Urine testing, also known as urinalysis, is one of the basic and extremely valuable diagnostic tools in veterinary medicine. It allows a rapid assessment of an animal’s health and can detect many diseases before any visible clinical signs appear. Urine analysis provides valuable information not only about the urogenital system but also about other organs and systems, such as the kidneys, liver or pancreas.
Why is a urine test carried out?
Urine testing is performed routinely in many situations. The most common are:
- Diagnosing kidney and bladder disease: it helps detect inflammation, kidney or bladder stones and renal failure.
- Monitoring chronic conditions: in dogs and cats with diabetes, hyperthyroidism (in cats) or chronic renal failure, regular urine analysis shows how well the treatment is working.
- Preventive screening (a “check-up”): in older animals or as part of routine examinations, it allows health problems to be caught early.
- Investigating clinical signs: when an animal has trouble passing urine, drinks more water or urinates in unusual places.
How to collect a urine sample
Collecting a urine sample can be a challenge. The following methods are the ones most often used:
- Free catch (natural voiding): this involves catching urine in a special container as the animal passes it. In dogs this is the simplest method. With cats you can make the task easier by using a special non-absorbent litter in the tray. The sample should be taken from the middle of the stream, to keep contamination to a minimum.
- Cystocentesis: the most accurate method, in which urine is taken directly from the bladder with a fine needle. The procedure is carried out by a veterinarian under ultrasound guidance. It is ideal for bacteriological testing, as it eliminates the risk of contaminating the sample.
- Catheterisation: this involves passing a catheter into the bladder. It is an invasive method, used mainly in animals that cannot pass urine on their own.
For dogs and cats alike, the sample should be fresh: it is best delivered to the laboratory within 30-60 minutes of collection.
What to watch out for when collecting urine
A clean, representative urine sample is essential to reliable results. Even slight contamination can lead to a wrong diagnosis and unnecessary treatment.
- Hygiene: always use a clean, sterile urine container, ideally one bought from a pharmacy or veterinary clinic. Yoghurt pots or jars from the kitchen are not suitable.
- Timing: the sample should reach the laboratory as quickly as possible, ideally within 30-60 minutes of collection. Storing it too long allows bacteria to multiply, cells to break down and the pH to shift, which can falsify the result completely. If you cannot deliver the sample straight away, keep it in the fridge for no more than 6 hours.
Which parameters are measured in a urine test?
A general urine test in dogs and cats measures a number of parameters that together give a comprehensive picture of the animal’s health. The most important of them, and what they mean, are set out below.
Physical parameters
- Colour: normal urine ranges from straw-coloured to amber. A darker colour may point to dehydration, while a reddish-brown shade suggests the presence of blood or bilirubin.
- Clarity: a healthy animal’s urine is clear. Cloudy urine may indicate crystals, cells (white and red blood cells, for instance) or bacteria.
- Specific gravity (SG): a measure of the kidneys’ ability to concentrate urine. A low value (very dilute urine) may point to renal failure or diabetes insipidus. A high value, in turn, may indicate dehydration.
- pH: this shows how acidic or alkaline the urine is. In a healthy dog or cat, urine pH is usually slightly acidic. Changes in pH may point to urinary tract infections (bacteria can shift the pH towards alkaline) or to urinary stones.
Chemical parameters
- Protein: a small amount of protein in urine can be normal, but a higher concentration (known as proteinuria) may point to kidney disease, inflammation or damage to the urinary tract.
- Glucose: glucose in the urine (glucosuria) is most often a sign of diabetes. It may also indicate a disorder of the renal tubules.
- Ketones: their presence may indicate ketonuria, which occurs for example in advanced untreated diabetes, in starvation or in disorders of fat metabolism.
- Bilirubin and urobilinogen: bilirubin in the urine may point to liver problems or to intense haemolysis (the breakdown of red blood cells). Urobilinogen is a product of bilirubin metabolism, and its level may suggest inflammation of the liver or bile ducts.
- Blood: blood in the urine (haematuria) indicates bleeding in the urinary tract or kidneys. It may be caused by injury, stones, infection or a tumour.
Examination of the urine sediment
- Epithelial cells: these come from the urinary tract and bladder. Large numbers of them may indicate inflammation.
- Red blood cells (erythrocytes): their presence confirms bleeding in the urinary tract or kidneys.
- White blood cells (leukocytes): a high leukocyte count (leukocyturia) indicates inflammation or infection of the urinary tract.
- Crystals: different types of crystal (struvite or calcium oxalate, for example) may indicate a predisposition to forming urinary stones.
- Casts: these form in the renal tubules and may indicate serious kidney disease.
- Bacteria: their presence in a sterile-collected sample confirms a urinary tract infection (cystitis).
