Anaemia in dogs

What is anaemia?

Anaemia is a medical condition characterised by a decreased number of circulating red blood cells or a reduced concentration of hemoglobin in the blood. It is not a disease itself but rather a sign of an underlying health issue affecting the production, destruction, or loss of red blood cells.

What are the signs of anaemia?

If your dog is suffering from anemia, you may notice one or more symptoms that can vary depending on the underlying cause of the condition. Common signs include:

• Pale gums, eyes, or ears

• Weakness or lethargy

• Black or tarry stools

• Rapid pulse or breathing

• Swelling of the jaw or face

• Vomiting

• Loss of appetite

• Weight loss

How is anaemia diagnosed?

Diagnosis of anaemia in dogs begins with a thorough physical examination and a complete medical history to understand the duration and severity of symptoms, exposure to toxins, medications, and any prior illnesses. The primary diagnostic tool is a complete blood count (CBC), which measures the red blood cell count, hemoglobin concentration, hematocrit, and other blood components. A low red blood cell count or hemoglobin level confirms anaemia.

Additional blood tests may include a blood smear to examine the shape and size of red blood cells and to detect blood parasites that may cause destruction of red blood cells. Biochemical profiles and urinalysis help assess organ function, especially kidney and liver health, which can influence red blood cell production.

Imaging studies such as X-rays or ultrasounds may be recommended to identify internal bleeding sources, tumors, or other abnormalities. A fecal examination can detect intestinal parasites that cause blood loss.

In cases where the bone marrow's response to anaemia is unclear, a bone marrow biopsy or aspirate may be performed. This involves collecting a bone marrow sample to evaluate its ability to produce red blood cells and to identify any bone marrow diseases or cancers.

What other tests are important when a dog is anaemic?

When a dog is diagnosed with anaemia, further tests are crucial to determine the underlying cause and the body's response to the condition. One important test is the reticulocyte count, which measures the number of immature red blood cells in the bloodstream.

An increased reticulocyte count indicates a regenerative anaemia, meaning the bone marrow responds appropriately by producing new red blood cells to replace those lost or destroyed. Conversely, a low reticulocyte count suggests a nonregenerative anemia, where the bone marrow is not producing enough red blood cells.

A detailed examination of a blood smear is also important. This helps identify abnormal red blood cell shapes, sizes, or the presence of blood parasites that might be causing hemolysis. Additionally, a slide agglutination test may be performed to detect autoimmune hemolytic anemia, where the immune system attacks the body's own red blood cells.

If the bone marrow's condition is uncertain or if nonregenerative anaemia is suspected, a bone marrow biopsy or aspirate is often necessary. This procedure involves collecting a bone marrow sample to assess its ability to produce blood cells and to detect diseases such as bone marrow suppression, cancers, or pure red cell aplasia.

Other diagnostic tests include biochemical profiles and urinalysis to evaluate kidney and liver function, as these organs play a role in red blood cell production and overall health. A fecal parasite exam is important to identify blood-sucking parasites that may cause chronic blood loss. Imaging studies, such as X-rays or ultrasounds, may be recommended to locate internal bleeding, tumors, or organ abnormalities contributing to anaemia.

What are the different types of anaemia?

Blood loss anaemia

Blood loss anaemia occurs when there is a significant loss of blood from the dog's body, either externally due to trauma, surgery, or wounds, or internally from bleeding disorders, tumors, stomach ulcers, or heavy parasite infestations.

This type of anaemia is classified as regenerative because the bone marrow typically responds appropriately by increasing red blood cell production to replace those lost. However, if the blood loss is severe and prolonged, it can overwhelm the body's ability to compensate, leading to severe anemia and requiring immediate veterinary intervention.

Aplastic or non-regenerative anaemia

Aplastic or non-regenerative anaemia arises when the bone marrow fails to produce sufficient red blood cells. This condition can result from bone marrow diseases, kidney disease, exposure to toxins, chemotherapy drugs, certain medications, or infections such as parvovirus.

In these cases, the bone marrow response is inadequate, and the red blood cell count remains low despite the body's need. Diagnosis often involves bone marrow biopsy to assess marrow health, and treatment focuses on addressing the underlying cause and supportive care to stimulate red blood cell production.

Methemoglobinemia

Methemoglobinemia is a rare form of anaemia caused by an abnormal increase in methemoglobin, a form of hemoglobin that is unable to carry oxygen efficiently. This condition can be inherited due to certain genetic disorders or acquired through exposure to toxins, including some human medications like acetaminophen, ibuprofen, or benzocaine.

Dogs with methemoglobinemia may exhibit symptoms of oxygen deprivation such as weakness, rapid breathing, and cyanosis (a bluish tint to the gums and skin). Treatment involves removing the source of the toxin and supportive care to improve oxygen delivery.

