Skin Disease, Autoimmune (Pemphigus) in Cats
Pemphigus in Cats
Pemphigus is a general designation for a group of autoimmune skin diseases involving ulceration and crusting of the skin, as well as the formation of fluid-filled sacs and cysts (vesicles), and pus filled lesions (pustules). Some types of pemphigus can also affect the skin tissue of the gums. An autoimmune disease is characterized by the presence of autoantibodies: antibodies that are produced by the system, but which act against the body's healthy cells and tissues – just as white blood cells act against infection. In effect, the body is attacking itself. The severity of the disease depends on how deeply the autoantibody deposits into the skin layers.
The hallmark sign of pemphigus is a condition called acantholysis, where the skin cells separate and break down because of tissue-bound antibody deposits in the space between cells. There are three types of pemphigus that affect cats: pemphigus foliaceus, pemphigus erythematosus, and pemphigus vulgaris.
In the disease pemphigus foliaceus, the autoantibodies are deposited in the outermost layers of the epidermis, and blisters form on otherwise healthy skin. Pemphigus erythematosus is fairly common, and is a lot like pemphigus foliaceus, but less afflictive. Pemphigus vulgaris, on the other hand, has deeper, and more severe ulcers, because the autoantibody is deposited deep in the skin.
Symptoms and Types
Foliaceus
- Scales, crust, pustules, shallow ulcers, redness, and itching of the skin
- Footpad overgrowth and cracking
- Occasional vesicles: fluid-filled sacs/cysts in the skin
- The head, ears, and footpads are the most commonly affected; this often becomes generalized over the body
- Gums and lips may be affected
- It is common for the nipples and nail beds to be affected in cats
- Swollen lymph nodes, generalized swelling, depression, fever, and lameness (if footpads are involved); however, patients are often in otherwise good health
- Variable pain and itchy skin
- Secondary bacterial infection is possible because of cracked or ulcerated skin
Erythematosus
- Mainly the same as for pemphigus foliaceus
- Lesions are usually confined to the head, face, and footpads
- Loss of color in lips is more common than with other pemphigus forms
Vulgaris
- The most serious of the pemphigus types
- More severe than pemphigus foliaceus and erythematosus
- Ulcers, both shallow and deep, blisters, crusted skin
- Affects gums, lips, and skin; may become generalized over the body
- Mouth ulcers are frequent, may result in loss of appetite
- The underarm and groin areas are often involved
- Itchy skin and pain
- Anorexia, depression, fever
- Secondary bacterial infections are common
Causes
- Autoantibodies: the body creates antibodies that react to healthy tissue and cells as though they are pathogenic (diseased)
- Excessive sun exposure
- Certain breeds appear to have a hereditary predisposition
Diagnosis
Your veterinarian will perform a thorough physical exam on your cat, including a blood chemical profile, a complete blood count, a urinalysis and an electrolyte panel. Patients with pemphigus will often have normal bloodwork results. You will need to give a thorough history of your cat's health, onset of symptoms, and possible incidents that might have precipitated this condition.
A skin exam is crucial. A skin tissue sample will be taken for examination (biopsy); and pustule and crust aspirates (fluid) will be wiped onto a slide to diagnose pemphigus. A positive diagnosis is achieved when acantholytic cells (i.e., separated cells) and neutrophils (white blood cells) are found. A bacterial culture of the skin may be used for identification and treatment of any secondary bacterial infections, and antibiotics will be prescribed in the event that there is a secondary infection present.
Treatment
Only severely affected patients need to be hospitalized for supportive care. Steroid therapy may be prescribed briefly to bring the condition under control. If corticosteroid and azathioprine therapy is prescribed, your cat will be switched to a low-fat diet, since these medications can dispose animals to pancreatitis. Your veterinarian will treat your cat with the drugs that are specifically suited to the form of pemphigus it has.
Living and Management
Your veterinarian will schedule follow-up appointments to see your cat every one to three weeks. Standard blood-work will be performed at each visit to check for progress. Once your cat's condition has gone into remission, it may be seen once every one to three months. The sun can worsen this condition, so it is important to protect your cat from excessive exposure to the sun.
