pruritus'

• Pruritus is the unpleasant sensation that elicits the desire or reflex to scratch (rub, lick and chew). It is the most common dermatological presentation in dogs and the 2nd most common in cats.
• More than one feline reaction pattern may be present and if so this indicates an allergy (FFA) or fleas (FAD) or feline atopic skin syndrome (FASS). The reaction patterns include…

  • Self-induced alopecia (SIA)
  • Face, head and neck pruritus (FHN)
  • Miliary dermatitis (MD)
  • Eosinophilic granuloma complex (EGC)
• most cases of Face, head and neck pruritus (FHN)are due to ectoparasites, especially fleas
• • An eosinophilic granuloma is a well-demarcated, solid, raised, yellow to pink plaques/nodules +/-eroded or ulcerated surface +/-crust
  • Any site but especially caudal thighs (linear presentation), oral cavity, feet, chin
• • Eosinophilic plaque is a raised, flat-topped erythematous plaque. This is usually ulcerated/eroded and pruritic on the ventral abdomen/caudal thigh
  • Secondary bacterial infection is common

  
• • Indolent ulcer (rodent ulcer) is an erosive/ulcerated lesion on the mucocutaneous junction of the upper lips. This can be unilateral/bilateral and is rarely painful or pruritic.
  • Possibly associated with pyoderma and a FB reaction to intradermal keratin –caused by licking?

  
• flea allergic dermatitis, feline good allergy and feline atopic skin syndrome should be considered with any of the feline reaction patterns
• There is a potential for co-existence which causes a summation of pruritus. It may be hard to control one of the causes e.g., environmental atopy but you can improve the patients QOL by reducing the load and combating the other causes to the summation.
• Lesions affecting caudal and dorsal regions in dog mean that FAD should be the top differential.

  
• Epidermal collarettes and crusts are usually due to superficial pyoderma, occasionally PF.
• name the lesion

  epidermal collarettes

  
• Pustules are usually caused by a superficial pyoderma (staphylococcal folliculitis). Uncommonly it can be due to demodicosis, dermatophytosis, pemphigus foliaceus (PF). Rarely, it is caused by other sterile pustular diseases
• Endocrinopathies may present as pruritus due to the secondary microbial infection caused by the immunocompromised state
• Investigations for fleas, Sarcoptes, Cheyletiella has low sensitivity so don’t believe a negative test. Perform a thorough treatment trial if not on a good (ideally isoxazoline) regime already
• You suspect a 2yo French bulldog with generalised pruritus to be suffering from canine atopic dermatitis. You have found no evidence of microbes or ectoparasites on investigation. What is your next step?

  Treat this dog and in-contacts with an isooxazoline, and use an environmental flea spray