What is Heinz body anemia?
Heinz body anemia is a type of anemia (reduced number of oxygen-carrying red blood cells) characterised by the presence of Heinz bodies (HB) on the red blood cell which leads to its destruction (hemolysis).
Heinz bodies form when red blood cells are exposed to oxidative agents which cause changes (denaturation) to the hemoglobin chains within the red blood cells. Macrophages (a type of white blood cell) clear affected red blood cells in the spleen.
Methemoglobinemia is a second type of oxidative damage that can occur due to the presence of methemoglobin (an abnormal form of hemoglobin) in the blood. Methemoglobin can not bind to oxygen, leading to decreased availability of oxygen to the tissues.
Types of anemia:
- Blood loss
- Non-regenerative
- Regenerative
Anemia from blood loss can be external (from a wound for example) or internal bleeding.
Non-regenerative anemia is due to a decrease in the production of red blood cells in the bone marrow.
Regenerative occurs when red blood cell production is normal however they are destroyed faster than they can be made.
Heinz body anemia is a form of regenerative anemia, red blood cells are made however the immune system destroys them due to the formation of Heinz bodies.
Causes
Most cases of Heinz body anemia are due to the consumption of oxidising substances such as certain medications, toxins, and foods, some of which include:
- Allium species (onion, garlic, leek, chives, spring onion). Baby foods are a common source of onion and garlic toxicity in cats
- Acetaminophen (paracetamol)
- Propylene glycol (found in many products including soaps, shampoos, baby wipes and many types of processed food, including some types of semi-moist cat food)
- Phenacetin (painkiller)
- Methylene blue (urinary analgesic)
- Benzocaine (a local anesthetic)
- Naphthalene (mothballs)
- Vitamin K
- Zinc
Systemic disorders can also lead to the formation of Heinz bodies, including:
- Ketoacidosis: A serious complication of diabetes in which ketones and blood sugar levels build up in the body due to insufficient levels of insulin which is required to move glucose into the cells for energy. As a result, the body uses fat as an alternate energy source which produces ketones causing the blood to become too acidic.
- Hyperthyroidism
- Lymphoma
Clinical signs
Heinz bodies appear within 24 hours of exposure to the agent, however, there can be a lag of up to several days between ingestion and onset of symptoms. Severity depends on the amount of oxidant consumed as well as the duration of exposure. Heinz bodies tend to be produced at a slower rate by diet and disease compared to ingestion of drugs.
- Lethargy
- Anorexia
- Abdominal pain
- Yellow tinged membranes if jaundice is present
- Tachypnea (rapid breathing)
- Increased heart rate
- Red or brown urine and cyanotic (blue/grey tinged) or brown membranes if methemoglobinemia is present
- Hypersalivation
- Weakness
- Gastrointestinal disturbances such as abdominal pain, diarrhea, and vomiting.
We lost a kitten to this condition several years ago and his main symptoms were lethargy (the day before we realised he was sick), yellow gums (jaundice) and collapse.
If the underlying cause is due to systemic disease, there may be additional symptoms.
- Diabetes: Increased thirst and urination, weight loss, weakness in the hind legs, fruity breath.
- Hyperthyroidism: Increased appetite, weight loss, jittery behaviour, rapid heartbeat.
- Lymphoma: Symptoms can vary depending on the location but may include enlarged lymph nodes, anorexia, weight loss, and fever.
Diagnosis
The veterinarian will perform a complete physical examination of your cat and obtain a medical history from you including recent foods your cat may have eaten, medications or other household products he may have had exposure to.
Diagnostic workup:
- Baseline tests: Biochemical profile to evaluate organ function, complete blood count and urinalysis. CBC may reveal a reduced number of red blood cells, additional findings may vary depending on the underlying cause.
- Blood smear: Detection of Heinz bodies in blood smears stained with methylene blue. Note: Cats can have Heinz bodies in their red blood cells without having anemia.
- Abdominal radiographs: To look for metal objects if zinc toxicity is suspected.
If Heinz bodies are found but your cat has no history of ingestion (food, toxin, drug) it will be necessary for your veterinarian to look for an underlying cause such as systemic disease, in which case additional diagnostics will be necessary.
- Diabetes: Blood and urine tests to look for high levels of glucose (hyperglycemia and glucosuria).
- Hyperthyroidism: Blood tests to check levels of T3 and T4 hormones in the blood.
- Lymphoma: Chest and abdominal radiography to look for thickening of the intestines or masses. Biopsy or fine needle aspirate may be taken from tissues and bone marrow.
Treatment
The goal of treatment is to address the underlying cause as well as supportive therapy.
Cats with severe anemia will be hospitalised and receive blood transfusions and oxygen therapy.
IV fluids therapy for cats who have severe vomiting and/or diarrhea and to protect the kidneys against hemoglobin-induced injury.
Follow-up appointments will be necessary to assess red blood cell regeneration.
Prevention
- Always read food labels carefully and avoid any products containing onion, garlic or members of the Allium family.
- Dispose of food carefully.
- Never administer medications unless your veterinarian has told you to do so. Cats are not small people or dogs and are unable to metabolise many medications.
- Keep zinc-containing products locked away.
- Avoid the use of mothballs in the home.
- Don’t use lotions (such as sunscreen) containing zinc, which is easy to lick off.
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