How Autoimmune Hemolytic Anemia Affects Dogs
Autoimmune hemolytic anemia (AIHA), also called immune-mediated hemolytic anemia (IMHA), is a common, often manageable but potentially fatal condition in domestic dogs. Basically, the dog’s immune system begins attacking and destroying its own red blood cells. This significantly reduces the blood’s capacity to carry oxygen to body tissues, which in turn causes the observable signs of the disease.
Symptoms of Canine Autoimmune Hemolytic Anemia
Dogs suffering from autoimmune hemolytic anemia typically show the same signs as dogs suffering from other forms of anemia. These can include one or more of the following:
- Pale mucous membranes (pallor of the gums and nasal tissues)
- Disinterest in normal activities
- Lack of appetite
- Bloody stool (hematochezia; melena)
- Discolored urine (dark brownish or orange-ish urine due to abnormal presence of blood, hemoglobin and/or bilirubin)
- Excessive thirst (polydypsia)
- Excessive urination (polyuria)
- Difficulty breathing (rapid, shallow breathing; respiratory distress; dyspnea; shortness of breath)
- Exercise intolerance
- Elevated heart rate (tachycardia)
- Bounding pulses
Jaundice (above) refers to the yellow color that is seen in tissues when the liver is overwhelmed with bilirubin, which is a yellow byproduct of the breakdown of red blood cells. In a healthy dog, the liver will absorb, metabolize and excrete bilirubin as red blood cells reach the end of their normal life span. In a dog with autoimmune hemolytic anemia, the liver simply cannot keep up with processing the amount of bilirubin caused by destruction of RBCs. This causes the dog’s mucous membranes – especially in the gums, skin, ears and eyes - to take on an unusual yellowish discoloration.
Further examination by a veterinarian may reveal an enlarged spleen (splenomegaly), an enlarged liver (hepatomegaly), a heart murmur and/or enlarged lymph nodes.
Dogs at Increased Risk
Autoimmune hemolytic anemia can develop in dogs of either sex, any age and any breed. However, many studies suggest that middle-aged spayed female dogs are overrepresented in the affected population. Breeds that seem predisposed to IMHA include the Cocker Spaniel, English Springer Spaniel, Miniature Poodle, Irish Setter, Collie, Miniature Schnauzer, Doberman Pinscher, Miniature Pinscher, Lhasa Apso, Shih Tzu, Bichon Frise, Old English Sheepdog, Vizlsa, Scottish Terrier and Finnish Spitz. Some authorities suggest that dogs are at an increased risk in the months of May and June, although the reason for this spring seasonality is unclear.
Survival rates for dogs with autoimmune hemolytic anemia are fairly low. However, if it is caught early in its course, treatment and management can be effective. If your dog exhibits any of the symptoms described above, please see your veterinarian as soon as you can.