Anaemia in pets

What It Is

Anaemia means a lower than normal number of red blood cells, the cells that carry oxygen around the body. It is usually picked up on routine bloodwork or suspected from pale gums, tiredness, or a fast heart rate, and it is a finding that points to an underlying problem rather than a disease in itself. Anaemia is described as regenerative, when the bone marrow is actively trying to replace lost cells, or non-regenerative, when the marrow is not responding, and this distinction guides what tests come next.

Common Causes

Blood loss from injury, ulcers, parasites such as fleas or intestinal worms, or a bleeding tumour is a common and often regenerative cause. Immune-mediated disease, where the body destroys its own red blood cells, is a serious and sometimes rapidly progressing cause seen in both dogs and cats. Chronic kidney disease reduces the hormone that signals the marrow to make new red cells, leading to a slow, non-regenerative anaemia common in older cats. Certain infections, toxins, and cancers affecting the bone marrow itself are less common but important causes to rule out.

When It Is an Emergency

Anaemia paired with weakness, collapse, very pale or white gums, a fast heart rate, or laboured breathing is an emergency and needs immediate veterinary care. If your vet has just told you bloodwork shows anaemia and your pet is stable, bright, and eating, urgent same-day treatment may not be needed, but follow-up testing to find the cause should not be delayed. Anaemia can worsen quickly with some causes, so any sudden change in energy or breathing after diagnosis warrants an immediate call.

What the Vet Will Do

Further bloodwork typically follows an initial anaemia finding, looking at red cell shape and the marrow's response to identify whether it is regenerative or not. Tests for parasites, tick-borne disease, immune markers, and organ function help narrow down the cause. Imaging such as ultrasound or X-rays looks for internal bleeding or tumours. In more severe cases, a bone marrow sample may be needed. Some pets need a blood transfusion to stabilise them while the underlying cause is treated.

Home Care and Prevention

Regular parasite prevention lowers the risk of blood-loss anaemia from fleas, ticks, and intestinal worms. Routine bloodwork in older pets, especially cats, can catch chronic kidney disease and its associated anaemia early. Once a cause is identified, following the prescribed treatment and recheck schedule closely is the best way to prevent the anaemia from worsening or recurring.