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.
Systemic lupus erythematosus has a guarded prognosis. Discoid lupus erythematosus has a better prognosis.
Two forms of lupus occur in companion animals: systemic lupus erythematosus (SLE) and discoid lupus erythematosus (DLE). If your cat is diagnosed with lupus, the treatment plan will depend upon which of these forms of the disease your animal has. The effects of and treatment protocols for each type of lupus are very different. However, they both are caused by an autoimmune disorder which essentially causes the cat's body to attack itself.
Treating Systemic Lupus Erythematosus
SLE is rare but probably underdiagnosed in cats. It cannot be cured. Persians, Siamese and Himalayans are predisposed. The goals of treating SLE are to resolve the clinical signs of the disease and prevent progressive renal or other organ failure. Because effects of the disease naturally wax and wane, not all cases need to be treated aggressively at all times.
Cats suffering from severe, acute effects of SLE may need to be hospitalized for initial management until the condition can be stabilized. Enforced rest and a protein-restricted diet are hallmarks of initial treatment. A number of drugs are available for use in acute cases, including corticosteroids to reduce inflammation and suppress the abnormal immune reaction, and non-steroidal anti-inflammatory medications, commonly called "NSAIDs." NSAIDs and steroids normally are not given in combination because of the increased risk of gastrointestinal ulceration. Cats should not be given azathioprine, because cats tend to have adverse reactions to this drug. Your veterinarian will decide upon the appropriate medical protocol for your cat. In order to alleviate the dramatic, progressive, unpredictable and often painful effects of SLE, chronic treatment is designed to suppress the cat's immune system (which is essentially attacking itself). Often a combination of steroids and other immunosuppressant drugs is used to combat the effects of lupus. Supportive care, enforced rest and dietary restrictions are important components of treatment. In most cases, treatment (or more accurately, management) of SLE must be continued for life, although doses of medication can be tapered if remission occurs.
Long-term immunosuppressive therapy has adverse side effects that must be taken into account when designing a treatment protocol for cats with SLE. These include bone marrow suppression and increased risk of localized or systemic infection, such as bronchopneumonia or urinary tract infections, among other things. Weight gain is also common with steroid use. Unfortunately, use of immunosuppressive drugs is the only viable method for managing SLE. There is no surgical option. Regular physical examinations, urinalyses and blood tests should be conducted on an outpatient basis to monitor the side effects of immunosuppressive medication. Affected animals should not be bred. Given its unpredictable and progressive course, the prognosis for cats with SLE is guarded to poor.
Treating Discoid Lupus Erythematosus
Like SLE, discoid lupus erythematosus cannot be cured. However, it is more manageable than the systemic form of the disease. It is one of the most common immune-mediated skin diseases of companion animals – common in dogs and rare in cats. The goal of treatment is to control and resolve the skin lesions that accompany this disease. DLE is a variant of lupus that primarily affects the face - particularly the hairless areas of the nose. Treatment protocols can include oral antibiotics, topical ointments, oral vitamin E, oral essential fatty acid supplements and oral or topical steroids.
Clinical signs of SLE and DLE usually worsen with exposure to ultraviolet light. Accordingly, affected animals should be kept out of the sun as much as possible. Owners can apply waterproof, high SPF sunscreen to affected areas as well.
As with SLE, cats with DLE should be checked by a veterinarian regularly to assess progression of the disease and to monitor the success of treatment. Affected cats should not be used for breeding. Unlike SLE, the prognosis for cats with DLE is fairly good, since this disease is progressive but not life-threatening and is not common in cats. Those cats that do develop DLE often go into remission, making chronic immunosuppressive therapy less commonly necessary. Moreover, cats with DLE usually feel fine, even though the condition can be disfiguring.