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BLOOD COUNT · CATS

Anemia in cats: what a low PCV or hematocrit means on your cat’s blood work

Cats normally have fewer red cells than dogs, and they hide illness well, so anemia is often found on blood work before it is noticed at home. Here is how to read the red cell lines, judge severity and understand the bone marrow’s response.

Written by the AI DiagAnimals editorial teamReviewed by the AI DiagAnimals TeamUpdated Our editorial policy

The essentials

A cat is anemic when its hematocrit (HCT), PCV or hemoglobin is below the laboratory’s cat interval, which is lower than a dog’s. Vets grade the severity, then count aggregate reticulocytes to see whether the bone marrow is responding. A response points to blood loss or red cell destruction; no response points to reduced production, often from another illness.

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What anemia means for a cat

Anemia is a decreased hematocrit or hemoglobin [1]. Cats have lower normal values than dogs: the Merck Veterinary Manual lists a PCV of 30–45% for cats, against 35–57% for dogs [2]. Comparing a cat with a dog interval, or with human values, gives the wrong answer.

As in dogs, sedation can temporarily lower the hematocrit by storing red cells in the spleen, and kittens under about 4 months have a physiologic anemia while they grow [1].

How to read the PCV or hematocrit line

Here is an example line from a cat’s blood count.

An annotated line from a lab report · Illustrative example
AbbreviationResultUnitLaboratory intervalFlag
PCV Packed cell volume21%30–45L
  1. Abbreviation PCV, or HCT when calculated by the analyser: the share of the blood made of red cells [1].
  2. Result 21% in this illustrative line.
  3. Unit %; some laboratories write L/L (0.21 L/L = 21%).
  4. Laboratory interval The example uses the cat interval of the Merck Veterinary Manual [2].
  5. Flag L: below the interval. Cornell’s guidelines would call 15–25% a moderate anemia in a cat [1].

How severe is it?

Guidelines used by the Cornell clinical pathology laboratory, described by the authors as arbitrary and subjective [1]. Cats with a slowly developing anemia can show surprisingly few signs.
Grade (cats)Hematocrit
Reference interval at Cornell31–48%
Mild25–30%
Moderate15–25%
SevereBelow 15%

Is the bone marrow responding? Aggregate reticulocytes

Cats release two kinds of young red cells. Only the “aggregate” reticulocytes are counted to judge the current response; the “punctate” form can persist for up to three weeks and reflects past activity [3].

The marrow needs 3 to 5 days to respond, so a sudden anemia can look non-regenerative at first [1].

Approximate Cornell guidelines, read in light of the severity of the anemia.
Aggregate reticulocytes (cats)Degree of regeneration [4]
Below about 61,000/µLInadequate or no regeneration
About 61,000–85,000/µLEquivocal
About 86,000–100,000/µLMild
Above about 100,000/µLModerate to marked

The main families of causes in cats

  • Reduced production. Inflammation and chronic disease commonly cause a mild to moderate non-regenerative anemia. Feline leukaemia virus (FeLV) can affect red cell production [1, 5].
  • Red cell destruction. Blood parasites such as haemotropic Mycoplasma, immune-mediated hemolytic anemia (less common in cats than dogs), and toxins: paracetamol (acetaminophen) is particularly dangerous for cats [5, 6].
  • Blood loss. Injury, bleeding disorders, or heavy flea or parasite burdens, especially in kittens [5].

The values often read with anemia

Platelets

Cat platelets clump easily, which can make the count falsely low; the smear confirms it.

Read the article

Kidney values

Creatinine, BUN and SDMA give context, as chronic illness often lowers red cell production.

Read the article

Bilirubin

Can rise when red cells are destroyed.

See how a cat’s blood count is explained in Luna’s sample report. En français : anémie du chat.

Anemia is common in cats with feline leukemia virus: see FeLV and FIV in cats.

Questions to ask your veterinarian

  1. How severe is my cat’s anemia, and has it changed since the last test?
  2. What is the aggregate reticulocyte count: is the marrow responding?
  3. Should we test for FeLV, blood parasites or other causes?
  4. Do the kidney values or other results suggest a chronic illness behind it?
  5. Which signs at home should make me call you straight away?
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Frequently asked questions

What is a normal PCV for a cat?

It depends on the laboratory: for example 30–45% in the Merck Veterinary Manual and 31–48% at Cornell. Cats normally run lower than dogs [1, 2].

Can worms or fleas cause anemia in cats?

Yes. Heavy flea burdens and blood-sucking parasites can cause blood-loss anemia, especially in kittens [5].

Can a cat recover from anemia?

Many do, once the cause is found and treated. The outlook depends on the cause and severity, which your vet assesses.

Is a cat with anemia in pain?

Anemia itself is not usually painful, but the underlying illness can be. Weakness, hiding and loss of appetite are reasons to contact your vet.

What are the different types of anemia?

Vets classify anemia by severity, by red cell size and colour (MCV, MCHC) and above all by whether the marrow is responding: regenerative or non-regenerative [1].

Sources

  1. eClinPath, Cornell University College of Veterinary Medicine. Anemia: overview. eclinpath.com/hematology/anemia
  2. Merck Veterinary Manual. Hematology (complete blood count) reference ranges. merckvetmanual.com/reference-values-and-conversion-tables/reference-guides/hematology-reference-ranges
  3. eClinPath, Cornell University College of Veterinary Medicine. Assessment of regeneration. eclinpath.com/hematology/anemia/assessment-regeneration
  4. eClinPath, Cornell University College of Veterinary Medicine. Absolute reticulocyte count. eclinpath.com/hematology/tests/absolute-reticulocyte-count
  5. eClinPath, Cornell University College of Veterinary Medicine. Anemia summary: mechanisms and causes. eclinpath.com/hematology/anemia/cause-of-anemia-summary
  6. Garden OA et al. ACVIM consensus statement on the diagnosis of immune-mediated hemolytic anemia in dogs and cats. J Vet Intern Med. 2019;33(2):313-334. doi.org/10.1111/jvim.15441

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.

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