Note for Pet Owners:

This information is provided by Provet for educational purposes only.

You should seek the advice of your veterinarian if your pet is ill as only he or she can correctly advise on the diagnosis and recommend the treatment that is most appropriate for your pet.

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In nature animals have evolved a sophisticated defence system that produces glycoproteins called immunoglobulins or antibodies in response to chemicals (antigens) on the surface of organisms (eg  bacteria, viruses) or other substances (eg toxins) that gain access to the body. The antibodies chemically bind with the antigens - an initial step in the process to remove them from the body. 

Under normal circumstances the body's immune system recognises tissues and cells that are part of itself, and the immune system will only produce antibodies against foreign cells. However, sometimes the controlling mechanisms fail and the immune system does produce antibodies which attack the animals own body tissues. These are called autoantibodies and the disease that results is called an autoimmune disease.

Autoantibodies may be formed against specific organs or specific types of cell (eg blood cells), or they may be non-organ specific. In the last category antibodies are often produced which act against nuclear material within the nucleus of cells and these are called antinuclear antibodies (ANAs). ANAs are commonly found  in some forms of autoimmune disease eg systemic lupus erythematosus (SLE)

e cause of autoimmune diseases is the production of autoantibodies against the animals own tissues. The underlying reasons for these disorders occurring are complex and not fully understood.

Infectious agents are thought to be the initiating factor in some of these disorders eg Systemic Lupus Erythematosus (SLE)

Breed Occurrence
There are several reports of possible increased incidence of autoimmune diseases in some breeds and sexes :

  • Cocker Spaniels,Old English Sheepdogs and Poodles may be predisposed to develop autoimmune haemolytic anaemia
  • Poodles are over-represented in reports of autoimmune thrombocytopenia
  • Female dogs more often develop autoimmune haemolytic anaemia, and autoimmune thrombocytopenia than males
  • Poodles and German Shepherds may be predisposed to develop Systemic Lupus Erythematosus
  • Toy breeds of dog may be predisposed to develop rheumatoid arthritis


The common signs of autoimmune disease in animals depend upon the target organ(s) for the autoantibodies :

Adrenal gland

  • Some cases of canine hypoadrenocorticism (Addisons disease) are due to autoantibody production against the adrenal glands.
  • Signs include :
    • Muscle weakness - the dog collapses during exercise
    • Depression
    • Sudden collapse and shock
    • Kidney failure
    • Inappetance
    • Diarrhoea - sometimes contains blood
    • Abdominal pain
    • Increased thirst (polydipsia)
    • Increased urine production (polyuria)
    • Weight loss


  • Autoimmune haemolytic anaemia (dogs, cats (rare - often secondary to leukaemia), cattle (very rare), horses (rare - usually secondary eg abscesses). It can occur with autoimmune thrombocytopenia.
  • Due to autoantibodies against the animals own red blood cells causing them to disrupt (called haemolysis)
  • Coombs test is positive in these patients
  • Anaemia may be present on routine haematological examination
  • Free haemoglobin is present in blood and urine
  • The animal may develop jaundice (accumulation of yellow pigment in tissues)
  • Affected animals are lethargic
  • Extremities (ears, feet, nose and tail) may become blue (cyanosed) or reddened, swollen, ulcerated and crusts may form.
  • Enlargement of the spleen may occur
  • Enlargement of lymph nodes may occur
  • Sometimes autoimmune haemolytic anaemia has a primary cause eg it can be induced by drugs
  • Autoimmune thrombocytopenia  (dogs, cats (rare), horses. It can be secondary to systemic lupus erythematosus - see below). It can occur with autoimmune haemolytic anaemia
    • Due to autoantibodies against platelets which are important in blood clotting.
    • Haemorrhages into the skin (small petechial haemorrhages, larger ecchymotic haemorrhages (patches) or sometimes massive haemorrhages - nose bleeds or internal bleeding into the abdomen or chest )
  • Systemic lupus erythematosus (SLE) - see below

