Picture this: It’s a Friday afternoon (of course!), you’re on the inpatient shift,
and you get a call from reception for advice.

A 3-year-old Springer Spaniel has collapsed at home and is tachypnoeic, weak, and jaundiced. You tell them to come straight down and then start getting ready to triage and stabilise them.

We’ve all been there, right? But before we call the blood bank and panic about transfusions, we need to also consider what’s going on with our patients and how we can use our understanding of this to plan their nursing care. 

Anaemia is probably the most common haematologic disease we see, so it’s vital that we understand why it occurs, how it affects our patients, and what we need to do when nursing these patients.

In episode 40 of the Medical Nursing Podcast, we’re going to talk all about anaemia. We’ll chat about how we classify it, what changes we see in our results, and how we treat these patients - so you can provide the best possible nursing care.

So, what is anaemia?

We can define anaemia as:

• A decrease in packed cell volume (PCV) or haematocrit (HCT)

• A decrease in red blood cell concentration 

• A decrease in haemoglobin concentration

It’s considered a secondary condition—i.e., a consequence of an underlying disease—rather than a primary or idiopathic condition. There are many different causes, which can be classified in several ways—by the underlying cause, by the bone marrow’s response to the anaemia, and by the size and shape of the red blood cells.

Ok, so we know what anaemia is - but what causes it?

Really, all anaemias boil down to one of three causes - lack of production, destruction, or loss.

A lack of RBC production (aka aplastic anaemia) occurs when the bone marrow fails to create new red blood cells. Normally, the spleen removes mature RBCs, and the bone marrow replaces them with reticulocytes (immature RBCs that then mature in the bloodstream).

If a primary bone marrow disease or neoplasia (e.g., leukaemia) affects the bone marrow, the bone marrow can’t do its job, and our patients end up anaemic.

Destruction is a common cause of anaemia and occurs when there is haemolysis - red blood cell breakdown. Immune-mediated haemolytic anaemia (IMHA) is a classic example of this. These patients can make new RBCs as their bone marrow works normally, but something in the body (the immune system in IMHA cases) is destroying those cells.

The last cause of anaemia is haemorrhage - whole blood loss, for example, in trauma patients or during surgery.

Patients can present with anaemia due to one or a combination of these three causes. For example, patients with Evans syndrome have a combination of immune-mediated thrombocytopenia and haemolytic anaemia, where the immune system destroys red blood cells and platelets. Commonly, these patients have RBC destruction and haemorrhage because their thrombocytopenia causes bleeding.

What changes do we see in our haematology?

In addition to a low PCV, haematocrit and RBC level, we can also classify our patient’s anaemia based on our haematology results - specifically, by the size and haemoglobin concentration of the red blood cells:

• The mean corpuscular volume (MCV) tells us about the size of our RBCs

• The mean corpuscular haemoglobin concentration (MCHC) tells us about the cells’ iron content and oxygen-carrying capability. 

Depending on the MCV and MCHC levels, we can classify our anaemias as normocytic, microcytic, normochromic, or hypochromic. Each type of anaemia has different causes, so this is particularly useful in helping us narrow down the patient’s differential diagnoses.

• Normocytic anaemia occurs when the RBCs are normal in size. There are many causes of normocytic anaemia, but it is commonly seen in cases of regenerative anaemia.

• Microcytic anaemia is a condition in which the RBCs are small. It is generally associated with iron deficiency, as RBC division increases when insufficient iron is present, resulting in smaller cells.

• Hypochromic anaemia is where MCHC is low. It is commonly seen in cases of iron deficiency. 

• Normochromic anaemia is anaemia with a normal MCHC. We see normochromic anaemia for a wide variety of reasons.

What about regeneration?

Anaemia can also be categorised as non-regenerative or regenerative, depending on whether new red blood cells are released.

Figuring out whether the anaemia is regenerative is an essential step in investigating anaemia. It allows us to refine our list of differential diagnoses and guides further tests and treatments.

Regenerative anaemia

Regenerative anaemia is caused by haemorrhage or haemolysis and is assessed by the presence of polychromasia, which is an increase in reticulocytes (aka polychromatophils—our baby RBCs). 

Polychromasia can be seen on a blood film examination, and reticulocyte levels can be counted on a haematology analyser.

On microscopic examination, polychromatophils are larger than mature red blood cells and do not contain as much haemoglobin. This means they don’t absorb as much diff-quick stain and appear a lighter purple colour.

In dogs and cats, reticulocyte levels will increase after 2-5 days (depending on species) after red blood cell loss, reaching peak levels within 7-10 days. 

Erythropoietin kicks off this process. This hormone is released from the kidneys after anaemia causes a reduction in circulating oxygen levels. 

The erythropoietin stimulates the bone marrow to produce more red blood cells, causing an increase in reticulocytes released into the bloodstream. 

This process takes a few days, so pre-regenerative anaemia may be seen if the patient presents to the clinic early enough. These patients appear to have a non-regenerative anaemia, but in actual fact, the body has just not had enough time to release those reticulocytes yet.

Immune-mediated haemolytic anaemia is a regenerative anaemia caused by antibody-mediated destruction of red blood cells.

Non-regenerative anaemia

In cases of non-regenerative (aka aplastic) anaemia, reticulocyte levels do not increase. This means that a mature population of red blood cells is seen, which are not being replaced by immature cells. When these mature cells die, the patient is left with insufficient RBCs.

Aplastic anaemia can be primary or secondary: 

• Primary aplastic anaemia is an immune-mediated condition where the immune system attacks red blood cell precursor cells within the bone marrow. 

