Urticaria pigmentosa (‘Devon bumps’) is a relatively common skin disorder of cats, thought to be a nutritional deficiency since it responds to essential fatty acid supplements (EFAs). It is commonly reported in Devon rex and in the Sphinx cats (where a familial gene appears to be responsible)^[1][2].

Pathogenesis in the cat is unknown, but may be an immune-mediated response to dietary allergens, since cats often when fed hypoallergenic diets. In humans, urticaria pigmentosa is associated with cutaneous mast cell tumours and could well be due to a cutaneous metabolic disorder of the mast cell differentiation and growth factor, stem cell factors (SCF), which causes mast cell proliferation^[3].

EFAs help control the exacerbation of maculopapular eruptions, which usually occur on the ventral trunk. Symptoms may appear as greasy seborrhea on the head and dorsum. Pruritus and pigmented macules may also be present if cats are affected by secondary bacterial infection^[4].

Histologically, urticaria pigmentosa appears as perivascular to diffuse mastocytic and eosinophilic infiltrates in the dermis (Noli et al, 2004). Mast cell neoplasia or metastasis has not be reported^[5].

The condition appears to wax and wane in cats, and exacerbations are usually controlled with prednisolone and/or essential fatty acid supplements. In cases of severe pruritus, treatment with cyclosporin has induced clinical remission when given at doses of 7.5 mg/kg orally once daily 2 h before meals for 4 weeks. A 75% reduction in the initial lesions and pruritus were reported^[6].

References

1. ↑ Vitale, CB., Ihrke, PJ., Olivry, T & Stannard, AA (2008) Feline urticaria pigmentosa in three related Sphinx cats. Veterinary Dermatology 7(4):227 – 233
2. ↑ Guaguere, E & Prelaud, P (2000) A practical guide to feline dermatology. Merial, France
3. ↑ Noli, C & Scarampella, F (1999) Proc AAVD-ACVD, Maui pp:65
4. ↑ Noli, C et al (2004) Papular eosinophilic/mastocytic dermatitis (feline urticaria pigmentosa) in Devon Rex cats: A distinct disease entity or a histopathological reaction pattern? Vet Dermatol 15:253-259
5. ↑ Malik R et al (2009) Treatment of feline herpesvirus-1 associated disease in cats with famciclovir and related drugs. JFMS 11:40-48
6. ↑ Guaguere, E & Fontaine, J (2004) 5th Congress of Veterinary Dermatology, Vienna