Written by Vet

Anemia In Dogs: What Causes It?

Margarita Boyd
Written by: Dr. Margarita Boyd, BVSc MRCVS
Learn everything that you should know about anemia in dogs. Find specific details and discover how you can help your dog be healthier.

Anemia is when there is a lower than a normal number of red blood cells or hemoglobin (Hb) in the blood.

In dogs, it can lead to signs such as tiredness, exercise intolerance, weakness, decreased appetite, and a faster heart rate. It also causes the dog’s gums to be pale pink or nearly white.

Do you think your dog has anemia? In this article, we will discuss everything you need to know, including the most common signs of anemia, what causes it, how it is diagnosed and what the treatment options are.

What Are Red Blood Cells?

Let’s find out a little more about red blood cells and why they are so important.

Red blood cells are small discs that deliver oxygen around the body and pick up the waste gas carbon dioxide.

They are produced in the bone marrow and circulate in the blood vessels. Red blood cells circulate in the blood for about 3 months, after this time they are broken down and replaced by new red blood cells.

They are full of the protein hemoglobin (Hb), which picks up and carries oxygen. Hemoglobin gives blood its distinctive red color.

Signs Of Anemia In Dogs

Some dogs may have mild anemia, and not show any obvious signs. Other dogs may develop severe anemia suddenly, and quickly become weak and collapsed.

Common signs of anemia in dogs include:

  • Dog is tired and dull
  • Exercise intolerance, reluctance to play or run
  • Pale pink or white colored gums
  • Decreased appetite
  • Labored breathing
  • Faster heart rate
  • Signs of blood loss (e.g. nose bleed, blood in the stools or urine)
  • Bruising on your dog’s skin

Checking The Color Of Your Dog’s Gums

Do you know what color your dog’s gums are normally?

It’s not something that many people check regularly. Usually, healthy dogs have pink-colored gums. It’s a good idea to get in the habit of regularly checking the color of your dog’s gums, to know what his normal color is.

Simply lift up one of his lips and look at the gums above his teeth. Dogs with anemia have very pale pink or white colored gums, its an obvious sign and means they need treatment as soon as possible!

What Causes Anemia In Dogs?

Anemia is when there is a decreased number of red blood cells or the level of Hb in the blood. The number of red blood cells may be lower than normal due to:

  • decreased production of red cells in the bone marrow
  • destruction of red cells (e.g. an infection)
  • loss of red cells (e.g. bleeding)

There are a wide range of different diseases and conditions which can cause anemia in dogs.

One study found the most frequent causes of anemia in dogs were flea infestation (10.4 percent), hookworm infection (3.7 percent), heart murmur (2.2 percent) and chronic renal failure (1.4 percent).

Some common causes include:

1. Trauma

For example, a car accident can cause trauma or injury to blood vessels or damage to internal organs, leading to internal or external blood loss/bleeding.

2. Heavy Parasite Infections

Bloodsucking parasites such as fleas, ticks or hookworms can all cause anemia.

3. Cancer

Lots of different cancers can cause anemia, through the destruction of red blood cells or by reducing red blood cell production by suppressing the bone marrow.

4. Blood Clotting diseases

If the blood can’t clot properly, the dog is at a higher risk of having uncontrolled bleeding leading to anemia.

5. Immune-Mediated disease

The dog’s immune system attacks and destroys its own red blood cells e.g. immune-mediated hemolytic anemia (IMHA).

6. Toxins/poisons

Common causes of anemia in dogs include the ingestion of rat poison, onions, garlic or the metal lead.

7. Hypothyroidism

Anemia is a sign of an underactive thyroid gland.

8. Bone Marrow Disease

Any disease which affects the bone marrow can reduce the production of red blood cells e.g. aplastic anemia, leukemia.

9. Chronic Kidney Disease

Anemia is a common sign of chronic kidney disease in dogs. The kidneys produce an important hormone called erythropoietin (EPO), which signals to the bone marrow to make more red blood cells.

In kidney disease the amount of EPO is decreased, so the bone marrow makes fewer red blood cells.

10. Poor Nutrition

If a dog has a very bad diet, nutritional imbalances or is starved, then this can quickly lead to anemia.

11. Tick Transmitted Diseases

Many diseases transmitted by ticks can cause anemia in dogs e.g. babesia, ehrlichiosis

12. Internal Gastrointestinal (GI) Bleeding

Bleeding in the GI tract can be a result of intestinal disease, inflammation, or medications such as nonsteroidal anti-inflammatory drugs (NSAIDs). The dog may pass fresh red blood in the stools, or vary dark, black tarry stools.

How Is Anemia Diagnosed?

The vet may suspect anemia after carrying out a clinical exam and noticing pale-colored gums. Medical history is an important part of diagnosing anemia too.

Sometimes the underlying cause may be obvious, such as bleeding from a wound, in other cases, it may be more difficult to figure out what caused the anemia.

