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Feline idiopathic ulcerative dermatitis

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01 December 2015, at 12:00am

David Grant continues the series of dermatology briefs.

FELINE idiopathic ulcerative dermatitis is a rare skin disease seen exclusively in cats.

Clinical features

  • The lesion normally occurs on the dorsal midline of the caudal neck or between the scapulae. 
  • Non-healing, deep ulcer, abundant crusts and a border of non-healing skin.
  • Pain and pruritus are variable. The cat may intermittently ferociously attack the lesion. 
  • Mild peripheral lymphadenopathy may be present.

Differential diagnosis

  • Injection reactions. 
  • Foreign body reactions. 
  • Bacterial, fungal or viral infection. 
  • Demodex gatoi
  • Trauma. 
  • Burn. 
  • Hypersensitivity – flea,food atopy (Hnilica, 2011).

Diagnosis

  • Physical examination. 
  • The lesion and its site are suggestive. There may be a history of recent injection/ vaccination/spot-on application in this site. However, cases have been seen with no such history. 
  • Investigate and rule out differentials. 
  • Biopsy. Extensive epidermal ulceration. Chronic cases may show a sub-epidermal band of dermal fibrosis as described in the original report of the condition (Scott, 1990).

Treatment

  • Investigate and rule out differential diagnoses. 
  • It has been suggested that a lime sulphur trial to eliminate Demodex gatoi should be considered as this mite may be difficult to find (Hnilica, 2011).
  • Before attempting medical therapy it is necessary to apply bandages and a covering dressing to the area. Bandaging of the feet may also be useful. The object is to facilitate healing of the area. In typical cases this will be at least a month. 
  • Once healing has been achieved the dressings can be removed and the cat monitored. Unfortunately this is often followed by a recurrence of the severe self-trauma that caused the initial lesion. In these cases, once healing is re-established medical therapy is tried.
  • Systemic glucocorticoids may be effective. Prednisolone at a dose of 4mg/kg every 24 hours initially with gradual tapering. It is possible that lesions will be refractory to this therapy even with the use of more potent glucocorticoids such as dexamethasone or triamcinolone.
  • Wide surgical excision may be attempted. This is often unsuccessful.
  • The prognosis is therefore guarded because underlying factors are poorly understood and even with apparently successful healing relapse may occur rapidly once protective bandages are removed.
  • A review of the history in a specific case suggested that the underlying stimulus to the severe self trauma was intermittent, occurring at 6am and 6pm. In the interim the cat would not scratch at the lesion.
  • A veterinary neurologist was therefore consulted with the result that several anti-epileptic drugs were trialled. One of these, topiramate, a drug used in human medicine and also for refractory epilepsy in cats (with informed consent) resulted in an immediate improvement. 
  • The dose was 5mg/kg every 12 hours and the improvement has been maintained over a two-year follow-up. This has led to the suggestion that the disease may be a neuropathic disorder (Grant and Rusbridge, 2014).

References and further reading

Grant, D. I. and Rusbridge, C. (2014) Topiramate in the management of Feline Idiopathic Ulcerative Dermatitis in a two-year-old cat. Veterinary Dermatology 25 (3): 326-330. 

Hnilica, K. (2011) In: Small Animal Dermatology – A Color Atlas and Therapeutic Guide, 3rd ed. p219: Elsevier. Scott, D. W. (1990) An unusual ulcerative dermatitis associated with linear subepidermal fibrosis in eight cats. Feline Practice 18 (3): 8-11.