Blood tests in cats

Blood tests have a wide range of uses and are a common type of medical test.

Blood tests can help diagnose conditions or assess the health of certain organs.

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What it’s for

Why do cats need blood tests?

A blood test can be used to:

  • Assess your cat’s general health: especially important for older cats or those undergoing anaesthesia.
  • Find out how well certain organs are working, for example, the liver and kidneys.
  • Check if your cat has an infection.
  • Help diagnose certain diseases.


What do tests measure?

Vets use a variety of blood tests to check different aspects of your cat’s health:

  • Routine tests: an overview of an animal’s health for both healthy pets and sick pets. The two routine tests most commonly used are:
    • Complete blood count
    • Biochemistry profile
  • Special tests: are done to investigate or monitor a specific problem, such as:
    • T4 test: to help identify thyroid disease
    • Glucose or fructosamine test: sugar diabetes (diabetes mellitus)
    • SDMA test: kidney disease 
    • FIV and FeLV tests: viral diseases
    • fPL test: pancreatitis 
    • Bile acid stimulation test: liver disease


Complete blood count or haematology

This is a test to check the types and numbers of cells in your cat’s blood, including red blood cells, white blood cells and platelets.

This can help give an indication of your cat’s general health, as well as provide important clues about health problems they may have. For example:

  • Dehydration
  • Anaemia
  • Infection or inflammation
  • Bleeding or clotting disorders
  • Some types of cancer


Biochemistry profile

Measures a variety of chemicals and enzymes in your cat’s blood to provide general information about organ health and function.

The range of parameters can include: electrolytes, blood sugar levels, chemical substances and enzymes.

This type of blood test is usually the first step in investigations and helps us choose more specific tests later.


General health assessment
  • A general health blood test is especially important for older cats or those undergoing anaesthesia.
  • A basic biochemistry profile gives vets a small window that can highlight a problem elsewhere.
  • This can reflect a change in organs such as liver, kidneys, pancreas, hormonal organs (endocrine system) and others.


Liver assessment
  • When the liver is damaged, it releases substances into the blood and levels of proteins produced by the liver begin to drop.
  • Changes can be seen in the levels of: albumin, ALP (alkaline phosphatase), ALT (alanine aminotransferase), ammonia, AST (aspartate aminotransferase), bilirubin, BUN (Blood urea nitrogen), cholesterol, globulin, total protein.
  • To obtain a more detailed picture of liver function, bile acids stimulation test is usually added.


Kidney assessment
  • In the same way as the liver, these substances can increase or drop due to a problem in the urinary system.
  • In addition to blood assessment, it is important to examine your cat’s urine to obtain a more complete picture of kidney function.
  • The main substances we look for in the blood are: BUN, creatinine, total protein, albumin and electrolytes (sodium, potassium, chloride, phosphate).
  • Some cases require SDMA testing to monitor a problem on the kidney filtration rate.


The purpose of this article is only to provide a short list of the most important parameters of some organs.

There is a wide range of parameters that can be included in a biochemistry profile test, from the most basic to the most comprehensive.

Interpreting biochemistry blood results is quite complex since a combination or different values refer to different organs and different diseases on that same organ.

Many cases may still require further investigation with x-rays, scans, CT or MRI to help diagnose a problem.

How it’s done

How are blood tests performed?

  • Vets take a small blood sample to run the necessary tests.
  • Blood is drawn from blood vessels in your cat’s neck or leg.
  • First, the area is shaved and then cleaned to kill bacteria on the skin.
  • The test isn’t painful, but the handling and positioning may cause some level of distress in animals who are very fearful.
  • Vets and nurses will find a way that suits your cat to keep them as relaxed and calm as possible.
  • Samples are analysed at the vet practice or sent to a special laboratory for testing.
  • Your vets will discuss the results with you and you can request the results for yourself.

How to prepare your cat for a blood test?

  • Don’t feed your cat for 6-12 hours before a planned blood test.
  • Always confirm with your vet whether your cat needs to have an empty tummy and if you need to change any medication routine.
  • Keep water available at all times.
  • Avoid contact with dogs or loud noises. If necessary leave your cat in the car or reception may take him and leave him in a quiet place waiting for his turn.
  • Minimise stress, your vet can prescribe an anti-anxiety medication such as gabapentin for very fearful cats.
  • Your vet may apply a local anaesthetic cream to the sampling site before the test if your cat has very sensitive skin.


How much it costs to do a blood test?

  • Cost depends on the type and number of tests that are needed.
  • If the blood is run through the vet practice or sent to a special laboratory for testing.
  • If your cat suffers from a long-term condition, they may need regular blood tests for monitoring purposes and treatment adjustments.

It’s important to discuss costs with your vet before agreeing to go ahead with blood tests and if your cat has a long-term condition, ongoing blood tests need to be taken into account.


Are there any risks associated with taking bloods?

The risk of taking blood from your cat

is minimal, and the information your vet gains from the testing can be vital.

Potential risks are:

  • Bruising on the collection site: due to a little blood leaking under the skin.
  • Haematoma: a larger pool of blood under the skin after sampling forming a swelling. Cats with clotting problems are most susceptible to this.
  • Skin irritation or clipper rash: if your cat has sensitive skin, the clippers and the alcohol swabs can sometimes cause mild irritation of the area where the blood is taken from.
  • Inflammation of the vein (phlebitis): rare condition.
  • Skin Infection at the site of the test: vets clean the skin with alcohol to reduce this risk.

Recovery tips

How to help your cat recover after a blood test?

  • Bruises usually fade within a few days. Your vet may apply or suggest arnica cream.
  • Keep the experience positive and try not to let your cat associate it with a negative outcome.
  • Your vets usually try to make it as stress free as possible.
  • You can also have an impact by providing positive reinforcement after the bloods being taken such as giving treats.
  • Some cats find procedures like blood tests or any trips to the vet stressful. Talk to your vet team about arranging time to create positive experiences with the staff.
  • If your cat is very anxious but has to have regular blood tests, talk to your vet about how you can help prepare your cat for the trip to the vets and during the blood sampling.

When to worry

When to worry about your cat after a blood test

Rarely, blood taking can cause vein inflammation (phlebitis).

The main symptom of phlebitis is inflammation of the sampled blood vessel and surrounding area, causing:

  • Warmth
  • Swelling
  • Redness
  • Pain
  • Hardened blood vessel

Contact your vets if you see any of these signs.

Joii can help with:

  • Advice on haematomas, bruises or clipper rash.
  • Identifying signs of blood vessel inflammation.
  • Advice on how to help your cat cope with repeated vet visits and blood tests.


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