Non-regenerative Anemia in Dogs

A decrease in red blood cells is called anemia. Typically, bone marrow will respond to this decrease by increasing red blood cell production. However, in non-regenerative anemia, the bone marrow response is inadequate when compared to the increased need. For this reason, dogs who suffer from anemia caused by lead poisoning are put in a very dangerous situation. Dogs that become anemic over a period of time will fare better than those who have a sudden onset of anemia. When the anemia progresses slowly, the body has time to adjust to the decreased red blood cell count. Dogs that become anemic quickly may die because of the sudden loss in red blood cells and oxygen.

There are three kinds of anemia: blood loss anemia caused by blood leaking out of the vascular system, as in the case of a wound; hemolytic anemia results from the destruction of red blood cells circulating within the blood stream; and non-regenerative anemia, which is caused by a decrease in red cell production.

The condition or disease described in this medical article can affect both dogs and cats. If you would like to learn more about how this disease affects cats, please visit this page in the PetMD health library.

Symptoms and Types

Pale gums or mucous membrane
Eyes and ears may be pale
Weakness
Depression
Sleeping more than normal
Stop grooming themselves
Decreased appetite
Increased breathing and heart rate

Causes

Bone marrow disease
Infections (tick disease).
Abscesses.
Cancer.
Kidney failure.
Drugs.
Toxic chemicals.
Radiation.
Lead poisoning.
Inherited disorders (giant Schnauzers, Border collies, and Beagles are most at risk).

Anemia is generally a symptom of another disease. Diagnosis is based on your dog’s history and clinical symptoms, physical examination, complete blood counts, urinalysis, iron testing, and bone marrow testing.

Regenerative Anemia in Dogs.

Blood is made up a cellular portion, and a liquid portion called plasma. This cellular makeup of blood includes the red blood cells, platelets, and white blood cells. When there are not enough red blood cells, the body is said to be anemic. One type of anemia, regenerative anemia, occurs when the body loses blood faster than it can be regenerated, despite the fact that new red blood cells are being produced in the bone marrow.

This condition can affect both dogs and cats. If you would like to learn more about how regenerateive anemia affects cats, please visit this page in the PetMD health library.

Symptoms and Types.

Pale gums.
Pale eyes and ears.
Weakness.
Rapid heart beat.
Depression.
Sleeping more than normal.
Failure to groom.
Weak appetite.
Excessive panting.
Heart murmur.
Hemolytic anemia:.
Yellow gums.
Yellowing of whites of eyes.

Causes.

Parasites (worms).
Fleas.
Wound.
Cancer.
Non-steroid anti-inflammatory drugs (NSAIDS), such as aspirin and ibuprofen.
Hemolytic anemia, which can be due to:.
Ingestion of toxic materials.
Ingestion of pennies.
Ingestion of onions and/or acetaminophen.
Bacterial and viral infections.
Defective red blood cells.
Autoimmune disease.
Parasites of the blood.

Diagnosis.

Complete blood test (CBC).
Packed cell volume test (PCV).
Urinalysis.
Bone marrow aspirate.

Overview of Anemia.

By Steven L. Marks, BVSc, MS, MRCVS, DACVIM, North Carolina State College of Veterinary Medicine.

Anemia.
Overview of Anemia.
Regenerative Anemias.
Blood Loss Anemia.
Hemolytic Anemia.
Nonregenerative Anemias.
Nutritional Deficiencies.
Anemia of Chronic Disease.
Renal Disease.
Primary Bone Marrow Diseases.

Anemia is defined as an absolute decrease in the red cell mass as measured by RBC count, hemoglobin concentration, and/or PCV. It can develop from loss, destruction, or lack of production of RBCs. Anemia is classified as regenerative or nonregenerative. With regenerative anemia, the bone marrow responds appropriately to the decreased red cell mass by increasing RBC production and releasing reticulocytes. With nonregenerative anemia, the bone marrow responds inadequately to the increased need for RBCs. Anemia caused by hemorrhage or hemolysis is typically regenerative. Anemia caused by decreased erythropoietin or an abnormality in the bone marrow is nonregenerative.
Clinical Findings:.

