Urine colour and clarity in cats and dogs

What it shows

This article covers two lines of the form. The main one is colour; the second is clarity (turbidity).

• Colour is judged by eye and written in words — for example yellow, red or brown — often with a depth word such as “light” or “dark”. Usual urine is light to medium yellow, pale yellow to amber, and transparent. Colour depends on how concentrated the urine is, which is why it is read together with specific gravity. The judgement is subjective and differs between observers.
• Clarity describes how much material is floating in the urine: clear, slightly cloudy, cloudy, opaque or flocculent (with visible flakes). Fresh urine is usually clear to very slightly cloudy.

Higher than reference — what it may be a sign of

Possible reasons for an unusual colour or cloudiness:

• Colourless or very pale — dilute urine; it can go with drinking and urinating a lot, which the vet may look into.
• Dark yellow — concentrated urine; very dark yellow — concentrated urine or bilirubin in urine.
• Greenish tint — bilirubin.
• Red to brownish-red — blood (intact red cells), free haemoglobin or myoglobin (a muscle pigment).
• Reddish-brown to brown — myoglobin or altered haemoglobin.
• Unusual colour from medicines — some medicines and other substances change urine colour; the vet compares this with what the animal receives.
• Cloudy urine — more red or white blood cells, many crystals, bacteria, fat, mucus, semen or contamination with faeces. Microscopy of the sediment usually finds the cause; depending on the cause, urine may become clear after centrifugation.

Lower than reference

There is no “lower” for these lines. What matters is the opposite: a usual colour and clear urine do not exclude disease — significant illness can be present with urine that looks normal.

Look at together with

• Urine specific gravity — colour largely reflects concentration, so the two are read side by side.
• Blood in urine and red and white cells in the sediment — show whether red urine comes from intact red cells or from pigment, and whether cloudiness comes from cells.
• Bilirubin in urine — for very dark yellow or greenish urine.
• Crystals and bacteria — frequent causes of cloudy urine.

Units and conversion

These lines have no unit and nothing to convert. Colour is written in words — straw, yellow, amber, red, brown and so on, sometimes with “light” or “dark”. Clarity is written as clear, slightly cloudy, cloudy, opaque or flocculent; some forms use “transparent / turbid”. Because the scale is a matter of eye, comparing results from the same lab is more reliable than comparing different labs.

Reference range

The reference range is on your lab’s form; it is usually given in words, such as “yellow, clear”. How the sample was handled matters: urine is best examined within 30 minutes; if that is not possible it can be refrigerated for up to 24 hours. Chilling does not change pH or specific gravity but can make crystals settle out, so a refrigerated sample may look cloudier than it was in the bladder. The sample is warmed to room temperature and mixed well before it is graded.

Cats and dogs

Sources

1. eClinPath (Cornell University) — Urinalysis: visual features
2. eClinPath (Cornell University) — Urinalysis: overview
3. Whitbread TJ. Urinalysis. Merck Veterinary Manual
4. VCA Animal Hospitals — Urinalysis