Vet360 Vol 3 Issue 04 August 2016 - Page 34

DERMATOLOGY HOOKWORM DERMATITIS: Hookworm dermatitis is caused by Ancylostoma caninum where infected larvae, present in soil or mud, in poorly kept kennels or highly contaminated environments, penetrate the skin and burrow into the hair follicles of thin skinned areas (axillae/inguinal regions/ventral abdomen), the foot pads and interdigital areas where they continue their life cycle. Young animals living in groups in unhygienic conditions and hunting dogs are highly predisposed. The thin skinned areas commonly have papules, crusts and excoriations and the foot pads are usually oedematous, thickened and ulcerated. Paronychia and deformed nails may be present in chronic cases. Systemic signs such as diarrhoea, anaemia and weight loss are often present. Diagnosis is made with faecal flotation. Histopathology usually reveals eosinophilic perivascular dermatitis and sometimes larvae can be found. Prognosis is good if the affected dog is dewormed and removed from the contaminated environment. DEMODICOSIS: Demodicosis is a differential diagnosis for every case of pododermatitis. Usually this is a generalised skin disease that can involve the paws but rarely if may affect the paws only and in very rare cases the foot pads as well. The feet become inflamed and may show hair loss, redness, swelling, crusting and scaling. The foot pads become crusty and thickened. The diagnosis can be made by microscopic examination of hair plucks or skin scrapings from the paws, but biopsy and histopathology are required in most cases. Treatment with systemic and topical parasiticides for many weeks to months is usually required for successful management. Secondary bacterial infections are common and should be treated. HARD PAD DISEASE: There are 2 different types of hard pad disease: The first type is a crusting, thickened foot pad and is seen with e.g. pemphigus foliaceous, zinc responsive dermatosis, distemper infections and necrolytic migratory erythema. These foot pads may be painful and cause lameness. Most commonly these cases will have other accompanying skin lesions and systemic signs, although rare cases of pemphigus foliaceus may present with foot pad lesions only. Biopsies are the most helpful diagnostic procedure. Treatment will depend on the underlying cause. The second type is a foot pad with excessive fronds of normal appearing keratin. This is most obvious at the margins of the pads and represents overgrowth of the normal keratin mounds of the pads. Inflammation and exudate are not present. Lameness and pain are usually not detected. This condition appears more as if the pads grow abnormally fast and do not desquamate. PEMPHIGUS FOLIACEUS: Pemphigus foliaceus is the most common of the pemphigus complex. It is characterized by a scaling, crusting and pustular dermatitis that usually affects the face, ear pinnae and foot pads. Some cases may become generalized. The foot pads are usually swollen and hyperkeratotic with scaling, crusting, hardening and fissuring. In severe cases there may be pustule formation, greenish/yellowish discoloration and significant epithelial loss of the foot pads. Cytological examination of the purulent material will reveal large numbers of neutrophils and/or eosinophils and acantholytic keratinocytes which are highly suggestive of pemphigus foliaceus. Bacteria are usually not present on cytology of intact pustules, but may contaminate ruptured lesions. There are usually not systemic signs, but lesions may be painful. The diagnosis is supported by cytology and should in all cases be confirmed by histopathology. This condition is treated with immunosuppressive dosages of prednisolone with or without azathioprine. Topical corticosteroid therapy may be useful for stubborn localised lesions. Pemphigus foliaceus affecting the footpad (Photo: Dr Heidi Schroeder) CUTANEOUS DRUG REACTIONS: Cutaneous drug reactions are adverse reactions following systemic and topical drug administration. The pathogenesis is complicated involving both immunological and nonimmunological reactions. All types of hypersensitivity reactions have been reported. Clinical signs are highly variable. In most cases the clinical signs are mild (urticaria, erythroderma), but can also be very serious and sometimes fat [ \][XH][YܛYKX\Y\X[Xܛ\\[YZ[XY[\Y\XX]\K\\\[]\[\\[ۜXX^H[YB\[\\]Y\\[ۜ[[\ۈ\[\\›وHK[Y[HY[YX\[Y]]HY[\ܝY]\HXXX[ۜ[YH[XX\X[ [ۘ[ZY\\[ܚ[K[Y[[ ]Xۘ^Kܚ\[ٝ[[H[[\\\]XY ]\YX[[YX[KX[\X[Yܛ[ۙ\[[]Z[\\˂\H\ٝ[HY\[و H H^\YܙH[X[YۜX[Y\ [[\\\۝[X][ۈقHYYX][ۈ[X]Y[وXۙ\H[X[ۜY\[ \[[\][ۈوH[\[ۜˈYH\\\]Z\H[ܙHYܙ\]HX]Y[KˈXܝXY[\[[][\\]BYˈY\HYX[\\܈ H YZY\\۝[X][ۈوHٙ[[YYX][ۋ] ͌\YH UQT M U ͌UQT Mܚ[˚[  M ̍H LN B