If your dog has anemia, there’s been a drop in the number of his red blood cells. Red blood cells carry oxygen to the cells in the body and pick up carbon dioxide. A low red blood cell count can be the result of blood loss, the destruction of the red blood cells, or an inadequate production of new red blood cells.
There are many causes of anemia, including excessive blood loss due to trauma, immune-mediated diseases (when the body attacks its own cells or organs), cancer, genetic defects, kidney disease (or diseases in the other major organs), infectious diseases and bone marrow disease. Human and pet medications, as well as certain foods, can also bring about this condition. Onions, for instance, don’t only cause bad breath; they can also cause anemia!
All dogs can get anemia in one form or another, because there are so many different conditions and diseases that result in an anemic state. For example, if your dog has a parasitic infestation, such as worms or fleas, she could experience blood loss and anemia—another reason why flea and tick prevention is so important!
Certain medications, like cancer-therapy drugs and anti-inflammatory drugs, can also increase the risk of anemia.
Warning signs that your dog is anemic or becoming anemic include:
These signs can vary from pet to pet and really depend on the underlying cause of the anemia. In some situations, your dog may present no signs at all!
When a dog is anemic, it is crucial to identify the underlying cause. Your veterinarian may recommend various tests, depending on your dog’s symptoms and history.
These tests may include:
Treatment of anemia depends on the underlying condition. It includes stopping blood loss as well as treatment of bacterial, viral, toxic, and autoimmune conditions. If the anemia is severe, a blood transfusion may be necessary.
Since anemia is caused by other conditions, it is best to focus on prevention of those conditions. Protecting your dog from common parasites by using preventives is important, as well as contacting your veterinarian immediately if you see any signs of anemia.
If you have any questions or concerns, you should always visit or call your veterinarian – they are your best resource to ensure the health and well-being of your pets.
Peter Kintzer DVM, DACVIM
Anemia Overview: Anemia is a condition where the body has a lack of red blood cells (RBCs). In most anemia cases, the RBCs are either not produced in the bone marrow, lost from the circulatory system, or are destroyed. While anemia is one of the more common blood problems seen in dogs, it usually is more of a symptom of an underlying disease rather than a disease of its own. Some of the more common problems that cause anemia are discussed below.
Introduction/Causative Agent: Immune-mediated hemolytic anemia (also called auto-immune hemolytic anemia) occurs when an animal’s immune system malfunctions and begins to think that the red blood cells of the body are "foreign." The animal’s body then creates antibodies against its own red blood cells. The red blood cells are destroyed and anemia (a lack of red blood cells) results. This can be caused by a number of underlying problems, including heartworm disease, exposure to certain household drugs or toxins, certain tumors, or exposure to infectious diseases like Ehrlichia, Leptospira, and Babesia.
Clinical Signs: Animals with IMHA often become lethargic and weak. The mucous membranes (gums and vulva) are pale, and the heart rate and breathing are faster than normal. Blood work can reveal a low packed cell volume (PCV) and icteric (yellow tinged) serum. A urinalysis might show hemoglobin or bilirubin in the urine. These animals will often not feel well and will stop eating.
Diagnosis: In most cases, a primary disease is diagnosed first and then IMHA being diagnosed secondarily as a resulting disease. Blood work and clinical signs will help in the diagnosis.
Treatment/Prognosis: Supportive care, restful environment, nutritional supplements (including iron), and systemic (whole body) steroids are the best treatment options. Cautious fluid therapy can also help. In extreme cases, a blood transfusion may be necessary. After the initial crisis, patients may live a relatively normal life, returning weekly or monthly for PVC tests to make sure the anemia is controlled.
Introduction: Heinz-body anemia occurs when an animal is exposed to certain oxidants, plants, or chemicals. These substances cause the red blood cells to develop Heinz-bodies. Once Heinz-bodies form in the red blood cells, the cells are destroyed and anemia results. Heinz-Body anemia is considered a regenerative anemia, meaning that it triggers the body to produce more red blood cells from the bone marrow to compensate for the ones that are lost.
Causative Agents: Acetaminophen (more a problem in cats), zinc, vitamin K3, benzocaine, mothballs, methylene blue, onions, and even garlic are among the more common causes of Heinz-body anemia in dogs.
