Deep Pyoderma Associated with Demodicosis and Actinic Dermatitis in Dog

Abstract

Background: Actinic Dermatitis (AD) is mainly caused by prolonged exposure to solar and ultraviolet radiation and mainly affects short-haired dogs with poorly pigmented or depigmented skin, leading to immunological and systemic changes. Deep pyoderma consists of a skin barrier dysfunction due to changes in the immune system or metabolism, occurring in cases of severe systemic immunosuppression or associated with demodicosis. Demodectic mange is caused by excessive multiplication of host-specific commensal mites in hair follicles and sebaceous glands. This study aims to report the case of a Pit Bull male dog affected by deep pyoderma associated with demodicosis and actinic dermatitis. 

Case: A 3-year-and-6-month-old male Pit Bull dog with a history of actinic dermatitis, 2 years ago, was submitted for clinical evaluation at the Veterinary School Clinic (CVE) of the Santa Catarina Federal University (UFSC), Curitibanos “campus”. The guardian complained about new skin lesions that were not improving, and the patient showed more apathy. On dermatological examination, meliceric abrasions and crusts, the presence of erythema in the hocks, ears, face, and inguinal region, alopecia, papules, and pustules in the abdomen and face, and edema in the left pelvic limb with marked sensitivity were noted, all lesions distributed asymmetrically. The patient was referred for collection of materials for parasitological examination by deep skin scraping, bacteriological culture (swab) of the lesions of the left pelvic limb. The parasitological result was positive for Demodex canis and the culture isolated Staphylococcus sp. The antimicrobial susceptibility test results indicated sensitivity to Clavulanic Acid associated to Amoxicillin and Cephalexin, and resistance to Ciprofloxacin, Clindamycin, Enrofloxacin and Sulfazotrim. The diagnosis was deep pyoderma associated to actinic dermatitis and demodicosis. We opted for treatment with Cephalexin at a dose of 20 mg/kg BID, Prednisone at 0.78 mg/kg BID, and topical use of mupirocin and sunscreen, in addition to the prescription of the active ingredient sarolaner or fluralaner every 30 or 90 days, respectively. After the beginning of treatment, the patient showed significant improvement in clinical signs and continues to be treated for actinic dermatitis.

Discussion: AD tends to occur in light-coated Pit Bull dogs, with lesions on poorly pigmented skin surfaces, such as the ventral region of the abdomen, limbs, and face, due to the absence of photoprotective factors. The patient in question was a Pit Bull with a white and black coat, already diagnosed with AD 2 years ago. Prolonged exposure to solar or ultraviolet radiation can lead to local or systemic immunological changes, leading to immunosuppression and facilitating the proliferation of pathogenic microorganisms, worsening the clinical picture. In this case, the animal had dermatological changes indicating the presence of concomitant diseases to AD, the primary being deep pyoderma, probably secondary to demodicosis. The definitive diagnosis was made from complementary examinations, which are indispensable for the conclusion and effective therapy. In conclusion, despite the common occurrence of demodicosis in the clinical routine and the secondary appearance of pyoderma, the event in conjunction with AD is scarcely reported, requiring the investigation of underlying diseases that occur with immunosuppression.

Keywords: solar dermatitis, deep pyoderma, demodectic mange, canine.

Título: Pioderma profunda associada a Demodicose e a Dermatite Actínica em um cão

Descritores: dermatite solar, pioderma profunda, sarna demodécica, canino.