Congenital Hypoplastic Anemia

Hypoplastic anemia is a broad category of anemias characterized by decreased production of red blood cells. Other names used to describe this condition include aplastic anemia. This category of anemia includes individuals with congenital or genetically transmitted predisposition to aplastic anemia.

Aplastic Anemia

Aplastic anemia is a condition that results from injury to the blood stem cell, a cell that gives rise to other blood cell types after it divides: red blood cells, white blood cells, and platelets). As a result, there is a reduction in all blood cell types with this type of anemia. This reduction is called pancytopenia. The affected types of blood cells are red cells, white cells, and platelets. The cause of aplastic anemia is unknown, but is thought to be an autoimmune process (the body reacting against its own cells). Causes of other types of aplastic anemia may be chemotherapy, radiation therapy, toxins, drugs (antibiotics), pregnancy, inherited or congenital (present at birth) disorders, or systemic lupus erythematosus.¹

Drugs that have been associated with stem cell injury in dogs include estrogen, phenylbutazone, meclofenamic acid, phenobarbital, phenytoin, colchicine, chloramphenicol, thiacetarsamide, albendazole (a broad-spectrum anthelmintic).

Signs

Signs arise as the consequence of bone marrow failure and the loss of blood cell production. Low red cell count (anemia) leads to fatigue and weakness. Low white cell count (leukopenia) causes an increased risk of infection. Low platelet count (thrombocytopenia) results in bleeding, especially of mucus membranes and skin.¹

Aplastic anemia is treated with androgens, high-dose methylprednisolone, cyclosporin A (CyA), antithymocyte globulin (ATG), antilymphocyte globulin (ALG), hematopoietic growth factors such as G-CSF, and bone marrow transplantation.²

Other Inherited Types of Anemia

Cobalamin deficiency is very rare in dogs and cats and usually results from hereditary absence of intrinsic factor cobalamin receptos which as an autosomal recessive trait. This anemia has been reported in Border Collie, Giant Schnauzer, Beagle and cats.³

References

1. Idiopathic aplastic anemia. MedlinePlus
2. Masanao Teramura, M.D., Hideaki Mizoguchi, M.D. Special Education. The 'Oncologist, Vol. 1, No. 3, 187-189, June 1996
3. Mary Anna Thrall. Veterinary Hematology and Clinical Chemistry