Taurine in cats and dogs

What it shows

Taurine is not built into proteins; it works inside cells, most of all in the heart muscle and the retina. When there is too little of it for a long time, the heart muscle weakens and the heart chambers stretch — this is called dilated cardiomyopathy (DCM). In cats, a lack of taurine also damages the centre of the retina.

The lab can measure taurine in two materials. Plasma (the liquid part of the blood) reflects what is circulating right now; the full amino-acid profile is also done on plasma. Whole blood includes the cells as well, and white blood cells in particular hold a lot of taurine. The two numbers are not interchangeable: each has its own reference interval. For Golden Retrievers and other taurine-sensitive breeds, the cardiology lab whose guidance is cited here asks for paired samples whenever possible; if only one is possible, it prefers whole blood.

Higher than reference — what it may be a sign of

• Sample handling. White blood cells contain a lot of taurine. If the cell layer is disturbed while plasma is taken off, the plasma value can come out falsely high — one reason whole blood is preferred when only one test is done. The lab also asks that plasma not be hemolyzed.

Lower than reference

A low or borderline value is the reason the test exists. It supports taurine deficiency as a possible cause, or contributor, of heart muscle disease — but a number alone does not diagnose DCM: the heart itself is assessed by ultrasound. In cats a lack of taurine is linked to diets without enough animal protein, since plant proteins contain no taurine; it now occurs occasionally in cats fed vegetarian, baby-food or home-cooked diets. In dogs, the diet’s composition is discussed as a factor as well. What to do with a low result — and whether to change anything — is decided by the vet.

Look at together with

• Heart ultrasound (echocardiography) — shows whether the heart is actually enlarged and weak; taurine only helps to explain why.
• NT-proBNP and troponin — blood markers of heart strain and heart muscle damage.
• Paired plasma and whole-blood results — when both are on the form, they are read together rather than one by one.
• Taurine already being given — if the vet has already prescribed taurine, a repeat test shows whether levels have come up.
• A repeat test after a few months — the trend after a change tells more than a single value.

Units and conversion

Taurine is reported in µmol/L or nmol/mL. These are the same unit, written two ways: 250 nmol/mL is 250 µmol/L, so nothing needs converting. In the app plasma and whole-blood taurine are kept as two separate rows, because their numbers sit at different levels and cannot be put on one line.

Reference range

The reference range is on your lab’s form, and it is separate for plasma and for whole blood. For Golden Retrievers and other taurine-sensitive breeds, the UC Davis cardiac genetics lab uses these bands: whole blood above 250 nmol/mL is normal, 200–250 marginal, below 200 low; plasma above 70 nmol/mL is normal, 60–70 marginal, below 60 low. These are one lab’s working bands for dogs, not reference ranges for cats or for every lab.

Because a disturbed cell layer can raise plasma taurine, the result is read with how the sample was handled in mind. Samples that cannot reach the lab the same day are usually frozen.

Cats and dogs

Sources

1. UC Davis School of Veterinary Medicine. Amino Acid Laboratory — sample submission for plasma and whole-blood taurine.
2. Stern Cardiac Genetics Laboratory, UC Davis. Taurine testing recommendations for dogs (Golden Retrievers and other taurine-sensitive breeds).
3. Kittleson MD. Dilated Cardiomyopathy in Dogs and Cats. Merck Veterinary Manual, professional version, full review January 2023.
4. Sanderson SL. Nutritional Requirements of Small Animals. Merck Veterinary Manual, professional version, full review November 2023.
5. VCA Animal Hospitals. Taurine.