Myelodysplasia in Cats: Causes, Symptoms and Treatment

Myelodysplasia, also known as aplastic anaemia, is a serious condition that disrupts the production of essential blood cells in a cat’s bone marrow. Normally, a healthy cat’s bone marrow releases around three million red blood cells into the bloodstream every second. When myelodysplasia occurs, the bone marrow cannot replenish these cells fast enough, leading to a shortage of red blood cells, white blood cells, and platelets, with potentially severe consequences for the cat’s health.

The Causes of Myelodysplasia in Cats

This condition can stem from various causes, often involving the infiltration of fatty tissues called adipose, which restrict the bone marrow's ability to produce enough blood cells. A deficiency in red blood cells means oxygen delivery and carbon dioxide removal from the body become impaired. Low white blood cell levels compromise the cat’s immune defences, increasing vulnerability to infections. A shortage of platelets affects blood clotting, raising the risk of internal and external bleeding.

Common contributing factors include:

• Infections such as feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV)
• Feline parvovirus infection
• Rickettsial infections (e.g., ehrlichia)
• Certain medications including antibiotics, non-steroidal anti-inflammatory drugs (NSAIDs), chemotherapy drugs, and oestrogen supplements
• Exposure to harmful chemicals or radiation therapy

Symptoms - What to Watch For

The clinical signs of myelodysplasia vary depending on which blood cells are most depleted. Key symptoms to monitor include:

• Recurring or persistent infections that are difficult to resolve
• Fever or elevated body temperature
• Red or purple spots on the skin caused by small haemorrhages
• Blood in the urine (haematuria)
• Nosebleeds (epistaxis)
• Black, tarry stools indicating gastrointestinal bleeding
• Pale gums suggesting anaemia
• Weakness and lethargy

Diagnosing Myelodysplasia

A thorough veterinary evaluation is essential. The vet will collect a full medical history and clarify when symptoms began. Diagnostic tests typically include:

• Complete blood count to evaluate red, white blood cells, and platelets
• Biochemical blood profile
• Urinalysis
• Bone marrow biopsy or aspiration to assess cell production and identify abnormalities

These tests help rule out other diseases and confirm the diagnosis of myelodysplasia.

Treatment and Support Care

Following diagnosis, your vet will develop a treatment plan tailored to your cat’s specific needs. Initial care often requires hospitalisation for close monitoring. Treatment may include:

• Blood transfusions to manage severe anaemia
• Antibiotic therapy to combat and prevent infections
• Supportive care such as fluids and nutritional support
• In some cases, chemotherapy agents like azacytidine may be considered under specialist care

Managing Your Cat’s Condition

Cats with myelodysplasia require ongoing veterinary visits to monitor blood parameters and bone marrow status. Repeated bone marrow sampling helps evaluate response to treatment. Patience and diligent care are vital as treatment can extend over several months.

Prognosis and Outlook

Unfortunately, the prognosis for cats with myelodysplasia is guarded to poor, with many cats unable to survive despite comprehensive treatment. Younger cats tend to have a better chance of survival, although treatment may be prolonged. Discussing your cat’s condition and care goals with your vet is important for making informed decisions.

Summary

Myelodysplasia in cats is a serious bone marrow disorder that reduces vital blood cell production. Recognising symptoms early and obtaining timely veterinary diagnosis are crucial. While treatment options exist, managing expectations around prognosis and providing compassionate care are key parts of supporting affected cats.

For more information on keeping your cat healthy, consider consulting with your veterinary practice and accessing reliable feline health resources.