Definition of Lupus
Lupus is a general term for a rare autoimmune disease in cats characterized by the formation of antibodies against the cat’s own tissues. There are two different types of lupus in cats, and they have very different symptoms and effects. While there is no exact known cause of lupus in cats, there does seem to be a genetic predisposition to the disease.
How Lupus Affects Cats
There are two types of lupus that affect cats: discoid lupus erythematosus (DLE) and systemic lupus erythematosus (SLE). Lupus cannot be cured, but sometimes the symptoms can be managed or controlled. Himalayans, Persians and Siamese cats seem to be the most affected breeds.
Systemic lupus erythematosus involves the cat’s own immune system attacking itself systemically and is the more serious form of lupus in companion cats. Unfortunately, the prognosis for this type of lupus is very poor. Shifting-leg lameness is the most common sign of SLE, followed by lethargy, anorexia and skin lesions (especially in areas exposed to sunlight). An owner may notice her cat limping on a front leg, then not limping at all. Weeks or months later, the same cat might start limping on a back leg, or on the other front leg. This sporadic lameness is attributable to swollen, painful joints. Other signs can include periodic fever, oral ulcers, arthritis, pale gums, hair loss, increased thirst, increased urination and a number of neurologic abnormalities. Oral corticosteroid therapy is often prescribed to try and suppress the cat’s immune system; however, long-term steroid use has many adverse side effects. Keeping the cat out of the sun can also help to reduce outbreaks of this form of lupus. Systemic lupus erythematosus may go into remission with steroid treatment, but for many cats a secondary recurrence of the disease is often fatal. Diagnosis of SLE cannot be made based on any single test. The veterinarian must consider a constellation of clinical signs and exclude other possible underlying causes of those signs (cancer, infection, etc).
Discoid lupus erythematosus (DLE) is considered to be a relatively benign variant of SLE that primarily affects the skin – especially on the face. The most commonly affected site is the hairless surface of the nose, called the “nasal planum.” DLE is an autoimmune disorder that causes depigmentation, redness, scaling, erosions, ulcerations and crusting on the nose, face and lips of cats and dogs. It is much more common in companion dogs than in cats. It is not a systemic disorder. A course of oral steroids is often prescribed to lessen the symptoms of DLE. In addition to oral steroids, antibiotics with anti-inflammatory properties are also commonly prescribed to calm inflammation of the affected tissues and address any secondary bacterial infections. Steroid creams can be applied to the face and ears too; however, most cats remove the creams as soon as they are applied. Keeping the cat out of the sun will also help to reduce future occurrences of the signs of this disorder.
Causes of Lupus in Cats
The causes of lupus are still unknown, although a genetic predisposition is suspected.
Preventing Lupus in Cats
There is no known way to prevent either SLE or DLE in cats, other than by not breeding affected animals.
Special Notes
Systemic lupus erythematosus has a guarded prognosis. Discoid lupus erythematosus has a better prognosis.