Anaemia

Anaemia refers to a deficiency in red blood cells and/or haemoglobin in the blood. Red blood cells are produced by the bone marrow and released into the bloodstream where they carry oxygen around the body. Once they die or become damaged they are removed from the bloodstream and broken down in the spleen, liver and lymph nodes. Red blood cells are rich in haemoglobin. Haemoglobin is a bio-molecule that binds oxygen for transport around the body.

The most easily recognisable symptom of anaemia is pale gums. Healthy cats have pale-pink pink gums whereas cats suffering from anaemia usually have very pale pink to white gums. Anaemic cats also tend to suffer from lethargy and will tire easily from normal activity. Cats with severe anaemia may present with a rapid heartbeat or breathing rate as the body attempts to compensate for the lack of oxygen getting to tissues in the body. Depending on the cause of the anaemia other clinical signs may be present such as abdominal pain and a high temperature.

There are three main processes which can lead to anaemia:

• Increased loss of red blood cells
• Increased destruction of red blood cells
• Reduced production of red blood cells

Increased loss of red blood cells can be a result of:

• trauma causing blood loss
• internal tumours which bleed or cause bleeding e.g. intestinal tumours bleeding into the intestines
• other conditions causing bleeding e.g. stomach ulcers
• severe parasitic infections with blood-consuming parasites
• blood clotting disorders resulting in increased blood loss

Increased destruction of red blood cells can be a result of:

• autoimmune disease (where the immune system attacks the body's own red blood cells)
• feline infectious anaemia caused by a blood parasite called Mycoplasma haemofelis
• feline leukaemia virus (FeLV)
• ingestion of, or exposure to, certain drugs or toxins e.g. paracetamol
• certain types of cancer

Reduced production of red blood cells can be a result of:

• systemic disease such as chronic kidney disease or liver disease
• inflammatory disease e.g. infections
• autoimmune disease where the immune system attacks the body
• feline leukaemia virus (FeLV)
• feline immunodeficiency virus (FIV)
• ingestion of, or exposure to, certain drugs or toxins e.g. as a rare side effect of medication to treat hyperthyroidism
• certain types of cancer e.g. leukaemia
• nutritional deficiency or imbalance

Anaemia is diagnosed via a blood test. Your vet will be able to perform a packed cell volume (PCV) to look at the percentage of red blood cells in your cat's blood. If the PCV is below 26% this confirms a diagnosis of anaemia. The PCV score will help determine the severity of the anaemia from mild to severe. This is useful as it will give your vet a clue as to the cause of the anaemia, for example, anaemia caused by systemic disease is more likely to be mild compared to anaemia as a result of haemorrhage.

Your vet will also be able to determine if the anaemia is regenerative or non-regenerative. If your cat is suffering from regenerative anaemia, this means that the bone marrow is producing an increased number of red blood cells to account for the red blood cell loss. In this case, the bone marrow will release greater numbers of immature red blood cells, called reticulocytes, into the bloodstream. The reticulocytes can be counted under a microscope or automatically by a blood machine. The reticulocyte count will also give your vet a clue to the cause of the anaemia. For example internal haemorrhage and immune-mediated destruction of the red blood cells are most likely to result in regenerative anaemias.

Your vet will want to perform further tests to diagnose the cause of the anaemia such as further blood or urine tests e.g. to check for signs of kidney disease; imaging of the abdomen (x-rays or ultrasound) to check for internal bleeding; or a bone marrow aspirate or biopsy to check for conditions affecting the bone marrow.

If your cat’s anaemia is severe and life-threatening they will require a blood transfusion. Samples of your cat’s blood will need to be taken for blood typing before the transfusion takes place. This will not cure the anaemia, it acts to stabilise the body whilst the cause of the anaemia is diagnosed and treated.

Treatment will need to be directed at the cause of the anaemia and so treatment options will vary. Internal bleeding or tumours of the abdominal organs can sometimes be treated surgically. Other diseases can be treated with certain types of medication for example immune-mediated disease is treated with immune-suppressing medications (usually corticosteroids), feline infectious anaemia is treated with a certain type of antibiotic, and there are a range of medications and diets that can support cats with kidney or liver disease. Treatment of cats with FeLV or FIV infection is focused on supportive care.