Musculoskeletal System

  • Myasthenia gravis (dogs and cats)
    • The acquired form of this disease is associated with the production of autoantibodies against acetylcholine receptors on muscle. Signs include :
    • Poor exercise tolerance
    • Muscle weakness
    • Difficulty eating and swallowing
    • Regurgitation of food
    • Dilation of the oesophagus (megaoesophagus)
  • Rheumatoid arthritis - Autoantibodies against IgG are associated with rheumatoid arthritis the signs of which are :
    • Lameness
    • Swollen joints - often affects the same joints in the left and right limbs.
    • Restricted range of movement in joints, and in advanced cases there may be no movement in the joint
    • In some cases the joint dislocates because local ligaments rupture, and so there is an excessive range of movement
    • Crepitus (a grating sensation and clicking or cracking sound) is present when the joints are manipulated
    • High body temperature
    • Inappetance
  • Systemic lupus erythematosus (SLE) - see Multiple organ autoimmune diseases below.


  • Bullous Autoimmune Skin Disease
    • Pemphigus vulgaris (dogs and cats)
      • Erosions or ulcers around the mucocutaneous junctions (mouth, nails)
      • The lesions discharge serum and crusts form over the ulcers
      • Depression
      • Inappetance
      • Death
    • Pemphigus foliaceus (most common canine and equine autoimmune skin disease, also reported in cats and goats)
      • Small swellings under the surface of the skin (bullae or pustules)
      • Crusting
      • Scale (scurf or dandruff) formation
      • Loss of hair (alopecia)
      • Black pigmentation of the skin (hyperpigmentation)
      • Sloughing of the foot pads
      • Itchiness (pruritus)
      • Usually affects the head and nose, but can be generalised
    • Pemphigus vegetans (rare- dog))
      • Pustules
      • Crusting
      • Papilloma formation
      • Can be generalised or in the groin area
    • Pemphigus erythematosus (dog and cat)
      • Discharging sores
      • Crusting
      • Itchiness (pruritus)
      • Affects mainly the skin around the eyes, the ears and on the bridge of the nose.
      • The disease gets worse if the skin is exposed to sunlight
    • Bullous pemphigoid (dog and horse)
      • Erosions or ulcers around the mucocutaneous junctions (eg lips and mouth), the ears or the groin
      • The lesions discharge serum and crusts form over the ulcers
      • Depression
      • Inappetance
      • High body temperature - due to secondary infection


  • Autoantibodies against thyroglobulin (and occasionally against thyroid hormone T3)  are associated with lymphocytic thyroiditis  - the main cause of hypothyroidism in dogs. Signs of hypothyroidism include :
    • Bilateral hair loss (alopecia)
    • Thinning of the skin
    • Lethargy
    • Black pigmentation of the skin
    • Scurf (dandruff)
    • Lethargy
    • Obesity
    • Cold intolerance - seeks warm places to lie down
    • Reproductive problems.
    • Fat deposits in the cornea of the eye (lipidosis)
    • Dry eye (keratitis sicca)
    • Diarrheoa
    • Vomiting
    • Constipation
    • Slow heart rate (bradycardia)
    • Muscle weakness

Multiple Organ Autoimmune Diseases

  • Systemic lupus erythematosus (SLE) - (dogs and cats)
    • Arthritis (rheumatoid) in several joints - see above - most common presenting sign
    • Skin disease - second most common presenting sign
      • Bilaterally symmetrical loss of hair and production of scurf (scale or dandruff) 
      • Ulcerations and crusting form in severe cases - often affecting the ears, feet and head
    • High body temperature - does not respond to antibiotics, does respond to corticosteroids (present in over 50% of cases)
    • Inappetance
    • Anaemia - causes lethargy. Positive Coombs test.
    • Thrombocytopenia (low platelet count - less than 50,000 per cubic mm - present in about 30% of cases) - may lead to haemorrhages
    • Neutropenia - low white cell count (neutrophils) (present in up to 50% of cases)
    • Kidney disease - glomerulonephritis (in about 25% of cases) - protein leaks into urine.
    • Weight loss 
    • High total serum protein

Multiple organ system involvement is common and this can make diagnosis difficult.

