis is good for most dogs, and better in juvenile than adult dogs, as juvenile dogs generally don’t have underlying diseases.
Prognosis of generalized demodicosis in older dogs is unpredictable because of its potential relationship with systemic disease. Some cases spontaneously resolve.
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