Clinical Signs: The animal will usually be lethargic, weak, and may have a fever. Gums might appear pale. In severe cases, the urine can look brownish red because of the hemoglobin in it.
Diagnosis: Animals that have anemia caused by Heinz-bodies can be identified by examining a sample of the animal’s blood stained with methylene blue using a microscope. The Heinz-bodies will appear as small, dark blue spots on the red blood cells. Knowing if there is any chance the animal may have been exposed to one of the previously mentioned chemicals also aids in diagnosing.
Treatment: Animals with Heinz-body anemia should be kept quiet and rested. Removing the plant, oxidants, or chemical cause is necessary to prevent further occurrences. Oxygen therapy might also help. Severe cases may require a blood transfusion.
Introduction: Nonregenerative anemia happens when an animal is anemic and its body does not create more red blood cells to compensate.
Causative Agents: Nonregenerative anemia is usually a symptom of an underlying problem. Infections, inflammation, and tissue injury can be a cause of the initial problem. Kidney disease, liver disease, endocrine disease, chronic lead poisoning, or chronic vitamin or mineral deficiency (iron deficiency) also can result in nonregenerative anemia.
Clinical Signs: The animal will usually appear weak and lethargic. Their gums can be pale, and they will not want to eat much. They might drink and urinate more often than normal. Their heart rate might be faster than normal. Signs may also include symptoms of the primary cause, such as mouth sores for renal failure or central nervous system signs for lead poisoning.
Diagnosis: Blood work may reveal a low packed cell volume, and depending on the primary disease, certain forms of blood cells that are not normally seen may show up on blood slides. Examples would include schictocytes for iron deficiency and acanthocytes for liver disease.
Treatment: Nonregenerative anemia usually is resolved when the primary disease is addressed and treated. Fluid therapy with Lactated Ringers may help if the animal has suffered severe blood loss or is in shock.
Introduction: Von Willebrand disease is a bleeding disorder that changes the way the platelets act in an animal’s body. While the animals have enough platelets in their bloodstream, the platelets are not able to cling to any holes in the blood vessels to stop bleeding. Animals with Von Willebrand disease can suffer severe blood loss from very minor injuries. At least 60 dog breeds have been diagnosed with Von Willebrand disease, with some of the more commonly affected breeds being standard poodles, Shetland sheepdogs, Scottish terriers, schnauzers, rottweilers, golden retrievers, German shepherds, German shorthairs, dachshunds, corgis, basset hounds, and Airedales. Of all the breeds, this problem is most often associated with Doberman pinschers.
Causative Agent: The Von Willebrand Factor (vWF), named for the scientist who discovered it, is usually present on platelets and is responsible for allowing the platelets to cling to holes in the blood vessels. This causes the blood to clot and stop bleeding. In patients with Von Willebrand disease, the vWF is missing from some or all of the platelets, so they do not adhere to the vessel walls and the bleeding does not stop. Von Willebrand disease is usually separated into three types. In Type I, the vWF is missing from most of the animal’s platelets. Type II is a rare form, which usually affects German pointers. In Type III, there is virtually no vWF found at all in the animal’s bloodstream.
Clinical Signs: The animal will often take a long time to stop bleeding, even from minor injuries. In severe cases, they may spontaneously bleed from the mucous membranes (including the gums, genitals, inside the eyelid) and could even have blood in their urine. Some pets might show signs of gastrointestinal bleeding, such as blood in their stool.
Diagnosis: After observing the clinical symptoms, some additional testing can help to confirm a diagnosis. Blood work may reveal anemia due to the loss of blood. The platelet count will usually be normal, but a vWF assay might show lower levels of the Von Willebrand Factor. Another common test is to prick the animal’s gums or the inside of the lip and time it to see how long the blood takes to clot.
Treatment/Prognosis: Some animals may require blood transfusions to replace lost blood or to help control bleeding. Dogs recovering from injury or surgery should be monitored carefully to ensure the bleeding has stopped and is under control. Some concentrated forms of the vWF, such as Cryoprecipitate, are available if needed. If veterinarians and owners will take precautions during surgical procedures and attempt to prevent injuries that may cause bleeding, animals with Von Willebrand Disease usually can lead a normal life.
