What is Canine Autoimmune Haemolytic Anaemia?

AIHA in dogs is an autoimmune condition which results in the destruction of the red blood cells and a corresponding decrease in the capacity of the blood to carry oxygen.

In AIHA, specific antibodies attached to the red blood cells cause the body's immune system to attack the cells. This mechanism, which is part of the body's defence system normally works to rid the body of old, diseased or damaged red blood cells, but in AIHA it attacks healthy cells which are killed faster than the body can replace them. The cellular debris, particularly in the form of spherocyte, found in a diagnostic blood smear will be indicative of haemolytic anaemia.

AIHA is sometimes confused with Resistant Idiopathic Thrombocytopenia. Whilst both diseases are treated in a similar manner, AIHA (sometimes referred to as IMHA) is a disease of the red-blood cells and thrombocytopenia is a disease of the platelets.

What are the symptoms?

The symptoms of AIHA can appear suddenly or they may be gradual and progressive. They usually relate to a decreasing red blood cell count and manifest themselves in the form of weakness, lethargy, and an increase in the heart and respiration rate. Another factor may be the build up of bilirubin, one of the breakdown products of haemoglobin, in the bloodstream causing a jaundice or pale appearance of the gums, ears and eyelids.

Owners may also observe an increase in temperature; vomiting or abdominal pain; and signs of blood in the urine or stool. A diagnosis of AIHA is made on the basis of these clinical signs as well as a CBC. A Coomb’s test should be performed to confirm the diagnosis. A small percentage of dogs that have AIHA will test negative on the Coomb’s test.

What is the causes of AIHA?

Many theories exist, but there are few clear answers. Factors include genetic predisposition; hormonal influences; viral infections; and possibly even temperament and stress.

Acknowledgement to Joanne Dickson and to her dog Meisha.

Canine Autoimmune Haemolytic Anaemia help and support

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