Feline viral skin diseases (Proceedings)


Feline viral skin diseases (Proceedings)

Nov 01, 2010

Feline Herpesvirus Dermatitis

Feline herpesvirus1 infection is most noted for causing URI disease and oral ulceration. Latent, persistent infection will occur in about 30% of affected cats. Vaccines do not prevent feline herpesvirus infection nor carriage or intermittent shedding of the virus. Recrudescence of signs or new lesions may occur with stress or concurrent illness. Virus usually resides in the trigeminal ganglion and the distribution of lesions usually follows the distribution pattern of this nerve.

Lesions in cats without URI signs are often found on the haired skin of the nasal planum, head, face, or ears. The feet and ventrum may be less commonly affected.

Given the pattern of the lesions, the most common DDx for Herpesvirus dermatitis are: mosquito hypersensitivity, EGC, SCC, and allergic or parasitic dermatitis.

Microscopic examination of lesions reveals ulceration and nectosis with an inflammatory infiltrate that may contain many eosinophils hence the confusion with EGC and parasitic lesions. The intranuclear inclusion bodies characteristic of herpesvirus may be difficult to find. It may be necessary to send tissue for immunohistochemistry or PCR on tissue biopsy samples. Confirmation of the diagnosis is important because immunosuppressive drugs can worsen this condition.

Treatment of herpesvirus dermatitis:

L-lysine 250-500 mg PO q12h

     30-30K U PO q24h
     250-500K U SQ 3X/wk for 6 weeks

Lactoferrin? 350 mg PO q24h
Acyclovir: Not effective against FHV1
Famcyclovir: 32 mg (¼ of 125 mg tablet) PO q12h
Imiquimod (Aldara®) 5% cream
      Topical immunomodulator
     Apply to lesions q48-72h

The prognosis for herpesvirus dermatitis is guarded because the viral infection will persist, lesions are difficult to resolve, and recrudescence is comon.

FHV1 may be related Idiopathic Ulcerative dermatitis (see below) due to paraesthesia of the nerves in the head and neck that results in self-mutilation.