By The Pawline veterinary teamVeterinary-reviewed by Alastair Greenway, BVM&S MRCVS · 25 July 2026
Reference range · mmol/L
109122
Reference
109–122
Direction
Both unusually high and low values carry meaning.
This is the conventional reference interval. Your pet’s own report may print a slightly different range — always read the value against that. Sign in to see your pet’s value on this strip.
Chloride moves largely in step with sodium and helps describe the body's acid-base balance, so it's interpreted alongside the other electrolytes rather than alone. Its main independent value is in acid-base assessment, where a chloride out of step with sodium is the informative finding.
Chloride is the main negatively-charged electrolyte in the fluid outside cells, and it usually travels as a shadow of sodium — where sodium goes, chloride tends to follow, to keep the blood electrically balanced. For that reason, much of the time chloride simply mirrors sodium and adds little on its own. Its distinctive value emerges in acid-base balance, where chloride can move independently of sodium, and that mismatch becomes the useful clue.
Chloride largely shadows sodium; its independent value is in acid-base balance, where a chloride out of step with sodium is the informative finding.
Reading chloride with sodium
The practical rule is to compare chloride against sodium:
Chloride moving with sodium usually just reflects water balance — the same story sodium is telling, adding little new.
Chloride moving out of step with sodium points to an acid-base disturbance. A chloride that is proportionally high (relative to sodium) can accompany certain metabolic acidoses; a chloride proportionally low can accompany metabolic alkalosis — classically from loss of stomach acid through vomiting, where chloride-rich fluid is lost.
This is why vets sometimes look at a "corrected chloride" (chloride adjusted for the sodium level) — it strips out the water-balance effect to reveal the true acid-base signal.
Reading a high or low result
A high chloride (relative to sodium) is read as part of an acid-base picture (some metabolic acidoses, certain fluid situations). A low chloride (relative to sodium) classically points to loss of stomach acid from vomiting, or metabolic alkalosis. In both cases, chloride is interpreted in the light of sodium and the acid-base status (bicarbonate/total CO2, and where measured, blood gases), rather than as an isolated number.
In chronic disease
Chloride is followed as part of the electrolyte and acid-base assessment in conditions involving vomiting, kidney disease, and fluid or acid-base disturbances. Its trend relative to sodium helps track acid-base balance over time and guides fluid therapy. On its own it rarely drives a decision, but as part of the electrolyte pattern it adds a distinct acid-base dimension.
Cat vs dog
Chloride is interpreted the same way in both species, with species-specific reference ranges that run a little higher in cats. The shadow-of-sodium behaviour and the acid-base logic apply to both. In each, the informative reading is chloride's relationship to sodium, not its absolute value alone.
How it's measured
Chloride is measured on a routine chemistry or electrolyte panel, in mmol/L (or mEq/L). It is read alongside sodium, potassium and bicarbonate/total CO2 as part of the electrolyte and acid-base picture; a corrected chloride may be calculated to isolate the acid-base component. Read the value against your own report's range.
What to do next
Chloride is best interpreted in relation to sodium and the acid-base status with your vet. A chloride that tracks sodium adds little; a chloride out of step with sodium points to an acid-base disturbance — for instance, a low chloride from persistent vomiting — worth understanding and correcting. As one of the electrolytes, it is read as part of the pattern rather than on its own.
Reference ranges reflect conventional laboratory intervals. Always interpret against your own lab's printed range and your veterinary surgeon's judgement. A brighter optimal band is shown only where a published guideline defines one, and it is cited.
This page is educational and is not a diagnosis. Lab results are interpreted in the full clinical context by your veterinary surgeon; a single value rarely tells the whole story.
