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 (known as hemolysis).
Cats are at greater risk of Heinz body anemia than other animals. 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.
A second type of oxidative damage may also occur. Methemoglobinemia is 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.
There are three types of anemia, blood loss, non-regenerative and regenerative. Non-regenerative anemia is due to a decrease in production of red blood cells from in the bone marrow, regenerative occurs when red blood cell production is normal however they are destroyed faster than they can be made, anemia from blood loss can be external (from a wound for example) or internal bleeding. 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.
There is no breed, sex or age disposition.
What causes Heinz body anemia?
There are a number of causes of Heinz body anemia which can affect cats. Most cases 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). These may be raw, cooked, powdered or dehydrated.
- 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 (moth balls).
- Vitamin K.
Systemic disorders can also lead to the formation of Heinz bodies, including:
What are the symptoms of Heinz body anemia?
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.
- 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.
- 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, bad breath.
- Hyperthyroidism: Increased appetite, weight loss, jittery behavior, rapid heartbeat.
- Lymphoma: Symptoms can vary depending on the location but may include enlarged lymph nodes, anorexia, weight loss and fever.
How is Heinz body anemia diagnosed?
Your 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. He will need to perform some diagnostic tests including:
- Complete blood count, biochemical profile, and urinalysis.
- Detection of Heinz bodies in blood smears stained with methylene blue. It should be noted that 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. He may need to run the following tests:
- 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 hormone 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.
How is Heinz body anemia treated?
Treatment depends on the severity of anemia, minor cases may require no treatment at all.
If your cat has recently ingested a toxin or product containing onion, garlic etc., then the decontamination of the stomach contents and/or activated charcoal administered. Inducing emesis (vomiting) may be carried out on cats with known exposure but who are not displaying symptoms.
Severely anemic cats may require a blood transfusion and/or oxygen therapy.
Fluid therapy may be required for cats who have severe vomiting and/or diarrhea and to protect the kidneys against hemoglobin-induced injury.
Endoscopy or surgery to remove metal objects from the gastrointestinal tract to treat zinc toxicity.
Anti-oxidants such as N-acetylcysteine (NAC). This amino acid assists in the detoxification and elimination of toxins.
Other treatments will be required to address systemic diseases such as hyperthyroidism, diabetes, and lymphoma.
Your cat should be placed on restricted activity while he recuperates.
Follow up appointments will be necessary to assess red blood cell regeneration.
Preventing Heinz body anemia in cats:
- 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. Many well-meaning pet owners administer over the counter painkillers to cats thinking they are doing the right thing, but cats process these drugs differently to us and even small doses can be fatal.
- Keep zinc-containing products locked away.
- Avoid the use of mothballs in the home.
- Don't use lotions (such as sunscreen) containing zinc. This can be easily licked off.
Heinz body blood sample photo courtesy of Nottingham Vet School.
In memory of Shadow.