# Units of Measure in Veterinary Medicine: mg, mcg, mL, mEq, mOsm, IU, U, ppm — and Which to Avoid

> Unit abbreviations used in veterinary medicine — mass, volume, concentration, energy and time (mg, mcg, mL, dL, fL, mEq, mOsm, IU, ppm, kcal, h, d) — with the unit forms ISMP says to avoid (µg, cc, U, IU, trailing zeros).

- Source page: https://wevet.in/vet-abbreviations/units-of-measure-abbreviations/
- Type: Abbreviations
- Publisher: WeVet
- Updated: 2026-11-01
- Audience: veterinarians and veterinary students

Unit abbreviations listed by the Merck Veterinary Manual [1], with the unit and dose designations that the Institute for Safe Medication Practices lists as error-prone and its recommended alternatives [2].

## Units of measure

| Abbreviation | Meaning | Caution |
|---|---|---|
| g | Gram [1] |  |
| kg | Kilogram [1] |  |
| mg | Milligram [1] |  |
| mcg | Microgram [1] | ISMP recommends "mcg" instead of µg, which is mistaken as mg [2]. |
| pg | Picogram [1] |  |
| lb | Pound [1] |  |
| oz | Ounce [1] |  |
| L | Litre [1] |  |
| dL | Decilitre [1] |  |
| mL | Millilitre [1] | ISMP recommends "mL" instead of cc (cubic centimetres), which is mistaken as u (units) [2]. |
| fL | Femtolitre [1] |  |
| gal | Gallon [1] |  |
| tbsp | Tablespoon [1] |  |
| tsp | Teaspoon [1] |  |
| m | Metre [1] |  |
| cm | Centimetre [1] |  |
| mm | Millimetre [1] |  |
| nm | Nanometre [1] |  |
| in | Inch [1] |  |
| ft | Foot [1] |  |
| mol | Mole [1] |  |
| M | Molar (moles per litre) [1] |  |
| mEq | Milliequivalent [1] |  |
| mOsm | Milliosmole [1] |  |
| IU | International unit [1] | ISMP: IU is mistaken as IV or the number 10; write "unit(s)" [2]. |
| U | Unit [1] | ISMP: U or u is mistaken as zero or the number 4, or as cc; write "unit(s)" [2]. |
| ppm | Parts per million [1] |  |
| ppb | Parts per billion [1] |  |
| cal | calorie (small calorie; 1 kcal = 1000 cal) [1] |  |
| kcal | Kilocalorie [1] |  |
| Mcal | Megacalorie [1] |  |
| J | Joule [1] |  |
| s | Second [1] |  |
| min | Minute [1] |  |
| h | Hour [1] | ISMP recommends hr, h or hour instead of the symbol ° for hour [2]. |
| d | Day [1] |  |
| wk | Week [1] |  |
| mo | Month [1] |  |
| yr | Year [1] |  |
| bpm | Beats per minute [1] |  |

## Writing doses safely

- Do not use trailing zeros for whole-number doses: 1.0 mg is mistaken as 10 mg if the decimal point is not seen [2].
- Use a leading zero before a decimal point when the dose is less than one measurement unit: .5 mg is mistaken as 5 mg if the decimal point is not seen [2].

## Frequently asked questions

### Should I write mcg or µg?

ISMP recommends mcg, because µg is mistaken as mg [2].

### Why should "cc" not be used?

ISMP reports that cc is mistaken as u (units) and recommends mL [2].

## References

[1] Abbreviations — Merck Veterinary Manual. https://www.merckvetmanual.com/resourcespages/abbreviations
[2] ISMP List of Error-Prone Abbreviations, Symbols, and Dose Designations — Institute for Safe Medication Practices (ISMP) (2024). https://online.ecri.org/hubfs/ISMP/Resources/ISMP_ErrorProneAbbreviation_List.pdf

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Numbers in [brackets] cite the references above. For veterinary professionals. Information supports — never replaces — clinical judgement; always check the current product label and local regulations.
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