FrançaisWhat platelets do and how they are counted
Platelets are produced in the bone marrow and circulate for a few days. When a small vessel is injured, they stick to the wall and to each other to seal it, before the clotting proteins take over.
The count is part of the complete blood count (CBC). Analysers report it in several equivalent units: 200 × 10⁹/L, 200 G/L and 200 K/µL (× 10³/µL) all mean 200,000 platelets per microlitre. Normal dogs and cats usually have counts close to or above 200,000/µL [1].
Because machines can be fooled, the laboratory or your vet also looks at a blood smear under the microscope. Each platelet seen per field at high magnification corresponds to roughly 15,000/µL, which allows a quick estimate [1].
How to read the platelet line on the report
The platelet line is usually near the end of the blood count, after the red and white cells.
- Abbreviation PLT, sometimes followed by MPV (mean platelet volume), which describes their size.
- Result 62 K/µL means 62,000 platelets per microlitre of blood.
- Unit K/µL, × 10⁹/L and G/L give the same number. Check before comparing two reports.
- Laboratory interval The interval of this laboratory and analyser for dogs.
- Flag L: below the interval. The next step is to check the smear for clumps.
Look also for a laboratory comment such as “platelet clumps seen” or “count verified on smear”. It changes the meaning of the number completely.
Platelet clumps: the most common false low count
Platelets are designed to stick together. If the blood flows slowly or turbulently during collection, they can form clumps in the tube. The analyser then counts each clump as a single particle, or not at all, and the result is falsely low. This is called pseudothrombocytopenia [1, 4].
It is a frequent pre-analytical error [4], and it can lead to unnecessary tests and treatment if it is not recognised [5]. That is why a low count should always be checked on a blood smear before anything else [1, 3]. Warming the sample does not reliably prevent clumping in dogs [1, 4]; a new sample, sometimes in a different tube, is the usual solution [1].
Some dogs, such as many Cavalier King Charles Spaniels, have unusually large platelets that analysers may not count correctly [1].
Platelet levels and bleeding risk
| Platelet count | What is generally described |
|---|---|
| Within the laboratory interval (for example 211,000–621,000/µL in the Merck Veterinary Manual [7]) | Usual values for dogs; healthy dogs are generally close to or above 200,000/µL [1]. |
| Below the interval but above 50,000/µL | Mild to moderate decrease. Spontaneous bleeding is not expected from the count alone [1]. |
| Below about 50,000/µL | Bleeding can occur after trauma or surgery [1]. |
| Below about 30,000/µL | Spontaneous bleeding becomes possible, although some dogs with very low counts show few signs [1]. |
Why platelets can be low in a dog
Once clumping is excluded, a true thrombocytopenia comes from one or more of four mechanisms [1].
- Destruction. The immune system removes platelets. Immune thrombocytopenia (ITP) is the most common acquired platelet disorder in dogs [2].
- Consumption. Platelets are used up faster than they are replaced, for example during major bleeding or widespread clotting.
- Reduced production. The bone marrow makes too few, because of a disease or a medicine affecting it.
- Sequestration. Platelets are held in an enlarged spleen or another organ.
Immune thrombocytopenia can be primary, or triggered by another condition such as an infection, a tumour or a medicine. The 2024 ACVIM consensus describes it as a diagnosis of exclusion and lists which underlying diseases to screen for first [2]. In dogs receiving platelet transfusions in one referral centre, immune thrombocytopenia was the most frequent cause, and bleeding was mostly digestive or in the skin [6].
The values often read with platelets
See how a markedly low count is explained in Monty’s sample report, and the blood count abbreviations. For cats, whose platelets clump even more easily, see low platelets in cats.
Low platelets are the most common finding in ehrlichiosis and anaplasmosis: see tick-borne diseases in dogs.
When the immune system destroys platelets: ITP in dogs.
En français : plaquettes basses chez le chien.
Questions to ask your veterinarian
- Was the platelet count checked on a blood smear, and were clumps seen?
- Should we repeat the count on a new sample before going further?
- Is the count low enough to change what my dog can do this week, such as running, rough play or a planned procedure?
- Which underlying causes do you want to rule out, and which tests are needed?
- Which signs at home should make me call you straight away?
Get your dog’s whole blood count explained, line by line.
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Frequently asked questions
What is a dangerously low platelet count in a dog?
Spontaneous bleeding is generally not expected above about 30,000 platelets/µL, and bleeding after surgery or trauma becomes a concern below about 50,000/µL [1]. Any bleeding sign needs prompt veterinary attention, whatever the count.
Can a dog survive with low platelets?
Yes, many dogs do. The outlook depends on the cause, the count and the response to treatment, so ask your vet what applies to your dog. A falsely low count due to clumps needs no treatment at all [1, 5].
How do vets count platelets on a blood smear?
They count platelets in several microscope fields at high magnification: each platelet per field corresponds to roughly 15,000/µL. They also check the edges of the smear for clumps [1].
Can food increase my dog’s platelet count?
No food is known to correct a true thrombocytopenia. Treatment targets the cause. Avoid supplements or remedies that can affect clotting unless your vet agrees.
Sources
- eClinPath, Cornell University College of Veterinary Medicine. Platelet number. eclinpath.com/hemostasis/tests/platelet-number
- LeVine DN et al. ACVIM consensus statement on the diagnosis of immune thrombocytopenia in dogs and cats. J Vet Intern Med. 2024;38(4):1958-1981. doi.org/10.1111/jvim.16996
- Perez-Ecija A et al. Utility of immature platelet fraction in the Sysmex XN-1000V for the differential diagnosis of central and peripheral thrombocytopenia in dogs and cats. J Vet Intern Med. 2024;38(3):1512-1519. doi.org/10.1111/jvim.17074
- Williams TL, Archer J. Effect of prewarming EDTA blood samples to 37 °C on platelet count measured by Sysmex XT-2000iV in dogs, cats, and horses. Vet Clin Pathol. 2016;45(3):444-449. doi.org/10.1111/vcp.12378
- Vasilatis DM et al. Amikacin disaggregates platelet clumps in EDTA blood samples from cats and dogs when added postcollection. Vet Clin Pathol. 2023;52(2):228-235. doi.org/10.1111/vcp.13203
- Saint-Pierre LM et al. Retrospective evaluation of fresh platelet concentrate administration in dogs: patient characteristics, outcomes, and transfusion practices in 189 transfusion episodes (2008-2019). J Vet Emerg Crit Care. 2023;33(3):360-370. doi.org/10.1111/vec.13281
- Merck Veterinary Manual. Hematology reference ranges. merckvetmanual.com/reference-values-and-conversion-tables/reference-guides/hematology-reference-ranges
Laboratory methods and reference intervals vary. This article explains; it does not diagnose. For a decision about your pet, use the original report and talk to your veterinarian. Our editorial policy.