FrançaisWhat cat blood work usually includes
The 2021 AAFP Feline Senior Care Guidelines recommend tailoring tests to each cat and increasing their frequency with age; they include blood pressure in the minimum assessment of both healthy and ill senior cats [1].
| Test | What it looks at | Examples of lines |
|---|---|---|
| CBC (complete blood count) | Red cells, white cells and platelets. | HCT, HGB, WBC, NEUT, LYMPH, PLT |
| Chemistry panel | Kidneys, liver, sugar, proteins and minerals. | CREA, BUN, SDMA, ALT, ALP, GLU, TP |
| Total T4 | Thyroid hormone, often checked in senior cats. | T4 |
| Urinalysis | Urine concentration, protein, sugar and sediment. | USG, UPC |
| Blood pressure | Not a blood test, but part of the senior check-up [1]. | Systolic pressure |
How to read a line of your cat’s results
Every line follows the same structure. Here is an example from the chemistry panel.
- Abbreviation CREA is creatinine, a kidney value. See our article on creatinine and BUN in cats.
- Result The result for this sample. Hydration at the time of sampling matters for kidney values [2].
- Unit mg/dL in the United States; µmol/L in Europe (× 88.4) [3].
- Laboratory interval The example uses the cat interval of the Merck Veterinary Manual [4]. Cat intervals differ from dog intervals.
- Flag H: above the interval. Your vet reads it with SDMA, BUN, the urinalysis and previous results.
Example cat values
| Line | Example cat interval [4] | Note |
|---|---|---|
| HCT / PCV | 30–45% | Lower than in dogs. |
| WBC | 5.5–19.5 × 10³/µL | Can rise briefly with excitement [5]. |
| PLT (platelets) | 300–800 × 10³/µL | Often falsely low because cat platelets clump easily [6]. |
| CREA (creatinine) | 0.9–2.2 mg/dL (80–194 µmol/L) | Depends on muscle mass [3]. |
| BUN (urea nitrogen) | 19–34 mg/dL | Also changes with meals and hydration. |
| ALT | 25–97 U/L | Can be falsely raised by haemolysis in cats [7]. |
| ALP | 0–45 U/L | Small increases matter more in cats than in dogs [8]. |
Cat-specific effects that can change a result
- Excitement and fear. Adrenaline released during handling can raise blood sugar, neutrophils and lymphocytes for a short time. Cats of any age show this “physiologic” pattern more often than other species [5]. See blood sugar in cats.
- Platelet clumps. Cat platelets are notoriously reactive and clump readily during sampling, which can produce a falsely low count. The count should be checked on a blood smear [6].
- Haemolysis. Red cells broken during sampling can raise measured ALT in cats, unlike in dogs [7].
- ALP behaves differently. In cats, ALP is specific to liver and bile problems but less sensitive, with a very short half-life, so even small increases deserve attention. An overactive thyroid can also raise it [8, 7].
- The thyroid. Hyperthyroid cats often have mild increases in ALT, AST and ALP [7], and the condition can also affect kidney values such as SDMA [2].
How to prepare your cat for blood work
- Follow your vet’s instructions about food. A recent meal can make the sample cloudy with fat (lipaemia), which can interfere with some measurements [9], and IRIS stages kidney disease on fasting creatinine [2].
- Ask whether water should stay available: hydration influences kidney values [2].
- Ask whether to give the usual medicines on the morning of the test, and bring a list of everything your cat receives.
- Use a carrier your cat knows, and bring previous results so trends can be compared.
For the French version of this guide, see Prise de sang du chat. Two cat-specific pitfalls have their own articles: low platelets in cats and high liver enzymes in cats.
Where to go next
Questions to ask your veterinarian
- Which values are outside the interval, and do they point in the same direction?
- Could stress during the visit explain the glucose or white cell results?
- Was the platelet count checked on a smear?
- Do the kidney values need a urinalysis or a blood pressure check to be interpreted?
- When should my cat’s blood work be repeated, given its age?
Get your cat’s whole report explained, value by value.
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Frequently asked questions
How is a blood test done on a cat?
A small amount of blood is taken from a vein, usually in the neck or a leg, and divided into tubes for the blood count and the chemistry panel. Many clinics use cat-friendly handling to keep the cat calm, which also limits stress effects on the results [5].
How long does cat blood work take?
In-clinic analysers can give a blood count and chemistry panel within the visit. Tests sent to an external laboratory, such as some thyroid or specialised tests, usually take one or more days.
How long should a cat fast before blood work?
Follow your vet’s instructions. Fasting reduces fat in the sample, which can interfere with some tests [9], and kidney staging uses fasting creatinine [2]. Ask whether water should stay available.
What does it mean if my cat has high ALT and ALP?
Both enzymes relate to the liver and bile flow. In cats, an overactive thyroid is a common reason for mild increases, and ALP increases deserve attention even when small [7, 8]. Your vet decides which tests come next.
Can a blood test detect cancer in a cat?
Blood work can show changes that raise suspicion, but it cannot confirm or rule out most cancers on its own. Imaging or sampling of the organ concerned is usually needed.
Sources
- Ray M et al. 2021 AAFP Feline Senior Care Guidelines. J Feline Med Surg. 2021;23(7):613-638. doi.org/10.1177/1098612X211021538
- International Renal Interest Society (IRIS). IRIS Staging System. iris-kidney.com/iris-staging-system
- eClinPath, Cornell University College of Veterinary Medicine. Creatinine. eclinpath.com/chemistry/kidney/creatinine
- Merck Veterinary Manual. Hematology and serum biochemical analysis reference ranges. merckvetmanual.com/reference-values-and-conversion-tables/reference-guides/serum-biochemical-analysis-reference-ranges
- eClinPath, Cornell University College of Veterinary Medicine. Leukogram patterns (physiologic leukocytosis). eclinpath.com/hematology/leukogram-changes/leukogram-patterns
- eClinPath, Cornell University College of Veterinary Medicine. Platelet number. eclinpath.com/hemostasis/tests/platelet-number
- eClinPath, Cornell University College of Veterinary Medicine. Alanine aminotransferase (ALT). eclinpath.com/chemistry/liver/liver-injury/alanine-aminotransferase
- eClinPath, Cornell University College of Veterinary Medicine. Alkaline phosphatase (ALP). eclinpath.com/chemistry/liver/cholestasis/alkaline-phosphatase
- eClinPath, Cornell University College of Veterinary Medicine. Interference indices (lipemia, hemolysis, icterus). eclinpath.com/chemistry/interference-indices
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.