The Anemic Pet

Anemia is not a disease but, instead, refers to a decrease in the number of circulating red blood cells (RBC), hemoglobin (Hb), or both.

I’m sure you’re aware, that having an appropriate number of RBCs with a good amount of hemoglobin (to carry oxygen) is integral for the body to function properly. When we don’t have enough, it can be detrimental!

When a pet is anemic, one of the most common and obvious clinical signs you will see is a loss of the normal pink colour of the gums. However, they can present with a wide array of signs depending on the cause of the anemia and if it has come on quickly (acute) or been an on-going issue (chronic) that the pet has been dealing with.

Pets may also show moderate to severe lethargy, laboured breathing (dyspnea/tachypnea), loss of appetite (anorexia), increased heart rate (tachycardia), and/or blood loss (external wounds, nose, urine, feces, vomit).

So, you’ve stabilized your patient (if needed) and you suspect he/she is anemic. What do you do next?


Sampling blood to look at your packed cell volume (PCV) and hematocrit (HCT) is going to be the quickest way we can confirm or rule out anemia in a patient.

Now, we know our patient is anemic… but, where is the anemia coming from?

Since anemia can be caused by a multitude of different disease, I try to simplify my thought process by thinking of the 4 H’s to help me figure out where to go next.

  1. Hemorrhage: this is caused by external wounds or bleeding into a body cavity (abdomen, thorax, GI tract, bladder, etc). Internal bleeding can be caused by trauma, bleeding tumours, blood clotting disorders (coagulopathies), etc.

  2. Hemolysis: something is causing the RBC to rupture inside the vessels (intravascular) or outside the vessels/in an organ (extravascular). This can be caused by the immune system attacking RBC inappropriately (immune mediated, neoplastic), turbulent blood flow b/c of vessel pathology (microangiopathic hemolysis), electrolyte imbalance (hypophosphotemia), ingested toxins (heavy metals, plants, some human medications, etc.), infections (Ehrlichia, mycoplasma hemofelis, etc.),and/or allergic reaction (type II sensitivity reaction).

  3. Hypoplasia: the body is not producing enough red blood cells. This can be do to the bone marrow not functioning properly to produce RBC because of an infection (parvovirus, etc.), a drug reaction, toxin ingestion, neoplasia (leukaemia), or an issue with the bone marrow inherently (myelodysplasia, myelofibrosis). The kidneys also play a large role in making RBC by producing the hormone erythopoieitin. If the kidneys have severe disease, this can have an impact on RBC production. Finally, malnutrition or not having enough/the right nutrients can cause anemia.

  4. Hemodilution: this is not a true anemia because it is caused by decreased concentration of RBC in the blood usually because of over hydration with IV fluids.

Once you ensure your patient is stable, gather a thorough history, do a comprehensive physical exam, and sample the blood to confirm anemia, then you can start narrowing down your differential list by doing the most necessary diagnostics based on the information you have gathered. Depending on the case, this might be full bloodwork, radiographs, ultrasound, bone marrow aspirate, etc.

Do you have any tips or tricks when dealing with anemic patients?

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