Guide to Dog Anemia

Overview

Dog anemia is a decreased number of red blood cells or iron in the blood (hemoglobin) or both. It's not a disease in itself but is a symptom of something else. While anemia in people is often caused by iron deficiency in the diet, this is rarely the case in dogs.

An anemic condition means that the red blood cells are decreasing and not being replaced as fast as they should. Since red blood cells come from the bone marrow, diagnosis starts with condition that affects this area of the body such as leukemia, bone marrow cancer and drugs that are having a toxic effect.

Anemia is also caused by the body using red blood cells faster than normal such as when their is a bleeding condition. Common areas for bleeding include the digestive tract and if your dog is suffering from hookworm or heartworm.

Anemia in dogs can be caused by a number of things, including:

• Blood loss: caused by trauma or injury, parasites like fleas, ticks and worms, and diseases that prevent the blood from clotting
• Breakdown of red blood cells: Disease with this as a byproduct such as autoimmune diseases, blood parasites, and cancer
• Disease that prevents the production of red blood cells: such as autoimmune diseases where your dogs body attacks its own red blood cells (called immune-mediated hemolytic anemia - INHA), an under active thyroid, and cancer.

There are two groupings used when characterizing anemia, regenerative and non-regenerative.

Regenerative Dog Anemia

This type of anemia is characterized by blood loss that can threaten the life of the dog while at the same time, the dog is capable of producing red blood cells, it means that the bone marrow is still functioning in a normal range. This type of anemia is primarily caused by either blood loss or a condition called hemolysis or immune-mediated hemolytic anemia (IMHA) which refers to cases where red blood cells are created, but destroyed prematurely by the immune system.  the cause of IMHA is not well understood.

• Breeds Predisposed to IMHA: Shih Tzu, Miniature Schnauzer, Labrador Retriever, American Cocker Spaniel
• Tick related diseases have been associated with immune-mediated disorders

Non-regenerative Anemia

If a dog is not able to product red book cells the disease is characterized as non-regenerative anemia. Often this form of anemia is mild and does not cause clinical signs. It can usually be cured by addressing the underlying condition. The prognosis is better in dogs with anemia that gradually worsens vs. those that have a sudden onset of  anemia. When the anemia progresses gradually a dog's body has more time to adjust to the condition.

There are multiple causes for this type of canine anemia including:

• Diseases: diseases such as infectious parvovirus, some cancers and Ehrlichia (bacterial problem) can suppress the bone marrow and red blood cell creation.
• Medications: if a medication affects the bone marrow it can affect blood cell production. Chemotherapy for example will result in low white blood counts. Estrogen creams may be associated with bone marrow suppression. Select pain medications (aspirin, acetaminophen) and antibiotics can also cause bone marrow suppression.
• Chronic Endocrine disorders: Hypothyroidism and Addison's disease can trigger anemia.
• Anemia of Inflammatory Disease: diseases such as chronic kidney disease, which affects older dogs can cause anemia. Kidney disease causes a depletion of erythropoietin, a hormone that signals that bone marrow to make new red blood cells.  In the case of anemia related kidney disease there is a treatment that uses darbepoetin, a synthetic form of erythropoietin that is tolerated well by dogs.

Symptoms

When reviewing symptoms a veterinarian will want to know the rapidity of onset and will use the clinical exam to help determine the severity of the disease.

Symptoms of canine anemia include:

• loss of appetite (anorexia)
• listlessness
• fatigue
• pale gums
• jaundice (yellow skin discoloration)
  
• dark urine
• vomiting
• increased breathing or respiratory rate (tachypnea)

You'll probably notice the listlessness, but your vet will notice the pale gums when he or she examines your dog.

Less common dog anemia symptoms include:

• dyspnea (difficulty breathing)
• sudden death
• seizures

Canine Anemia Diagnosis

There several tests that may be done to check for dog anemia. One is called the packed cell volume (PCV) or hematocrit. In this test, a blood sample is spun in a centrifuge to separate the red blood cells from the plasma (the liquid part of the blood). Between 35 - 55% of the dog's blood should be red blood cells. If the hematocrit is lower than 35, the dog is anemic.

