Neutrophils in cats and dogs
Neutrophils are the most numerous white blood cells in healthy cats and dogs and the first line of defence against bacteria. A blood count shows them as an absolute number and as a percentage, sometimes split into mature segmented cells and young band cells. A vet reads the absolute number and the share of young forms: together they tell inflammation from stress or excitement.
What it shows
Neutrophils are made in the bone marrow and leave the blood for tissues where they are needed — to infection or inflammation. Part of them circulate freely, and part line the walls of blood vessels (the marginating pool); a blood sample counts only the circulating part. That is why the count can change within minutes without any new cells being made: adrenaline and stress hormones move neutrophils from the vessel walls into the stream.
Mature neutrophils have a nucleus divided into segments — segmented neutrophils. Young ones have a horseshoe-shaped nucleus — band neutrophils. When the body needs many cells quickly, the marrow releases bands and even younger forms; more young forms in the blood is called a left shift. The more severe the left shift, the stronger the inflammatory stimulus.
Higher than reference — what it may be a sign of
- Inflammation — infectious or not, often with a left shift. In dogs it can reach the highest values, for example with pus in a closed cavity such as pyometra.
- Stress and corticosteroids (the body’s own cortisol or steroid medicines): mature neutrophils go up without a left shift, usually with fewer lymphocytes and eosinophils.
- Excitement (adrenaline) — a physiological rise without a left shift, most often in cats of any age, often with more lymphocytes as well. It fades within about 30 minutes after the animal calms down.
- Immune-mediated hemolytic anemia and, rarely, blood cancers or a parasite such as Hepatozoon canis when the rise is extreme.
Lower than reference
Neutropenia — too few neutrophils — matters more than most other low counts on the leukogram.
- Overwhelming use in tissues — a common cause: severe inflammation or sepsis, usually with a degenerative left shift (more young cells than mature ones) and toxic change.
- Destruction: parvovirus in dogs, panleukopenia in cats, immune-mediated disease.
- Too little production: marrow disease, Ehrlichia canis, some drugs; in cats FeLV and FIV.
- Breed: some healthy Belgian Tervurens, Australian Shepherds and Labradors have lower counts.
Look at together with
- Total white cell count (WBC) — neutrophils are its largest part, so a change in WBC is usually a change in neutrophils.
- Lymphocytes, monocytes and eosinophils — the pattern of all cells tells inflammation from a stress or excitement response.
- Blood smear review — the vet or laboratory looks for toxic change: features of neutrophils released in a hurry during strong inflammation.
Units and conversion
The absolute count is reported as ×10⁹/L (×10^9/л), as 10³/µL, K/µL or thousand/µL (тыс/мкл) — these are the same number, so 8.5 ×10⁹/L is 8.5 K/µL. Segmented and band neutrophils are given as absolute numbers in ×10⁹/L too.
The percentage (NEU%) is the share of neutrophils among all white cells. Absolute count = percentage × total WBC ÷ 100. A vet relies on the absolute count: if the total WBC is high or low, the same percentage means a very different 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 differs between species and analyzers. Many forms flag both the absolute count and the percentage; it is the absolute count that tells whether neutrophils are really increased or decreased. A single result taken at a stressful visit may look different from one taken at home calm, which is why a series of tests says more than one result.
Cats and dogs
Cats have a large pool of neutrophils on the vessel walls, so excitement or stress can raise the count two to three times — more than in dogs. A frightened cat at the clinic may show more neutrophils and lymphocytes without any disease. In a cat with unexplained neutropenia, eClinPath advises testing for FeLV and FIV.
In dogs inflammation can raise neutrophils highest of the domestic species, and in a sick dog a stress pattern (more neutrophils, fewer lymphocytes and eosinophils) is expected. Parvovirus can cause a sharp drop. Breed matters as well: some healthy Belgian Tervurens, Australian Shepherds and Labradors have lower counts, and grey Collies can have cyclic neutropenia.
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.