AIHA in dogs

Introduction

Autoimmune hemolytic anemia (AIHA), also known as immune-mediated hemolytic anemia (IMHA), in dogs is a 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 / IMHA antibodies attached to the red blood cells cause the body's immune system to attack the cells. This mechanism, which is normally works to rid the body of old, damaged or diseased red blood cells is part of the body's natural defence system. Unfortunately in AIHA it attacks healthy cells which are killed faster than they can be replaced. Cellular debris, often in the form of spherocyte, found in a blood smear can be indicative of haemolytic anaemia.

AIHA is not the same as Resistant Idiopathic Thrombocytopenia. Both diseases are treated in a similar manner, but thrombocytopenia is a disease of the platelets rather than the red blood cells.

Symptoms of AIHA

AIHA symptoms, appearing gradually but sometimes suddenly usually relate to a decreasing red blood cell count and show themselves in weakness, lethargy, and increased heart and respiration rates. Bilirubin may also build up. This is one of the breakdown products of haemoglobin causing a pale appearance of the gums, ears and eyelids.

You may also observe increased temperature; vomiting or abdominal pain; and signs of blood in the urine or fecal matter. AIHA diagnosis is a combination of these clinical signs and a CBC. A Coomb's test will confirm the diagnosis, but a small percentage of dogs with AIHA will test negative on the Coomb's test.

How could my dog get AIHA?

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

Further information

The VetNet^® forum has been providing an information, support and help portal for owners with pets suffering with AIHA since 1997. VetNet^® is a DMR^® initiative.