The short version
Anemia occurs when there is a decrease in the number of red blood cells, which can be measured by red blood cell count or hemoglobin concentration. It can develop from loss, destruction, or lack of production of red blood cells. Anemia is classified as regenerative or nonregenerative. In a regenerative anemia, the bone marrow responds appropriately to the decreased number of red blood cells by increasing production of new blood cells. In a nonregenerative anemia, the bone marrow responds inadequately to the increased need for red blood cells. Anemias due to bleeding or the destruction of existing red blood cells are usually regenerative. Anemias that are caused by a decrease in the hormone that stimulates red blood cell production or by an abnormality in the bone marrow are nonregenerative.
Signs and Diagnosis
A complete medical history is an important part of diagnosing anemia. Questions a veterinarian may ask include how long signs have been present; if there is a history of exposure to toxins such as rodent poisons, heavy metals, or toxic plants; what drug treatments and vaccinations the pet has had; where the pet has traveled; and any prior illnesses.
A complete blood count is another diagnostic tool your veterinarian will use to provide information on the severity of the anemia, the degree of bone marrow response, and the condition of other types of blood cells. A test should be performed to evaluate red blood cell size and shape and to check for red blood cell parasites (some of which are discussed later in this chapter).
How Are Blood Cell Counts Done?
A blood sample is taken and placed in a test tube containing an anticoagulant to stop it from clotting. It is then transported to a laboratory.
The process is generally done using automated equipment. The blood is well mixed and placed on a special rack on the analyzer. This instrument has many different components to analyze different elements in the blood. The cell counting component counts the numbers of red and white blood cells and platelets. The results are printed out or sent to a computer for review by a technician.
Because an automated cell counter samples and counts so many cells, the results are very precise. However, certain abnormal cells in the blood may be identified incorrectly. To be sure the results are correct, a technician reviews the blood smear on a slide and identifies any abnormal cells or blood parasites present.
Hemolytic Anemia
Hemolytic anemias occur when red blood cells are destroyed. They are usually regenerative. Toxins, red blood cell trauma, infections, immune system defects, and red blood cell membrane defects can all cause hemolytic anemias.
Immune-mediated Hemolytic Anemia
In dogs, the most common cause of hemolytic anemia is immune mediated. This type of anemia can occur on its own or as a result of tumors, infection, drugs, or vaccinations. The body no longer recognizes red blood cells as self and develops antibodies to circulating red blood cells, leading to their destruction.
Dogs with immune-mediated hemolytic anemia are usually jaundiced, sometimes have a fever, and may have an enlarged spleen. They can show mild, slow-developing signs and not appear to be in any pain, or they can suddenly be in severe crisis. Your veterinarian will tailor treatment to the animal’s signs. Any underlying infections will be treated and unnecessary drug therapy discontinued. Intravenous fluid therapy may be started and supplemented with blood transfusions if necessary. Drugs are also given to suppress the immune system in order to stop the destruction of red blood cells.
Blocking of a blood vessel in the lungs by a piece that has broken away from a blood clot (known as pulmonary thromboembolism) is a risk for dogs with immune-mediated hemolytic anemia. The underlying cause is unknown, but the risk may be reduced by supportive care with fluids and blood transfusions. Fluids are important to keep kidneys functioning properly and to protect the kidneys from the high concentrations of circulating bilirubin (the reddish yellow pigments in blood that cause jaundice). If the risk for forming blood clots is high, anticoagulant medication may also be given.
Microangiopathic Hemolysis
Microangiopathic hemolysis occurs when red blood cells are damaged due to turbulent flow through abnormal blood vessels. It can be seen in dogs with severe heartworm infections, blood vessel tumors (for example, hemangiosarcoma), twisting of the spleen, and disseminated intravascular coagulation, a condition in which small blood clots develop throughout the bloodstream, blocking small blood vessels and depleting the platelets and clotting factors needed to control bleeding. Treatment requires correcting the underlying disease.
Frequently asked questions
Anemia dogs?
The Merck Veterinary Manual covers this in the article linked on this page. Anemia occurs when there is a decrease in the number of red blood cells, which can be measured by red blood cell count or hemoglobin concentration. I… If your dog is unwell, contact your veterinarian — this page is educational, not a diagnosis.
Anemia dog symptoms?
The Merck Veterinary Manual covers this in the article linked on this page. Anemia occurs when there is a decrease in the number of red blood cells, which can be measured by red blood cell count or hemoglobin concentration. I… If your dog is unwell, contact your veterinarian — this page is educational, not a diagnosis.
Anemia dog treatment?
The Merck Veterinary Manual covers this in the article linked on this page. Anemia occurs when there is a decrease in the number of red blood cells, which can be measured by red blood cell count or hemoglobin concentration. I… If your dog is unwell, contact your veterinarian — this page is educational, not a diagnosis.