Clinical signs in anemic animals depend on the degree of anemia, the duration (acute or chronic), and the underlying cause. Acute anemia can result in shock and even death if more than a third of the blood volume is lost rapidly and not replaced. In acute blood loss, the animal usually presents with tachycardia, pale mucous membranes, bounding or weak peripheral pulses, and hypotension. The cause of the blood loss may be overt, eg, trauma. If no evidence of external bleeding is found, a source of internal or occult blood loss must be sought, eg, a ruptured splenic tumor, other neoplasia, coagulopathy, GI ulceration, or parasites. If hemolysis is present, the animal may be icteric. Animals with chronic anemia have had time to accommodate, and their clinical presentation is usually more indolent with vague signs of lethargy, weakness, and anorexia. These animals may have similar physical examination findings such as pale mucous membranes and weak peripheral pulses. The lack of expected clinical signs may alert the clinician to the time frame involved. Splenomegaly, abdominal distention, and/or heart murmur may be present, depending on the underlying cause of anemia.
Diagnosis:.

A complete history is an important part of the evaluation of an anemic animal. Questions might include duration of clinical signs, history of exposure to toxins (eg, rodenticides, heavy metals, toxic plants), drug treatments, vaccinations, travel history, and any prior illnesses.
Feline blood smear, Heinz bodies, new methylene blue.
Feline blood smear, Heinz bodies, new methylene blue.

Courtesy of Dr. John W. Harvey.
Feline blood smear, Heinz bodies, Wright-Giemsa.
Feline blood smear, Heinz bodies, Wright-Giemsa.

Courtesy of Dr. John W. Harvey.
Feline blood smear, Heinz bodies, Wright-Giemsa.
Feline blood smear, Heinz bodies, Wright-Giemsa.

Courtesy of Dr. John W. Harvey.

A CBC, including a platelet and a reticulocyte count, will provide information on the severity of anemia and degree of bone marrow response, and also allow for evaluation of other cell lines. A blood smear should be evaluated for abnormalities in RBC morphology or size and for RBC parasites. The RBC indices (measures of size and hemoglobin concentration) are calculated by automated cell counters calibrated for the species in question. RBC size is expressed by the mean corpuscular volume (MCV) in femtoliters and can reflect the degree of regeneration. Macrocytosis (an increase in the MCV) usually correlates with a regenerative anemia. Macrocytosis can be a heritable condition in Poodles without anemia and may be seen in anemic cats infected with feline leukemia virus. Microcytosis (a decrease in the MCV) is the hallmark of iron-deficiency anemia. The hemoglobin concentration of each RBC, measured in g/dL, is defined as the mean corpuscular hemoglobin concentration (MCHC). Terms used for description of abnormalities with MCHC include normochromia and hypochromia. Abnormalities in RBC morphology, such as basophilic stippling, can indicate lead intoxication. Heinz body formation indicates oxidative injury to the RBCs, secondary to toxin exposure (see Table: Toxic Causes of Anemia). Cats are more susceptible to Heinz body formation than other species, and cats without anemia can have a small number of Heinz bodies. The presence of schistocytes or spherocytes may also help identify the pathophysiology associated with the cause of anemia.
What does it mean to be \” anemic \”?

dog-752937_1920Anemia is a medical term referring to a reduced number of circulating red blood cells (RBC’s), hemoglobin (Hb or Hgb), or both. It is not a specific disease, but rather the result of some other disease process or condition. Hemoglobin delivers oxygen to the cells and tissues of the body, and a patient that is anemic will suffer from symptoms related to a lack of oxygen.

Red blood cells are produced in the bone marrow and are released into the blood, where they circulate for approximately three months in dogs and two months in cats. As they age or become damaged, they are then removed from the bloodstream and their components are recycled to form new red blood cells. The number of red blood cells may become reduced because of decreased production or increased loss.
What are the symptoms of anemia?

The most easily observed and common clinical sign of anemia is a loss of the normal pink color of the gums; they may appear pale pink to white when examined.

Anemic dogs also have little stamina or energy, so they seem listless or tire more easily. Pale gums and lethargy indicate the need to perform blood tests.
How is anemia diagnosed?

anemia-1There are several tests that are performed on the blood sample to diagnose anemia. The most common test is the packed cell volume (PCV) or hematocrit (HCT). These tests are often performed as part of a complete blood cell count (CBC). A blood sample is processed in a centrifuge to separate the red blood cells from the plasma (the liquid part of the blood). Once separated, the sample is measured to determine what percentage of the sample is made up of red blood cells. 35% to 55% of the normal dog’s blood will be red blood cells. If the PCV is below 35%, the dog is generally considered anemic. Others tests to determine if a dog is anemic include the red blood cell count (RBC) and the hemoglobin count.
What other tests are important when a dog is anemic?

