By The Pawline veterinary teamVeterinary-reviewed by Alastair Greenway, BVM&S MRCVS · 25 July 2026
Reference range · g/dL
1218
Reference
12–18
Direction
Both unusually high and low values carry meaning.
This is the conventional reference interval. Your pet’s own report may print a slightly different range — always read the value against that. Sign in to see your pet’s value on this strip.
Haemoglobin is the oxygen-carrying pigment packed inside red blood cells, and it tracks closely with the haematocrit. Together they describe how well the blood is carrying oxygen, so a low haemoglobin is essentially another way of measuring anaemia.
Haemoglobin (HGB) is the iron-containing pigment inside red blood cells that actually does the work of carrying oxygen — binding it in the lungs and releasing it to the tissues. While the haematocrit measures the proportion of blood that is red cells, haemoglobin measures the amount of oxygen-carrying pigment directly. The two move together and tell a very similar story, which is why they are almost always read side by side.
Haemoglobin is the oxygen-carrying pigment inside red cells. It tracks with haematocrit and, together, they measure oxygen-carrying capacity.
Because it measures the pigment itself, haemoglobin is in one sense the most direct measure of the blood's oxygen-carrying capacity.
Reading a low result
A low haemoglobin means anaemia — reduced oxygen-carrying capacity — and it moves in step with a low haematocrit. The causes and the work-up are the same as for haematocrit: blood loss, red-cell destruction (haemolysis), or reduced production, sorted out with the reticulocyte count and the clinical picture. Occasionally haemoglobin and haematocrit disagree slightly, and that mismatch can itself be a clue — for example, free haemoglobin released by red-cell destruction can nudge the measured haemoglobin, which is one reason both numbers are reported.
Reading a high result
A high haemoglobin, like a high haematocrit, most commonly reflects dehydration (concentration of the blood) and corrects with fluids; a genuinely raised red-cell mass (polycythaemia) is the less common alternative that needs specific investigation. As always, hydration is assessed first.
In chronic disease
Haemoglobin is tracked alongside haematocrit to follow anaemia in chronic disease — the slow decline seen in chronic kidney disease and chronic inflammation, and the recovery that signals treatment is working. Because it is a direct measure of oxygen-carrying pigment, it is a useful number for judging how much an anaemia is likely to be affecting the pet.
Cat vs dog
Haemoglobin is interpreted the same way in both species, running lower in cats than dogs in parallel with their lower haematocrit. It is always read together with haematocrit and the red-cell indices (MCV, MCH, MCHC), which use haemoglobin and cell size to characterise what kind of anaemia is present. Feline-specific rules apply when judging the marrow's regenerative response.
How it's measured
Haemoglobin is measured directly by the analyser as part of the CBC, reported in g/dL (US) or g/L (UK/SI). It is read alongside haematocrit, the red cell count, the indices and the reticulocyte count. A haemolysed or lipaemic sample can affect the reading, so clean collection matters. Read the value against your own report's range.
What to do next
Because haemoglobin and haematocrit tell the same story, a low haemoglobin is worked up as anaemia — the reticulocyte count to judge regeneration, and a search for loss, destruction or a production problem. In chronic disease, follow the trend with your vet; a recovering haemoglobin is tangible evidence the blood is rebuilding its oxygen-carrying capacity.
Reference ranges reflect conventional laboratory intervals. Always interpret against your own lab's printed range and your veterinary surgeon's judgement. A brighter optimal band is shown only where a published guideline defines one, and it is cited.
This page is educational and is not a diagnosis. Lab results are interpreted in the full clinical context by your veterinary surgeon; a single value rarely tells the whole story.
