Dark yellow dog urine and what the colour is telling you

What urine colour mostly reflects

The colour of urine depends first of all on how concentrated it is. When the kidney holds water back, the urine passed is loaded with pigments, urochrome in particular, and the shade runs from deep yellow to amber. An animal that has just had a long drink or eats wet food passes almost colourless urine with nothing wrong behind it. The same dog can show two very different colours in one day: the morning urine, after a night without drinking, is the darkest.

Dark yellow urine is usually concentrated urine, the urine of an animal that has drunk little, that has been running in warm weather, that is vomiting or has diarrhoea. What counts is not one dark puddle but whether it carries on. Dark urine on a summer morning after a long walk does not weigh the same as dark urine for several days running in a dog that is drinking normally.

The opposite signal often goes unnoticed even though it deserves more attention. Urine that is always very pale, like water, in an animal that drinks a great deal and asks to go out at night, means the urine is no longer being concentrated. It is that picture, rather than dark urine, that most often leads a vet to ask for a urine specific gravity, a blood sample and a check for glucose.

Colours that concentration does not explain, and what the vet looks into

Some shades have nothing to do with how much the animal has drunk. None of them can be judged by eye, and each opens a different line of enquiry.

Red, pink or the colour of meat juices: this may be blood in the urine, or free haemoglobin when red cells are being broken down in the circulation. Both look the same, and they are separated in the laboratory on the urine sediment after spinning the sample, by looking for intact red cells. In an unspayed bitch, a vulval discharge can also colour the sample you collect.

Dark brown, the colour of tea or cola: this suggests myoglobin, the muscle pigment that passes into urine after muscle damage, or again haemoglobin.

Very dark yellow turning orange or brownish green, sometimes with yellow foam when the pot is shaken: this points towards bilirubin, and so towards the liver, the bile ducts and the breakdown of red cells. The species difference matters here. In dogs, a small amount of bilirubin in urine can occur without disease, particularly in concentrated urine and in males, whereas in cats any bilirubin in the urine is treated as abnormal and is followed up.

Bright, almost fluorescent yellow: very often a vitamin supplement, B group vitamins especially, whose excess is cleared in the urine. This is harmless and is the most likely explanation in an otherwise well animal.

Cloudy: crystals, cells, mucus, or simply a sample scooped off the ground. Cloudy urine is not necessarily infected, and clear urine does not rule an infection out.

What the smell does and does not tell you

A strong smell of ammonia nearly always means concentrated urine, or urine that has been standing: the urea in it breaks down to ammonia, which is why a carpet or a litter tray soaked for a few hours smells so sharp. A frankly foul smell together with frequent, small, painful attempts to pass urine points towards a urinary infection, but smell alone cannot establish it and only a urine test with culture can. A smell described as sweet or like apples is reported where there is glucose or ketones in the urine. An entire male cat has very pungent urine for hormonal reasons, with no illness involved.

Collecting a sample that is worth testing

Many tests are lost before the sample reaches the laboratory. Urine scooped off tiles, gravel or grass is contaminated with bacteria and debris, and allows neither a reading of the sediment nor a culture. Use a clean, dry container, or for a cat an emptied and washed tray with non absorbent litter. Collect in the morning where you can and get the sample to the practice within two hours, otherwise keep it in the fridge: beyond that, crystals form in the pot and bacteria multiply.

What colour alone cannot tell you

No colour names a disease, and perfectly ordinary looking urine rules nothing out: protein loss, glucose in the urine or early kidney disease cannot be seen. Colour is there to trigger a test, not to replace one. A dipstick, a specific gravity measured on a refractometer, a look at the sediment and, depending on the picture, a urine protein to creatinine ratio or a haematocrit give what the eye cannot. Only the veterinary surgeon registered with the RCVS who examines your animal can tie that together.

Questions to ask your vet

1. Could this colour simply be explained by concentrated urine?
2. Should the urine sediment be checked for blood or haemoglobin?
3. My animal is on a supplement or a medicine, could that colour the urine?
4. Was the specific gravity measured on a refractometer, and on which sample?
5. How should I collect the next sample, and how quickly does it need to reach you?

Why does my dog's urine smell of ammonia?

In the great majority of cases urine smells strong because it is concentrated, or because it has been standing in the air: the urea in it breaks down to ammonia, which is what gives a carpet or a litter tray soaked for a few hours that sharp smell. A dog that has drunk little, been running in warm weather or spent the night without access to water passes dark, strong smelling urine in the morning, and that does not indicate disease. What changes the reading is other signs alongside it: frequent and painful attempts to urinate, small amounts, drops of blood, licking, accidents indoors. A urine test with culture is then the only way to establish an infection, because the smell cannot.

Is dark yellow urine in my dog something to worry about?

Most of the time dark yellow urine is simply concentrated urine, from a dog that has drunk little, walked a long way in the heat or just spent the night asleep. What matters is not one dark sample but how long it lasts: dark urine for several days in a dog drinking normally, or alongside vomiting, diarrhoea, loss of appetite or dullness, is worth a consultation. The colour should also prompt a call if it turns orange or brownish green, or if yellow foam appears when the pot is shaken, because that raises the question of bilirubin. A dipstick and a specific gravity measured on a refractometer separate these situations within minutes at the practice.

Why is my dog's urine bright fluorescent yellow?

A vivid, almost fluorescent yellow is very often linked to a vitamin supplement, B group vitamins in particular, whose excess the body clears in the urine. It is harmless, it often shows up in the days after starting a supplement or a fortified food, and it fades when the product is stopped. Check what your dog is actually getting, supplements, functional treats, a food changed recently, and mention it to your vet. Bright yellow urine in a dog that is eating, drinking and urinating normally does not carry the same weight as dark yellow turning orange in a dog that is off colour, which does need examining.

Why does my dog's urine leave yellow patches on the lawn?

This is not a health problem but a question of soil chemistry. Urine delivers, all at once and over a few square centimetres, far more nitrogen than the grass can take up, so the blades scorch in the middle of the patch while the ring around it, at a lower dose, greens up more strongly. Volume matters as much as concentration, which is why the patches are more obvious with bitches and with dogs that empty the bladder in one spot. What works is watering the area heavily in the minutes afterwards, or training the animal to use a corner of gravel or bark chippings. Supplements sold against urine patches essentially work by making the animal drink more and so diluting the urine; changing the composition of your dog's urine to protect a lawn is not a sensible aim, and any product of that kind should be discussed with your vet before it is given.