MCH (mean cell hemoglobin) in cats and dogs
MCH (mean cell hemoglobin, also mean corpuscular hemoglobin) is the average amount of hemoglobin carried by one red blood cell. It is a calculated index that largely follows cell size, so vets usually read it as a check on MCV and MCHC rather than as a finding of its own.
What it shows
The analyzer does not measure MCH directly. It divides the hemoglobin concentration by the red cell count and reports how much hemoglobin, by weight, falls on an average cell.
The catch is that this amount depends on the size of the cell. A large red cell holds more hemoglobin simply because it is large, and a small one holds less, even when the cells are filled to the usual concentration. That is why eClinPath points out that MCH depends on cell volume, and why, when describing anemia, vets usually refer to MCV (size) and MCHC (how densely the cell is filled) and leave MCH out of the classification. Think of MCH as the weight of a bag and MCHC as how tightly it is packed: a heavier bag may just be a bigger one.
Higher than reference — what it may be a sign of
- Large red cells — anything that raises MCV, such as young cells during a regenerative response or breed macrocytosis in poodles, tends to raise MCH with it.
- Hemolysis — when red cells burst in the tube or inside the vessels, the freed hemoglobin is still measured, but the broken cells are no longer counted. Hemoglobin per counted cell then comes out falsely high; in this situation MCH moves together with MCHC rather than with MCV.
- Lipemia — fatty plasma, for example in blood taken soon after a meal, makes measured hemoglobin falsely high, and with it MCH and MCHC.
Lower than reference
- Small red cells — anything that lowers MCV lowers MCH. The main example is iron deficiency, usually from chronic blood loss: the cells are both smaller and less filled. Liver disease with a portosystemic shunt is another cause of small cells.
- Breed and age — dogs of breeds with naturally small red cells, such as Akitas, and very young puppies and kittens have small cells, so their MCH can sit lower without disease.
On its own a low MCH with normal MCV and MCHC rarely changes the picture; the vet looks at the size and concentration indices first.
Look at together with
- MCV — if MCH changed together with MCV, the change is about cell size.
- MCHC — if MCH moved with MCHC while MCV did not, think about hemolysis or lipemia in the sample.
- Hemoglobin and red cell count — the two numbers MCH is calculated from.
- RDW and the blood smear — whether there is a mixed population of large and small cells.
Units and conversion
MCH is reported in picograms (pg; пг on Russian-language forms). A picogram is a trillionth of a gram (10⁻¹² g). Forms in different countries use the same unit, so there is nothing to convert: the factor is 1. In the app each row keeps the unit printed on the form.
Reference range
The reference range is on your lab’s form. It depends on species and on the analyzer, because cell size differs between cats and dogs. Because MCH is derived from two other measurements, any error in hemoglobin or in the red cell count passes straight into it. A value outside the range that disagrees with MCV and MCHC is first a reason to check the sample — for hemolysis or lipemia — and to look at the trend over several tests.
Cats and dogs
The sources describe no separate feline rules for MCH: it is read the same way as in dogs, alongside MCV and MCHC. In cats it is worth remembering the sample effects — lipemia after a meal and hemolysis — which raise MCH together with MCHC, and the post-regenerative period, when large young red cells can stay in the blood for weeks and keep MCV, and with it MCH, high.
In dogs MCH mostly mirrors cell size, so breed shows through it: poodles with naturally large red cells can have a higher MCH, Akitas with small red cells a lower one, without anemia. Iron deficiency from chronic blood loss is the usual disease behind a combined drop in MCV and MCH.
Add a lab form — Pet Tracker Space recognises the lines, keeps the form’s units and draws each indicator over time with your lab’s reference band.
Sources
This page explains what a lab value means. It is not a diagnosis and not a substitute for your veterinarian — only they can interpret results for your pet.