Diagnosis depends upon tests to identify the circulating antibodies, or antibody-antigen complexes that form and other tests specific to the organ involved ;

Adrenal gland


Musculoskeletal system Multiple organ systems


  • Lymphocytic thyroiditis
    • Clinical signs
    • Low thyroid hormone (thyroxine - T4) concentrations in the blood
    • Histopathological examination of thyroid biopsy
    • Detection of antithyroglobulin antibodies in plasma

Treatment depends upon the organs involved . The aim is usually to reduce the immune response, however it should be remembered that this will also reduce the animals resistance to infection, so secondary complications may occur.

Adrenal gland

  • Addisons disease
    • Emergency treatment to replace fluids and electrolytes
    • Long term treat with mineralocorticoids eg fludrocortisone acetate at 0.1mg/kg body weight per day AND glucocorticoids eg prednisolone at 0.1-0.3mg/kg body weight per day


  • Autoimmune haemolytic anaemia
    • Immunosuppressive drugs  eg 
      • High dose corticosteroids - prednisone or prednisolone at 2mg/kg body weight twice daily by mouth
      • Cyclophosphamide - in acute, severe cases - 1.5-2.5mg/kg body weight daily by mouth
    • Blood transfusion - may be beneficial but controversial as haemolysis (disruption of the red cells) may occur
    • Removal of the spleen (splenectomy)
    • Treat any primary cause eg remove drug therapy if it is a drug-induced problem
  • Autoimmune thrombocytopenia
    • Immunosuppressive drugs :
      • High dose corticosteroids (see above)
      • Vincristine - 0.01-0.025mg/kg body weight intravenously every 7 days until platelet counts are normal
      • Cyclophosphamide - in severe cases - see above
    • Blood transfusion - severe cases
    • Splenectomy - if recurrent or non-responsive
    • Treat any primary cause eg drug-induced problem

Musculoskeletal system 

  • Myasthenia gravis 
    • Cholinesterase inhibitors eg pyridostigmine bromide at 10-60mg three times daily
    • Corticosteroids eg prednisone at 2-3mg/kg body weight per day
  • Rheumatoid arthritis
    • Aspirin - for its anti-inflammatory/analgesic effects - but not if SLE or thrombocytopenia are present
    • High dose corticosteroids (with/without aspirin) - see above
    • Cytotoxic drugs :
      • Azathioprine - 2mg/kg body weight daily or on alternate days or in combination with cyclophosphamide
      • Cyclophosphamide - 2 mg/kg body weight daily for 4 days per week
    • Gold salt therapy - body weight of sodium aurothiomalate every week
  • Systemic lupus erythematosus - see below
  • Enteropathic arthritis
    • Polyarthritis associated with inflammatory bowel disease has been reported to occur in dogs

Multiple organ autoimmune disease

  • Systemic lupus erythematosus (SLE)
    • High dose corticosteroids - see above
    • Azathioprine - for long term treatment
    • Cyclophosphamide - see above
    • Vincristine - if thrombocytopenia is present - see above



  • Lymphocytic thyroiditis
    • Synthetic thyroid hormone (T4) replacement therapy

In autoimmune diseases the prognosis is always guarded with only fair to poor chances of long term survival without treatment. However some respond well to therapy. Some examples are:

  • Autoimmune thrombocytopenia - prognosis is good if treated aggressively
  • Bullous autoimmune skin diseases - can often go into remission and be controlled with drugs.
  • Canine hypothyroidism due to lymphocytic thyroiditis can often be controlled well with thyroid hormone replacement therapy
  • Myasthenia gravis - prognosis is guarded. Some can undergo remission and be controlled, others progress and die
  • Systemic lupus erythematosis - prognosis is fair

Last Updated : March 2008