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Flea Dermatosis
Fly Dermatosis
Myiasis
Helminths
Habronemiasis, Cutaneous
Hookworm Dermatosis
Onchocerciasis
Stephanofilariasis
Lice
Mites
Cheyletiellosis
Chorioptic Mange
Demodicosis
Notoedric mites
Otodectic Dermatosis
Psoroptic mites
- Occurs in cattle, sheep, horses, goats, rabbits and other animals
- Host-specific
- Psoroptes cuniculi in ear canals of rabbits, horses, goats and sheep
- P.equi at base of mane, tail and forelock in horses
- P.ovis in sheep (sheep scab)and cattle
- Thickened skin and dry scales and crusts
- Starts at withers and spreads due to self trauma
- Microscopically:
- Spongiotic, hyperplastic or exudative superficial perivascular dermatitis
- Eosinophils
Scabies
- Caused by Sarcoptes scabiei
- Highly contagious
- Mainly in pigs, dogs, also horses, cattle, sheep, goats and cats
- Intense pruritus due hypersensitivity to mites borrowing through stratum corneum
- Usually starts with external pinnae -> head -> neck -> generalised
- Grossly:
- Erythematous macules, papules, crusts
- If chronic -> lichenified, hairless
- Microscopically:
- Hyperplastic, spongiotic, superficial perivascular dermatitis
- Crusting, eosinophil infiltration
- Mites are not commonly seen, but eggs and feces may be found in stratumn corneum
Trombiculidiasis
- Harvest mite infestation (chiggers) - Trombicula sp.
- Form tunnels in epidermis by injecting saliva - eat digested tissue fluid
- Intense pruritus
- Grossly:
- Small, red papules or crusts
- Orange to red larvae
- On skin close to plants or the ground
- Microscopically:
- Hyperplastic, superficial perivascular dermatitis
- Eosinophils, mast cells
- Intraepidermal mites
Protozoa
- Cutaneous infection may become a part of systemic infection
- Mostly caused by Leishmania
- Transmitted by sandflies
- Occurs in dogs, cats and rodents (also humans)
- Grossly in dog:
- Generalised alopecia
- Silvery white scales
- Nodules and ulcers if more severe
- Mainly on muzzle, ears and eyes where flies feed
- Microscopically:
- Hyperkeratosis, parakeratosis, crusts
- Granulomatous nodules in dermis
- Macrophages, some lymphocytes and plasma cells - periadnexal pattern, may affect sebaceous glands
- Organisms may be found extra or intracellularly
Ticks
- Local reaction depends on host hypersensitivity and tick's secretions
- Grossly:
- Focal erosions, erythema, crusted ulcers, sometimes alopecia and nodules
- Microscopically:
- Epidermal and dermal necrosis
- Perivascular of diffuse inflammation and necrotic margins
- Eosinophils, macrophages and lymphocytes in exudate
- May form granulomas containing collagenous fibres and lymphoid follicles within dermis