When a dog becomes anemic, the loss of blood and red blood cells can induce a very fatigued state. It is likely that your dog will no longer have any desire for his normal activities, and he will probably sleep more often than usual.
In addition to that, you will also notice a lack of appetite in your dog. With the loss of red blood cells, your dog will find it very hard to partake in any activity that requires his energy. Eating is no exception.
One of the most noticeable signs of anemia is the whitened color of your dog's gums and ears. Extremities of the body are always the first portion to lose blood flow when there is not a sufficient amount. The body does not consider extremities a necessity, and it will redirect the flow of the blood to vital organs, such as the heart and lungs.
, BVSc, MS, MRCVS, DACVIM (SAIM), North Carolina State College of Veterinary Medicine
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.
, DVM, DACVIM (Small Animal Internal Medicine and Oncology), Tufts University
The main function of red blood cells (also called erythrocytes) is to carry oxygen to the tissues, where it is required for cellular metabolism. Oxygen molecules attach themselves to carrier molecules, called hemoglobin, which are the iron-containing proteins in red blood cells that give the cells their red color. Oxygen is carried from the lungs and delivered to all body tissues by the hemoglobin within red blood cells. Oxygen is used by cells to produce energy that the body needs. Carbon dioxide is left behind as a waste product during this process. The red blood cells then carry that carbon dioxide away from the tissues and back to the lungs, where it is exhaled. When the number of red blood cells is too low, this is called anemia. Having too few red blood cells means the blood carries less oxygen, resulting in fatigue and weakness. When the number of red blood cells is too high, which is called polycythemia, blood can become too thick, impairing the ability of the heart to deliver oxygen throughout the body. An animal’s metabolism is geared to protect both the red blood cells and the hemoglobin from damage. Interference with the formation or release of hemoglobin, the production or survival of red blood cells, or their metabolism causes disease.
The total number of red cells, and thus the oxygen-carrying capacity, remains constant over time in healthy animals. Mature red blood cells have a limited life span their production and destruction must be carefully balanced, or disease develops.
Production of red blood cells begins with stem cells in the bone marrow and ends with the release of mature red blood cells into the body’s circulation. Within the bone marrow, all blood cells begin from a single cell type called a stem cell. The stem cell divides to form immature forms of red blood cells, white blood cells, or a platelet-producing cell. Those immature cells then divide again, mature even more, and ultimately become red blood cells, white blood cells, or platelets.
The rate of blood cell production is determined by the body’s needs. Erythropoietin, a hormone produced by the kidneys, stimulates development of red blood cells in the bone marrow. Erythropoietin increases if the body lacks oxygen (a condition called hypoxia). In most species, the kidney is both the sensor organ that determines how much oxygen the body’s tissues are receiving and the major site of erythropoietin production so chronic kidney failure leads to anemia. Erythropoietin plays a major role in determining whether to increase the number of stem cells entering red blood cell production, to shorten maturation time of the red blood cells, or to cause early release of red blood cells. Other factors that affect red blood cell production are the supply of nutrients (such as iron and vitamins) and cell-cell interactions between compounds that aid in their production. Some disorders are the direct result of abnormal red blood cell metabolism. For example, an inherited enzyme deficiency reduces the life span of red blood cells and a condition known as hemolytic anemia.
It is important to remember that a decrease in the total number of red blood cells in the body (anemia) is a sign of disease, not a specific diagnosis. Anemia may be caused by blood loss, destruction of red blood cells (hemolysis), or decreased production. In severe blood loss anemia, red blood cells are lost, but death usually results from the loss of total blood volume, rather than from the lack of oxygen caused by loss of red blood cells. Hemolysis may be caused by toxins, infections, abnormalities present at birth, drugs, or antibodies that attack the red blood cells. In dogs the most common cause of serious hemolysis is an antibody directed against that dog’s own red blood cells (immune-mediated hemolytic anemia).
Factors that may prevent red blood cell production include bone marrow failure or malignancy, loss of erythropoietin secondary to kidney failure, certain drugs or toxins, longterm debilitating diseases, or antibodies targeted at developing red blood cells. The outlook and treatment depend on the underlying cause of the anemia.