Feline facial skin diseases (Proceedings)

The goal of this seminar is to highlight common and uncommon causes of feline facial disorders via clinical presentation or “client complaint”. Two diseases, idiopathic facial dermatitis of Persians and pemphigus, will be discussed in more detail.

Damaged Whiskers

Bilaterally symmetrical broken whiskers are common cats with facial pruritus (atopy, food allergy, parasites). Often these cats will have concurrent chin acne. The ends of the hairs usually have split ends. If the whiskers are sheared a bit too cleanly, consider the possibility of mischief (child shearing the cat's whiskers with scissors!).  If the whiskers are curled, the cat may have brushed against a stove or other heat source.  Whiskers damaged as a result of play behaviour are usually confirmed by the owner reporting excessive roughness at home.

Nasal Depigmentation

Nasal tissue readily depigments due to inflammation (e.g. post upper respiratory infection). Cutaneous lupus is rare in cats but can present with nasal depigmentation.

Melting Lips

One of the most common lip lesions of cats is an indolent ulcer. If these lesions are symmetrical, consider systemic allergic disease (flea, atopy, food). If unilateral consider possible trauma at the site: cactus thorn, dermatophyte infection, flea bite. The “melting” of the lip margin is a common reaction to trauma.

Black Spots on the Lips

There are two common lip lesions of cats.  Comedones can be idiopathic or associated with facial pruritus. Lentigo is a hereditary pigmentary disease of orange cats that presents as pigmented macules on the lips, oral cavity, nose and ears.

Chin Swellings

The most common chin lesion of cats is acne. This can vary from mild to severe and present. Follicular plugging (acne) can be caused by disorders of keratinisation but also by dermatophytosis, Malassezia, and bacterial infections.  Contagious chin acne has been reported in cats. In older cats, chin swelling and/or alopecia may be sign of cutaneous lymphoma.

Hard Skin

True eosinophilic granulomas can develop on the face, lip or chin. The cat may look like it is “pouting”. Diagnosis is via skin biopsy; treatment is not necessary.  Exudative lesions may dry causing matting of the hair and “hard skin”. Radiant burns occur as a result of exposure to fire places, wood stoves, etc. An eschar develops at the site and it feels “hard”.

Nodules, Lumps and Swellings

“A lump is a lump is a lump until it is biopsied”-Unknown.  The differential diagnoses of lumps/nodules/swellings on the face of cat are legion. Plasma cell infiltrates on the nose of cats unassociated with concurrent plasma cell pododermatitis has been reported. Cryptococcus can cause swellings of the nose or  “Roman nose”.  Cuterebra migration can cause a lump anywhere on a cat's body but often these parasites are found in the skin of the face.  Other skin tumors include basal cell carcinoma, mast cell tumour, Bowen's disease (multifocal squamous cell carcinoma) and cutaneous lymphoma. 

Ulcerative Nasal Lesions

Viral infections are the primary differential diagnosis for ulcerative lesions on nose and mucocutaneous skin. Squamous cell carcinoma is a common neoplastic cause of ulcerative nasal lesions. Insect bite hypersensitivity can is a common skin disease of cats that generally affects the face and ears. The nose can be severely affected.

Ulcerative Facial Lesions

Eosinophilic plaque (pyotraumatic dermatitis) is the most common cause of ulcerative exudative facial lesions.  Insect bite hypersensitivity can appear as ulcerative areas on the face. Immune mediated diseases include erythema multiforme, drug reactions, and bullous pemphigoid. Any ulcerative lesion in a white cat should be suspect for squamous cell carcinoma. Lesions of epitheliotropic lymphoma can present with areas of hair loss, erythema and ulceration on the face and muzzle.

Facial Crusting

Diseases causing facial crusting include dermatophytosis, pemphigus, Notoedres. Idiopathic facial dermatitis of Persian cats is characterized by black exudate in the facial folds.

Facial Dermatitis of Persian Cats

This is an uncommon facial skin disease of long haired cats (Persian and Himalayan cats). It tends to start in young adult cats. Black waxy debris accumulates around the eyes, nasal folds, mouth and/or chin. Initially lesions are non-pruritic but as lesions become colonized by bacteria and yeast and inflamed, pruritus develops. Regional lymphadenopathy may be seen. This is a reaction pattern and although the presentation is “classic” other causes should be eliminated. Other common causes include, but are not limited to: dermatophytosis, combined bacterial and yeast infection due to allergies, food allergy, and demodicosis.

Treatment is consists of symptomatic therapy. The client  needs to understand that there is no specific therapy and life-long symptomatic treatment is required. In idiopathic cases, cyclosporine may benefit some cats. If so, improvement is usually seen within 4-6 weeks. Some cats will also respond to tacrolimus topical ointment. Response to prednisolone therapy has been inconsistent. In addition, in cats that do respond the benefit may be complicated by secondary effects associated with long term use. Although the disease is not life threatening, the prognosis is not good because cats require life-long topical and symptomatic therapy and constant monitoring lesions for microbial over growth. Affected cats should not be bred.

Pemphigus

Pemphigus foliaceus (PF/PE) is an immune mediated skin disease characterized by the loss of intercellular adhesion of cells in the epidermis. The disease can occur spontaneously or it can be the result of drug reactions. Clinically the disease is characterized by waves of intact pustules that rupture and crust resulting in crusting and scaling of affected areas.  In cats, lesions are most common on the face, nose, and inner pinnae. (Lesions can also involve the paws resulting in exudative paronychia and foot pad crusting. Lesions can become widespread and are more easily palpated than seen; small crusts covering areas of exudation are felt throughout the hair coat.) Intact pustules are difficult to find and are most common on the inner pinnae and around the mammae.  As mentioned before, lesions tend to develop in waves and cats may become depressed and febrile just prior to the start of a wave of lesion development. 

Definitive diagnosis is made via histological examination of skin biopsy specimens. A careful search for intact pustules must be made. In the absence of finding these lesions, numerous skin biopsies of crusted areas of the skin should be sampled. Often micropustules are found within characteristic lesions. Cytological examination of exudates from an intact pustule often can provide a working diagnosis if large rafts of acanthocytes are seen. This is a disease which can be managed but not cured. Most cats do very well with therapy.

Treatment options include glucocorticoid therapy, chlorambucil, adjunct topical steroids, and most recently cyclosporine.  Corticosteroids are usually the first drug of choice as remission can be rapidly induced. Oral prednisolone is administered until the lesions are in remission. The dose is then administered every other day and gradually reduced until the lowest possible dose is seen that will maintain the cat in remission. It is important to note that rarely, even short courses of prednisolone can cause diabetes mellitus in cats. Also, although rare, corticosteroid use has been associated with congestive heart failure in cats.   Some cases of feline PF do not respond to prednisolone and dexamethasone may be very effective in these cases.  In cases where corticosteroids cannot be used long term or do not provide adequate control, chlorambucil can be given concurrently with a glucocorticoid. There is a lag time of two to four weeks before maximum benefit may be seen. Complete blood counts should be monitored every weekly for the first month and then every two to four weeks as this drug can cause bone marrow suppression. Azathioprine is contraindicated in cats because of serious bone marrow toxicity.   Another option is the use of daily cyclosporine.  Given that this drug has a lag period of 30 days before maximum benefit is seen concurrent prednisolone therapy is needed.