When there is evidence of a low red blood cell count, it is important to know if the bone marrow is producing an increased number of new red blood cells in response to the lost red blood cells. When the body senses anemia, it releases immature (young) red blood cells from the bone marrow prematurely, and these immature red blood cells, called reticulocytes, can be stained for easier identification on the blood smear. The presence of increased numbers of reticulocytes indicates that the anemia is “responsive.” This means the body has identified anemia (” responding”) and is attempting to correct the deficit by releasing immature red blood cells. Most automated blood analyzers will detect the presence of reticulocytes to help your veterinarian quickly determine the body’s response to anemia.

A careful study of the blood smear is also important to look for blood parasites that might be causing red blood cell destruction and abnormal cells that could indicate leukemia (high white blood cell count).

A bone marrow biopsy or aspirate is obtained if there is concern that the bone marrow is not responding appropriately to the anemic state (” unresponsive” or non-regenerative anemia). A sample of bone marrow is withdrawn and analyzed, providing valuable information about its condition, and occasionally revealing the cause of the anemia.

Biochemical profiles and urinalysis are other important tests for anemic dogs. These tests evaluate organ function and electrolyte levels, providing important information about the overall health of the dog.

A fecal parasite exam is important to identify the presence of parasites in the intestinal tract that might be causing blood loss.
What causes anemia?

There are many diseases that can cause anemia. These are grouped into 1) diseases that cause blood loss, 2) diseases that cause hemolysis (red blood cell breakdown or destruction), and 3) diseases that decrease the production of red blood cells through bone marrow suppression.
What diseases of dogs cause blood loss?

The main causes of blood loss in dogs include:.

Trauma or injury to blood vessels or damage to internal organs, causing persistent bleeding.
Heavy infestations of blood-sucking parasites, such as fleas, ticks, and hookworms.
Tumors of the intestinal tract, kidneys, urinary bladder, and spleen.
Diseases that prevent proper blood clotting.

What diseases of dogs cause hemolysis?

The main causes of hemolysis or the destruction of red blood cells within the body in dogs include:.

Autoimmune disease, especially immune-mediated hemolytic anemia (IMHA or AIHA).
Blood parasites.
Chemicals or toxins.
Neoplasia (cancer).

What diseases of dogs prevent red blood cell production through bone marrow suppression?

The main causes of bone marrow suppression that result in decreased red blood cell production include:.

Any severe, chronic (long-lasting) disease (such as chronic kidney or liver disease).
Very poor nutrition or nutritional imbalances.
Autoimmune disease.
Hypothyroidism.
Chemicals or toxins.
Neoplasia (cancer).

Do dogs get iron deficiency anemia?

Iron deficiency anemia is a somewhat common disease in people, especially women.

However, iron deficiency is uncommon in dogs and is usually secondary to some form of chronic blood loss. It is occasionally seen in puppies that are being fed very poor diets or who have severe hookworm infections.
How is anemia treated?

If your dog’s anemia is so severe that it is life-threatening, a blood transfusion will be needed. Before giving a transfusion, blood samples will be taken for diagnostic testing. The main purpose of a blood transfusion is to stabilize the dog while the underlying cause of the anemia is determined and other treatments can begin to take effect.

Further, more specific treatment can be determined once the underlying disease causing the anemia has been diagnosed. Treatments may include corticosteroids, anthelmintics (de-worming medications), other medications, or surgery. Your veterinarian will outline a treatment plan specific to your dog’s needs, based on diagnostic test results.
What is the prognosis for anemia?

The prognosis for dogs with anemia is based on the specific diagnosis, as well as the patient’s general condition at the time of diagnosis.

If the anemia is diagnosed early and the dog is in relatively good health, the prognosis is good. Dogs that have severe anemia, either caused by toxins, cancer, or autoimmune diseases, or as a result of severe trauma have a less favorable prognosis.
This client information sheet is based on material written by: Ernest Ward, DVM.
© Copyright 2015 Lifelearn Inc. Used and/or modified with permission under license.