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Anemia Due to Bone Marrow Failure (or Toxicity) in Dogs

Aplastic Anemia in Dogs

The bone marrow plays a crucial role in producing and renewing vital cells such as red blood cells (RBCs), white blood cells (WBCs), and platelets. Every second, an estimated three million red blood cells are released into the bloodstream in some mammals, highlighting the significant workload of the bone marrow in maintaining normal cell levels in the body.

Aplastic anemia in dogs occurs when the bone marrow fails to replenish blood cells, leading to a life-threatening condition characterized by a deficiency of red blood cells. “Aplastic” signifies the malfunction of an organ, while “anemia” indicates a shortage of red blood cells. This condition arises when the normal bone marrow is replaced by adipose (fat) tissue, hindering the release of the necessary number of WBCs, RBCs, and platelets and resulting in an overall decrease in the blood cell count.

Red blood cells play crucial roles in oxygen transport and carbon dioxide removal, white blood cells are vital for fighting infections and foreign particles, and platelets are essential for blood clotting and preventing hemorrhage. Symptoms of aplastic anemia directly correlate with the functions of these cells, with all three types of cells typically affected. Without treatment, severe cases of aplastic anemia can lead to death in affected dogs.

Symptoms and Types

The symptoms of aplastic anemia can vary depending on which of the three types of cells are primarily affected and the severity of the condition. Each type of cell has its own function in normal bodily processes. Here are some of the symptoms associated with aplastic anemia:

  • Recurrent infections
  • Fever
  • Petechial hemorrhage (red or purple spots on the skin caused by tiny hemorrhages)
  • Blood in the urine (hematuria)
  • Nosebleeds (epistaxis)
  • Black-colored feces (melena)
  • Pale mucous membranes
  • Weakness
  • Lethargy


Aplastic anemia in dogs can stem from various factors, including infections, toxins, drugs, and chemicals. Here are some of the primary causes:


  • Canine parvovirus infection
  • Infections from rickettsial organisms (e.g., ehrlichia)

Drugs and chemicals:

  • Administration of estrogen
  • Chemotherapeutic drugs
  • Albendazole (used for parasitic treatment)
  • Certain types of antibiotics
  • Non-steroidal anti-inflammatory drugs (NSAIDs) prescribed for pain and inflammation relief
  • Radiation therapy in cancer patients


To diagnose aplastic anemia in your dog, it’s essential to provide a detailed history of your dog’s health and the onset of symptoms. Your veterinarian will conduct a comprehensive physical examination and order a series of laboratory tests, including complete blood counts, biochemical profiles, and urinalysis. These tests will yield crucial information for an initial diagnosis. If cell counts fall significantly below normal ranges, it suggests a positive result.

Your veterinarian will also screen your dog for any infectious diseases. However, the most pivotal diagnostic test for aplastic anemia involves bone marrow sampling. During this procedure, a small sample of bone marrow is collected either through aspiration or biopsy. Microscopic examination of the bone marrow sample provides critical insights into the bone marrow’s structure and any developmental abnormalities affecting various cell types.


Upon confirming the diagnosis, your veterinarian will commence immediate treatment for your dog. Depending on the severity of the condition, your dog may require hospitalization for monitoring and treatment. Aplastic anemia presents various challenges, and supportive therapy will be initiated to address your dog’s nutritional and energy needs. In severe cases, whole blood transfusions may be necessary to address significant anemia.

Given that aplastic anemia largely involves immune system dysregulation, the primary treatment involves immune system suppression using medications such as cyclosporine A. Cyclosporine and similar agents help dampen the bone marrow’s excessive response. Additionally, drugs supporting bone marrow function are typically prescribed for these patients. Antibiotics are administered to treat existing infections and prevent further ones from occurring.

Living and Management

Throughout your dog’s hospitalization, your veterinarian will conduct daily monitoring to assess your dog’s condition. Blood tests will be repeated periodically to evaluate the progress of treatment. In certain cases, additional bone marrow sampling may be necessary to assess the bone marrow’s response.

Regrettably, survival rates for dogs with aplastic anemia are low despite comprehensive care and treatment. Younger dogs generally have a better prognosis, but even if initial recovery is achieved, complete recovery may take several weeks to months to occur.

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