High MCH and High MCHC in Dogs – What the Pattern Means

High MCH and High MCHC in Dogs – What the Pattern Means

Wondering what a full interpretation looks like? See a sample report →

Why a “High” Result Here Is Usually a Clue, Not a Disease

Most blood values invite the question “what condition pushed this up?” MCH and MCHC are different, and understanding why changes how the whole result is read. MCH is the average mass of hemoglobin inside one red cell, and MCHC is how concentrated that hemoglobin is within the cell. The key physiological fact is that a red cell can only hold so much hemoglobin before it is, in effect, full – there is no biological mechanism that lets a dog’s cells become genuinely over-packed. That single constraint is why a markedly high MCHC is treated with suspicion rather than alarm: if the value cannot really be that high, then something must be distorting the measurement. The job of the rest of the workup is to find what, and the answer is usually mundane and fixable rather than a serious disease of the blood. For a plain-language tour of where these indices sit in the larger picture, the overview of dog blood work explained across the CBC and chemistry panel is a helpful companion to this article.

How Hemolysis and Lipemia Fool the Analyser

The two usual explanations for a high MCH and MCHC in dogs are hemolysis and lipemia, and both work by inflating the measured hemoglobin. In hemolysis, red cells rupture and release their hemoglobin into the surrounding plasma. This can occur inside the body, but it happens far more commonly to the sample itself – during a difficult blood draw, with rough handling, or with delays before processing. The analyser still counts that freed hemoglobin, so when it divides hemoglobin by the cells that are left, the calculated concentration reads too high. Lipemia does something similar by a different route: fat suspended in the blood scatters light inside the instrument, and because hemoglobin is read optically, the machine interprets the cloudiness as extra hemoglobin. Either way, the indices that depend on hemoglobin – MCH and MCHC – drift upward without any real change in the dog’s red cells. Recognising this is what separates a measurement quirk from a true abnormality, the same kind of distinction your veterinarian makes when reading a complete dog blood test report step by step.

What MCH and MCHC Actually Measure

These are calculated indices, not directly measured ones. The analyser measures the hemoglobin, the red cell count and the packed cell volume, then derives MCH and MCHC from them. That is precisely why a problem with the hemoglobin reading – from hemolysis or lipemia – flows straight through into both indices. Reference intervals depend on the analyser and method, so your own dog’s report range is always the final word. As an evidence-based guide, the verified canine intervals are listed below alongside the related red-cell values that your veterinarian reads in the same breath, because no single index is interpreted alone.

See the full reference intervals for the dog — every value cited to the laboratory document or paper it came from.

The Smear Settles the Argument

When the indices look impossibly high, the blood smear is the tool that explains why. A drop of blood reviewed under the microscope shows whether the plasma looks pink-tinged from freed hemoglobin, whether the sample is cloudy with fat, and whether the red cells themselves look normal in size and colour. The analyser also flags the sample with quality indices for hemolysis and lipemia, so the machine and the microscope tell a consistent story. The table below maps the common reasons these indices climb to the way a veterinarian sorts them out.

Reading These Indices Alongside the Rest of the Count

Because MCH and MCHC are derived numbers, they earn their meaning only next to the values they are built from. If the hematocrit, red cell count and hemoglobin all hang together sensibly and the dog is well, an isolated high MCHC is easy to dismiss as artifact. The picture changes when other red-cell numbers are off too – for instance when the proportions between cell count and packed volume do not match, as discussed in high hematocrit with a low RBC count, or when both are raised together as in high hematocrit and high RBC. In an older dog with several mild abnormalities at once, your veterinarian weighs the indices against the whole pattern, which is the spirit of reviewing common senior-dog CBC abnormalities. The point is consistent: a lone high MCHC almost always loses its drama once the rest of the count is in view, and the question of whether it is worrying at all is one this article shares with does a high MCH always mean trouble in dogs.

When the High Side Is Artifact but the Low Side Matters

It is worth knowing that these indices are read asymmetrically. A high MCH or MCHC usually points toward artifact, but a low result is the side that carries genuine clinical information. A low MCHC – hypochromia, meaning red cells that are paler than they should be – is associated with regenerative anemia and with iron-deficiency anemia, and a low MCH likewise tends to accompany iron deficiency. That is the opposite direction from the topic of this article, and it is why your veterinarian does not simply ignore the indices: the same numbers that mean little when high can be a real signpost when low. Anemia in some breeds deserves a careful look on its own terms, as covered in anemia in large-breed dogs and what a low HCT really means. None of this is something an owner can track at home; these are laboratory indices interpreted by the analyser and the clinician together, not values to monitor between visits.

When to Pick Up the Phone

The indices themselves rarely drive urgency – the dog’s condition does. A bright, comfortable dog whose only oddity is a high MCHC almost certainly has a sample artifact, and a calm recheck is the sensible path. Concern rises when the high indices sit alongside genuine signs of illness: pale or yellow-tinged gums, unusual tiredness, dark urine, or collapse, any of which can point toward true hemolysis happening inside the dog rather than in the tube. In that setting your veterinarian reads the indices alongside the whole count – looking for anemia, an appropriate reticulocyte response, and changes such as those seen with a high total bilirubin from hemolysis. Other conditions that disturb the blood count, such as low platelets from immune-mediated disease or the changes seen with high cortisol in Cushing’s disease versus a stress response, are sorted out in the same way – by the pattern, not by one index. There is no home treatment for these values; the appropriate action is a veterinary recheck and, where indicated, a repeat sample, with the threshold for emergency care set by how the dog looks and feels. The companion piece on critical MCHC levels and emergency signs in dogs walks through where that line falls.