Skin Congenital and Hereditary - Pathology

Hypertrichosis

• Increased hair growth
• Both congenital or hereditary
• In sheep may be caused by Border Disease virus
• Microscopically:
  • Enlarged primary follicles and wool fibres
• Also accociated with maternal hyperthermia

Ichthyosis

• Inherited cutaneous disease
• Occurs in dogs and cattle
• Grossly:
  • Thickened skin due to hyperkeratosis
  • May crack resembling fish scales
• Increased adherence of keratocytes preventing normal desquamation
• In cattle occurs in two forms:
  • Ichthiosis fetalis - fatal, stillborn calves or die within days of birth
  • Ichthiosis congenita - folded and thickened skin, fissures and partial alopecia

Porcine Juvenile Pustular Psoriasiform Dermatitis

• Also called Pityriasis Rosea
• Occurs in pigs
• Symmetric lesions on the abdomen, loin and medial thigh
• Start as small papules covered by brown crusts
• -> lesions join and spread -> umbilicated plaques containing white centres with erythematous and scaly borders
• Similar to dermatophytosis
• Histologically:
  • Epidermal hyperplasia, parakeratosis, epidermal pustules and superficial perivascular dermatitis
• For more detail see Porcine Juvenile Pustular Psoriasiform Dermatitis

Zinc-related disorders

• Occurs in Bullterriers and calves
• Resolves with zinc supplementation in calves but not dogs
• In dogs:
  • Fatal acrodermatitis
  • Lesions start between digits and on foot pads -> severe interdigital pyoderma -> paronychia and hyperkeratosis of pads
  • May also occur on pinnae, elbows, muzzle, hocks or become generalised with crusting, ulceration and secondary pyoderma
  • Histologically:
    • Hyperkeratosis and bacterial pustular dermatitis