Hemolytic anaemia

Hemolytic anaemia results from the premature destruction of red blood cells faster than the bone marrow can replace them. This can be immune-mediated, where the dog's body mistakenly attacks its own red blood cells (immune mediated hemolytic anaemia), or non-immune mediated, caused by toxins, parasites, hereditary diseases, or low phosphorus levels.

Dogs with hemolytic anaemia may show jaundice, pale gums, lethargy, and rapid heart rate. Treatment often requires immunosuppressive medications, blood transfusions, and addressing any underlying diseases or infections.

What diseases cause Hemolysis?

Hemolysis refers to the destruction of red blood cells, which can lead to hemolytic anemia if the rate of destruction exceeds the bone marrow's ability to produce new cells. Several diseases and conditions can cause hemolysis in dogs:

• Immune-mediated hemolytic anemia (IMHA): This is the most common cause of hemolysis in dogs. It occurs when the dog's immune system mistakenly targets and destroys its own red blood cells. IMHA can be primary (idiopathic) or secondary to infections, cancers, drugs, or vaccines.

• Infectious diseases: Certain infections caused by parasites (such as Babesia and Mycoplasma species), bacteria, or viruses can directly damage red blood cells, leading to hemolysis.

• Toxins and drugs: Exposure to certain toxins (like zinc, copper, or certain plants) and medications can cause oxidative damage to red blood cells, resulting in their destruction.

• Hereditary red blood cell defects: Some breeds have inherited conditions that make their red blood cells more fragile or prone to destruction.

• Microangiopathic hemolysis: This occurs when red blood cells are mechanically damaged as they pass through abnormal blood vessels or clots, seen in conditions such as disseminated intravascular coagulation (DIC), hemangiosarcoma, or heartworm disease.

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

Bone marrow suppression leads to non-regenerative anemia due to insufficient production of red blood cells. Diseases and conditions that can cause bone marrow suppression in dogs include:

• Bone marrow diseases: Such as aplastic anemia, myelodysplastic syndrome, leukemia, or bone marrow cancers.

• Chronic kidney disease: Reduced production of erythropoietin, a hormone produced by the kidneys that stimulates red blood cell production.

• Toxin exposure: Certain chemicals, drugs (including chemotherapy agents), and radiation can damage the bone marrow.

• Infections: Some viral infections like parvovirus can suppress bone marrow function.

• Nutritional deficiencies: Deficiencies in essential nutrients like iron, vitamin B12, folate, and copper can impair red blood cell production.

• Immune-mediated bone marrow suppression: The immune system may attack the bone marrow cells themselves, reducing their ability to produce blood cells.

Do dogs get iron deficiency anaemia?

Yes, dogs can develop iron deficiency anaemia, although it is less common than in humans. Iron deficiency in dogs typically results from chronic blood loss rather than inadequate dietary intake. Common causes include:

• Chronic gastrointestinal bleeding: Due to ulcers, tumors, or parasites such as hookworms.

• Severe infestations of blood-sucking parasites: Such as fleas or ticks, especially in puppies.

• Poor iron absorption: Rarely, certain diseases can affect iron absorption.

Iron deficiency anaemia results in smaller than normal red blood cells (microcytic anaemia) and reduced hemoglobin concentration, impairing oxygen delivery to tissues. Treatment involves addressing the underlying cause of blood loss and iron supplementation.

How is anaemia treated?

Treatment of anaemia in dogs depends on the underlying cause and severity of the condition. Key approaches include:

• Blood transfusions: For severe anaemia or when rapid stabilisation is needed, blood transfusions provide immediate red blood cells to improve oxygen delivery.

• Medications: Corticosteroids and other immunosuppressive drugs are commonly used to treat immune-mediated hemolytic anaemia. Antibiotics may be prescribed for infections, and deworming medications for parasitic causes.

• Addressing underlying diseases: Surgery may be necessary to remove bleeding tumors or damaged organs. Treatment of kidney disease, liver disease, or chronic conditions is essential.

• Supportive care: Intravenous fluids to maintain blood volume and kidney function, nutritional support including a healthy diet, and supplements such as iron or vitamins.

• Monitoring and follow-up: Regularly scheduled wellness exams and blood tests help detect early signs of anaemia and monitor response to treatment.

What is the prognosis for anaemia?

The prognosis for dogs with anaemia varies widely and depends on the underlying disease causing the anemia, the dog's overall condition, and how quickly treatment is initiated. Dogs with mild anaemia due to treatable causes often have a good prognosis. However, severe anaemia, especially from immune-mediated conditions, cancer, or chronic diseases, can carry a guarded to poor prognosis.

Early diagnosis and effective treatment improve outcomes. Dogs with regenerative anaemia generally have a better prognosis than those with non-regenerative anaemia. Close collaboration with a primary care veterinarian and possibly veterinary specialists is important to manage the disease and improve quality of life.

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Don’t wait any longer to give your playful pup or golden oldie the protection they deserve. For more information on topics similar to this, take a look at our blog where we cover a range of dog related health issues.

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