Other tests may be done, including a red blood cell count and a hemoglobin count.

If your dog is anemic, tests will be done to find the cause of the anemia. Tests include checking the blood sample for increased numbers of immature red blood cells, which means that the bone marrow is responding to the need for more blood and making more red blood cells. Tests also include checking the blood for parasites that might be destroying red blood cells.

• Bone marrow biopsy: often identifies the cause of the anemia. It will check for things like leukemia.

Bone Marrow biopsy being performed at the Proximal Femur

• Urine sample:  to evaluate organ function.
• Fecal sample:  to check for intestinal parasites that may be causing blood loss.

There are two breakthrough tests now available to diagnose anemia in dogs:

Capsule Endoscopy

A new test, capsule endoscopy, detects gastrointestinal bleeding by having the dog patient swallow a pill that has an embedded camera. The camera records images and transmits them to the veterinarian wirelessly as it moves through the gastrointestinal tract. The camera can detect causes of anemia as well as tumors, ulcers and parasites. Another benefit is the ability of the technique to be used without anesthesia.  The capsule endoscopy also overcomes the limitation of traditional endoscopy which can only view the small intestine.

PCR (Polymerase Chain Reaction)

This test detects the enzyme polymerase in lab tests. The test identifies the DNA of infectious organisms that can cause anemia in dogs such as Babesia sp. and Mycoplasma sp.

Treatment

Blood Transfusion

While mild cases do not require a blood transfusion, more severe cases do to stabilize your dog while the cause of the dog anemia is diagnosed and the underlying cause is treated.

The donor red cells from a blood transfusion temporarily improve oxygen capacity and stabilize the dog until the underlying cause of the anemia can be found and treated. Dogs will be transfused with blood or the same type, or in an emergency and if it is the first transfusion, with blood of any type (they can tolerate different types of blood better than humans). For subsequent transfusions, dogs can only receive blood with the same type as their own.

General Treatment

Intravenous fluids can help to improve the circulation of the remaining red blood cells as long as there are a sufficient number of cells available in the body.

Dog Hemolytic Anemia (Regenerative Anemia)

In the case of dog hemolytic anemia or immune-Mediated Hemolytic Anemia (IMHA), there is no known cause (regenerative anemia). Treatment for this condition is prednisone which slows the bodies attack on the red blood cells. In severe cases the spleen may need to be removed. One third of dogs do not respond to treatment, but if your dog responds, then the prognosis is good.

The disease is known for causing secondary infections and problems with liver and kidney function. In severe cases there is a risk of kidney failure if not treated.

Non-regenerative Anemia

As indicated above, removal of the underlying condition can result  in a cure for anemia triggered by a medication, disease or endocrine problem.

Dog Anemia Diet

Dietary change for dog anemia depends on the underlying cause of the problem. For example, nutritional management of chronic renal failure (kidney disease) calls for reduced quantities of protein in order to reduce non essential amino-acids. This results in a reduction in nitrogenous wastes.

Ensure that foods have adequate levels of vitamin B6 (improves red blood cell function) and vitamin B12 (supports enzyme function, low levels can lead to lack of white blood cells and changes in the bone marrow).

Levels recommended for normal dogs:

• Vitamin B12: 9 μg (micrograms) per day for a dog weighing 33 pounds consuming 1,000 calories per day.
• Vitamin B 6: .4 mg per day for a day weighing 33 pounds consuming 1,000 calories per day.

Dog with kidney and endocrine system problems might also benefit from a herbal supplement such as Kidney Support. Check with your veterinarian if this is the issue. For dogs with AIHA (auto immune hemolytic anemia) ask your veterinarian about using an iron supplement.

Brochures

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References

Basic Approach to Anemia Diagnosis
Tvedten, Harold William

Hound Health Handbook: The Definitive Guide to Keeping Your Dog Happy, Healthy & Active

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