The vet will ask questions such as how long the signs have been present; if there is any known exposure to toxins such as rat poison, heavy metals, or toxic plants or foods; what medications or vaccinations your pet has had; if your pet travels; and if your pet has any previous illnesses.

Anemia can be diagnosed with a simple blood sample.

The most common test to diagnose anemia is the packed cell volume (PCV). PCV measures the percentage of red blood cells in the bloodstream. The Merck Veterinary Manual states that the normal PCV in dogs is between 35 and 57%. If the level of red blood cells is below 35 percent, the dog is considered anemic.

The PCV is often done as part of the complete blood cell count (CBC), which measures other cells in the blood such as the red blood cell count, white blood cell count, platelets and the hemoglobin count.

What Other Tests Might Be Needed?

The PCV is a quick and easy way to find out if a dog has anemia. However, it doesn’t tell the veterinarian why the dog has anemia. Sometimes, the underlying cause is obvious such as a bleeding wound or the dog ate rat poison.

However, most of the time the vet needs to do further tests to confirm the anemia and find out what exactly is causing it.

Let’s look at some common tests that might be needed:

1. Blood smear examination

A sample if blood is carefully examined under a microscope to check the dog definitely has anemia, and for clues for what has caused it.

The number of red blood cells, white blood cells, platelets and reticulocytes (immature red blood cells) can be manually verified, and checked for abnormalities.

The slide can be checked for signs of blood cancer, infection and some blood parasites too e.g. babesia.

2. Blood biochemistry

This blood test provides information about the general health of the dog. It checks things like the health of the kidneys and liver, levels of electrolytes, glucose (sugar), proteins, and calcium in the body.

3. Bone marrow biopsy

A bone marrow biopsy allows the vet to check for a bone marrow disease. The sample is analyzed in the laboratory, often giving important information about the anemia.

4. Reticulocyte count

When a dog is anemic, the bone marrow tries to combat the problem by producing and releasing immature (young) red blood cells called reticulocytes.

High levels of reticulocytes in the blood, mean the anemia is regenerative, and the dog’s body is attempting to correct the anemia.

If the level of reticulocytes is low, then it is called non-regenerative anemia and means the bone marrow is not producing more red blood cells to combat the problem.

Most vet clinics will have automated blood testanalysersto to detect the presence of reticulocytes. It’s important that a vet knows if the anemia is regenerative or not!

5. Slide agglutination test

This is a specific test to quickly check for immune-mediated hemolytic anemia (IMHA) in dogs.

6. Urinalysis

A urine sample can provide a vet with a lot of information, such as how well the kidneys are functioning and if a dog is dehydrated. It can also be useful to check for blood or infection in the urine sample.

7. X-rays and ultrasound

X-rays and ultrasound are important ways to check inside the dog’s body, to check for evidence of trauma, cancer, abnormal fluid, or infection.

8. Blood clotting tests

Normally the body responds to a damaged blood vessel or tissue, by forming a clot to stop the bleeding.

Specialized blood cells called platelets, and substances called coagulation factors are necessary for the body to form clots.

If a dog has a suspected blood clotting problem, then clotting tests can be done and platelet numbers and coagulation factors can be checked too.

9. Fecal parasite exam

A fecal parasite exam can identify intestinal parasites that might be irritating the gastrointestinal tract and causing blood loss.

What Is The Treatment For Anemia In Dogs?

The treatment for anemia depends on the underlying cause. Your veterinarian will be able to prepare a treatment plan for your dog depending on your dog’s diagnostic results.

If a dog has severe anemia or life-threatening blood loss, then a blood transfusion will be required. Usually, before a dog has a transfusion, a blood sample will be taken to check which blood type the dog is.

Surgery will be needed in cases of an internal bleed due to a damaged blood vessel or a damaged organ (e.g. spleen or liver). Immune-mediated hemolytic anemia is treated with immunosuppressive drugs such as corticosteroids.

Anti-parasite medications are required to treat dogs with anemia due to intestinal parasites, fleas or ticks.

Vitamin K is the treatment if the dog has ingested certain types of rat poison. Other types of blood clotting problems will need whole blood or plasma transfusions until the bleeding stops.

Antibiotics are needed to treat bacterial infections which cause anemia. For example, a doxycycline is a treatment option for tick-borne diseases ehrlichiosis and anaplasmosis.


Anemia is not a diagnosis, but merely a symptom of many possible diseases and conditions. Common signs in dogs include pale-colored gums and decreased energy.

If a dog with a mild to moderate anemia is diagnosed early and receives the correct treatment then the prognosis is good and the dog can make a full recovery.

However, dogs that have severe anemia, caused by conditions such as cancer, immune-mediated diseases or ingesting poison, have a less favorable prognosis.

If you think your dog has anemia, then a vet can take a simple blood test to check his levels of red blood cells. That way you can know for sure if your dog is anemic and needs any treatment!