GRA (granulocytes) in cats and dogs
GRA (granulocytes) is one of three white cell lines — LYM, MID and GRA — that forms from many clinic analyzers print instead of the full five-type breakdown; how the cells are divided between the lines is decided by the analyzer itself. By name it covers neutrophils, eosinophils and basophils; because neutrophils outnumber the other white cells in healthy cats and dogs, GRA mostly follows them.
What it shows
A full differential splits white cells into five types: neutrophils, lymphocytes, monocytes, eosinophils and basophils. Forms from many clinic analyzers have three lines instead: lymphocytes (LYM), mid-sized cells (MID) and granulocytes (GRA). Analyzers that work on the impedance principle count cells as they pass through a tiny opening, and the size of the electrical pulse each cell makes reflects its size; a breakdown built this way sorts cells by how the machine sees them, not by how they look under a microscope.
Granulocytes are the white cells with granules in their cytoplasm — neutrophils, eosinophils and basophils. In healthy cats and dogs neutrophils outnumber the others, so in most cases a change in GRA is a change in neutrophils. Think of GRA as a box labelled “granulocytes” that the machine fills by size: it is a useful rough figure, but not the same thing as a neutrophil count from a smear.
Higher than reference — what it may be a sign of
- Inflammation, infectious or not — together with stress hormones, one of the most common reasons for more neutrophils.
- Stress and excitement — the body’s own cortisol and adrenaline, or steroid medicines, raise neutrophils; a frightened animal at the clinic can show this without disease.
- More eosinophils — parasites (external parasites or worms with a stage in the tissues) or allergic skin disease. On a three-group form this cannot be told apart from a neutrophil rise; only a smear or a full differential shows it.
- Artefact — on impedance counters platelet clumps can be counted as white cells, especially in cats, which inflates the white cell count and the lines on the form.
Lower than reference
A low GRA usually means fewer neutrophils. The most common cause is severe inflammation, when neutrophils move from the blood into the tissues faster than the marrow replaces them. Others include viral infections — canine parvovirus, FeLV and FIV in cats — and some drugs, including chemotherapy. A low GRA from an in-clinic analyzer is a reason for the vet to confirm the neutrophil count on a smear before drawing conclusions.
Look at together with
- Total white cell count (WBC) — GRA is part of it, and the percentage turns into an absolute number only through it.
- Neutrophils — if the lab also made a full differential, that number is the more precise one.
- MID and lymphocytes (LYM) — the other two groups; together with GRA their percentages add up to 100.
- Eosinophils — granulocytes by name, but visible as a separate number only in a five-type differential.
- Blood smear review — tells which cells are actually behind the number.
Units and conversion
The absolute count (GRA, GRAN) is reported as ×10⁹/L (×10^9/л on Russian-language forms). Forms also print it as 10³/µL, K/µL or thousand/µL — the same number, the factor is 1. The percentage (GRA%, GRAN%) is the share of granulocytes among all white cells. Absolute count = percentage × WBC ÷ 100. A vet relies on the absolute count: with a high WBC a “normal” percentage can hide a real rise, and with a low WBC a high percentage may mean an ordinary number of cells. 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: a GRA range from one machine is not interchangeable with a neutrophil range from a reference laboratory. The Merck Veterinary Manual warns that automated differential counts perform poorly on animal blood and should not be accepted without checking a blood film. So a GRA outside the range is first a reason to look at the smear, and a trend measured on the same analyzer says more than a single value.
Cats and dogs
In cats excitement alone can raise neutrophils noticeably, so a high GRA in a frightened cat may reflect the visit rather than disease. Cats are also the species in which platelet clumps most often push up white cell counts on impedance counters. FeLV and FIV are among the causes of a low neutrophil count in cats.
In a sick dog a stress pattern is expected: more neutrophils, fewer lymphocytes and eosinophils. On a three-group form it looks like a higher GRA together with a lower LYM. Parvovirus can make neutrophils, and with them GRA, drop sharply.
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.