Autoimmune diseases cover a varied group of disorders that arise from a dysfunctional immune system. Normally the dog’s immune system fights against foreign bacteria and viruses that invade the body. Autoimmune diseases occur when the immune system attacks the body`s own cells instead.
There are many different types of autoimmune disease depending on the body system that is under attack. Some have a gradual onset, but others can be immediately life threatening.
Systemic Lupus Erythematosus (SLE) typically occurs in middle age dogs, German Shepherds, Setters and sheep dogs are breeds that are predisposed. Multiple organs can be targeted including the skin, joints, kidneys, nervous and cardiovascular systems. Clinical signs are variable depending on the cells targeted but include lameness, ulceration of face or feet, hair loss, increased thirst and loss of skin pigment. Most cases respond to steroid treatment which works by suppressing the faulty immune system.
Autoimmune Haemolytic Anaemia (AIHA) occurs when the immune system attacks the red blood cells and they are destroyed more rapidly than the spleen and bone marrow can replace them. The red blood cells transport oxygen around the body so when their numbers are depleted the most common symptoms are weakness and lethargy. Gums can be visibly pale and in severe cases the dog can collapse. Any dog can be affected but Cocker Spaniels are predisposed and is more common in middle aged female dogs. Usually the condition can be controlled with immunosuppressive doses of steroids but in extreme cases a blood transfusion may be required.
Immune Mediated Thrombocytopaenia (AIT) occurs when the immune system attacks the dog’s platelets which form blood clots. You may notice bruising on the gums or hairless skin, blood in the urine or faeces or nose bleeds. Rarely dogs present in crisis and require a blood transfusion. Most respond very well to steroid immunosuppressive treatment. Both AIHA and AIT are diagnosed with blood tests. These are also used to monitor response to treatment so make sure the red blood cell or platelet numbers are returning to normal. Most dogs can be gradually weaned off treatment to a low maintenance dose.
Autoimmune skin diseases vary in severity. Pemphigus causes scabby blisters and sores around the head and feet which can spread around the body. Discoid Lupus Erythematosus is related to SLE but only affects the face leading to depigmentation and sores. It is advised to use sunscreen and avoid excessive sunlight. Many autoimmune skin diseases can be treated with topical steroids to reduce drug side effects but in more severe cases oral treatment is required. These are usually diagnosed with a skin biopsy.
Immune Mediated Polyarthritis can be seen with SLE or on its own. Most dogs present with a fever, shifting lameness, painful joints and enlarged lymph nodes. Dogs respond to treatment with steroids and usually remain in remission.
In all these diseases, steroids are the first line of treatment but not all cases respond, and other more aggressive immunosuppressant drugs need to be added. These dogs will need to be monitored closely to make sure the drugs are not having unwanted side effects. Most immune diseases can be well controlled, some will go into complete remission, but some will require lifelong treatment.