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Chloride (Cl)

Electrolytes & minerals ·Also called: Cl, chloride, serum chloride

What it is

Chloride is the main negatively charged particle in the fluid outside cells. It is handled by the kidneys and lost in stomach acid, sweat-free though dogs and cats are, and its level usually parallels sodium closely.

Why your vet measures it

Chloride is chiefly used to interpret acid-base disturbances. A chloride that has fallen much further than sodium points towards loss of stomach acid — persistent vomiting, or an obstruction high in the digestive tract.

What a high result can mean

  • Dehydration, in step with a raised sodium
  • Certain kidney disorders affecting acid handling
  • Over-administration of saline fluids

What a low result can mean

  • Persistent vomiting, particularly of stomach contents
  • An obstruction at the stomach outflow or upper small intestine
  • Diuretic treatment
  • Alongside a low sodium in Addison's disease or fluid loss

Questions worth asking your vet

  • Has the chloride fallen more than the sodium, and does that point anywhere?
  • Could persistent vomiting explain this pattern?

Related terms

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