• Secondary aplastic anaemia can occur for various reasons, including infectious diseases, reactions to toxins and certain medications, such as immunosuppressive and cytotoxic agents. 

Okay, so that’s what anaemia is and what causes it—but how are we going to stabilise our anaemic patient?

Anaemia is often a medical emergency. These patients can present to the clinic with severe shock as circulating volume reduces, hypovolaemia results and oxygen delivery to tissues is impaired secondary to red blood cell loss.

We must perform an immediate triage examination when the patient arrives at the clinic. 

This assessment should include an evaluation of the major body systems: the cardiovascular, respiratory, and neurological systems.

Once your initial triage assessment is complete, we need to prioritise intravenous catheterisation and appropriate fluid resuscitation under the direction of the veterinary surgeon. 

Supplemental oxygen should also be provided. This is important as a small amount of oxygen is transported dissolved in plasma, so this will continue even when there are fewer RBCs.

And how do we diagnose anaemia?

Many diagnostic tests are used to investigate anaemia. We use these to assess the severity of the patient’s anaemia and to understand the underlying cause. We also perform tests to prepare the patient for blood transfusions, where this is required.

Common diagnostics include:

• Full haematology

• Blood smear examination

• PCV and total solids measurement

• Full biochemistry

• Infectious disease testing – e.g. FeLV/FIV in cats, 4Dx (tick-borne disease panel) in dogs

• Blood typing +/- cross-matching (where a transfusion is required)

• In-saline agglutination (+/- Coombs Test) to test for IMHA

• Abdominal ultrasound +/- thoracic X-ray to determine any underlying cause (e.g. neoplasia)

• Bone marrow aspirate and core biopsy to examine red blood cell precursor cells, if required.

We’ve diagnosed our patient - how do we treat them?

Treatment of anaemia is based on managing the underlying cause. Standard treatment options include:

• Blood product transfusion

• Immunosuppression

• Supportive treatment

• Managing the source of bleeding or controlling a coagulopathy

Blood product transfusion 

The patient should be transfused with a suitable type-matched blood product where required. 

The idea of transfusion medicine is to replace only what’s lost. This means that if you have a bleeding patient, whole blood is the most suitable replacement fluid.

Where red blood cells are destroyed or not produced, packed red blood cells are a more appropriate choice since the patient is only losing RBCs, not plasma or other blood components.

Immunosuppression

Immunosuppressive drugs are required in the management of IMHA. 

These typically include glucocorticoids (steroids) and, in severe cases, an additional second-line immunosuppressive agent. 

These medications have health and safety considerations and cause polyuria and polydipsia, so they should be handled with care, and the patient given regular toileting opportunities.

Supportive treatments

Supportive care may include the provision of:

• Supplemental oxygen

• Antithrombotic agents (since IMHA patients love to throw clots!)

• Analgesia

• Gastroprotectants,

• or other medications depending on the underlying cause of the anaemia.

Ok, that’s the treatment sorted - how will we nurse our anaemic patient?

There’s a LOT to think about regarding anaemic patient care.

In addition to general nursing care requirements, our patients will need:

• Intensive monitoring

• Blood product administration, monitoring

• Rest

• Minimal stress and exercise

Monitoring

The patient should receive regular clinical assessments, particularly parameters such as heart rate, pulse quality, blood pressure, mucous membrane colour, capillary refill time, and evaluation of mentation and temperature, to assess perfusion status. 

The frequency of these observations should be tailored to the individual patient and the severity of their disease.

Blood product transfusion

Patients requiring blood product transfusions require intensive nursing monitoring for the duration of their transfusion (typically 4-6 hours), to identify any transfusion reaction. 

TPRs, blood pressure, mucous membrane, and CRT assessments should be repeated every 10 minutes for the first 30 minutes of the transfusion, then reduced to every 15-30 minutes until the transfusion is completed.

We’re talking all about transfusions in a separate episode, so that’s coming up later in this series!

Prioritising rest and sleep

Anaemic patients can tire quickly and have a lower tolerance for handling, procedures and exercise. This is because they have a reduced oxygen-carrying capacity compared with healthy patients!

We must consider this when planning nursing care and scheduling treatment times to maximise rest and sleep between periods of patient contact. 

'Lights-off' time should be provided to facilitate rest and keep the patient calm.

Fluid balance

We need to regularly assess our patients’ volume and hydration status and administer appropriate fluid therapy. 

Remember—fluids are drugs, and they have risks and considerations just like any other medication! So, monitoring for signs of overload or insufficient administration is a vital aspect of our care.

In addition, intravenous catheters should be regularly checked for signs of phlebitis, flushed, and re-bandaged at least twice daily.

So that’s a brief overview of why anaemia occurs, how we classify and diagnose different causes of anaemia, and how we nurse these patients! 

I’d love to hear what comes up for you as you listen to today’s episode! DM me on Instagram and let me know—I can’t wait to hear from you! In the meantime, have a great week, and I’ll see you next time when we’re chatting more about nursing our haematology patients.

References and Further Reading

• Day, MJ and Kohn, B. 2012. BSAVA Manual of Canine and Feline Haematology and Transfusion Medicine. 2nd ed. Gloucester: BSAVA.

• EClinPath. 2013. Haematology [Available from: http://eclinpath.com/hematology/].

• Merrill, L. 2012. Small Animal Internal Medicine for Veterinary Technicians and Nurses. 1st ed. Iowa: Wiley-Blackwell.

• Sirois, M. 2020. Laboratory Procedures for Veterinary Technicians. 7th edition. Missouri: Elsevier.