Urine Tests - What Is a Urine Analysis?

A urine analysis (or urinalysis) is a collection of relatively simple tests that can be undertaken in practice. The tests assess the physical and chemical composition of the urine. Abnormal results usually indicate there is a disorder affecting either the kidneys and/or other parts of the urinary system. Other tests also provide information about potential problems in other organ systems or the presence of other problems, e.g. diabetes mellitus (sugar diabetes).

Urine analysis and serum biochemistry together provide us with a fairly comprehensive health assessment of the pet.

How do I collect the urine?

We will provide you equipment which allows you to catch a mid-stream urine sample and store it in a sterile container. If you have difficulty we may have to admit your animal in order to obtain a sample either by catheterisation or other methods. In the majority of cats your veterinarian may need to collect some urine directly from the bladder which is usually a painless procedure.

What happens if I am unable to obtain a urine sample?

Please contact us. If your pet will not cooperate we will admit for a short time in order to obtain a sample

What is involved in a urine analysis?

Broadly there are two types of test, physical tests and biochemical tests. 

Physical tests involve:-

1.  Assessment of colour and cloudiness (turbidity)

2.  Measurement of specific gravity (concentration)

3.  Measurement of pH (acidity)

4.  Microscopic examination of cells and any sediment (solid material) present in the urine

1. Turbidity.  Normal urine is pale yellow to light amber and is generally clear to slightly cloudy. Urine that is dark yellow suggests dehydration while very pale yellow or clear urine indicates that the urine is not being concentrated by the kidneys. Unusual colours, e.g. orange, yellow or brown, suggest that pigments are present in the urine and are an indication of other underlying disease.

Increased cloudiness is associated with the presence of blood, inflammation, crystals, mucus and/or other debris in the urine and in these cases further tests are necessary to analyse the sediment.

2. Specific gravity (USG) The USG of the urine is a measure of its concentration. The major function of the kidney is to maintain the body's water balance within narrow limits. Excess water in the body is removed via the kidney into the urine and the urine becomes more dilute. Conversely if the body is dehydrated the kidney conserves water by reducing the amount excreted in the urine and the urine more concentrated. Thus highly concentrated urine usually indicates some dehydration. Whether specific treatment is necessary will depend on whether other signs are present. Often the provision of drinking water is all that is necessary but on occasions the pet may need to be hospitalised for fluid therapy if dehydration is severe.

"The major function of the kidney is to maintain the body's water balance within narrow limits. Excess water in the body is removed via the kidney into the urine and the urine becomes more dilute."

Normally the first urine sample passed during the day is the most concentrated. If it is found that an animal repeatedly passes very dilute urine, particularly with early morning samples, further specialised tests are indicated.

3. pH. Urine pH is a measure of the urine's acidity or alkalinity. Normal urine of the cat and dog ranges from mildly acidic to mildly alkaline. Extremes of pH are more likely to be associated with disease. Urine pH can also be influenced by diet but it is more often a reflection of the pet's metabolic state. It can also be an indicator of infection and underlying disease. Regularly passed highly acidic urine (low pH) or alkaline (high pH) in itself needs investigation since in such circumstances pets are more prone to certain types of stone formation and can be susceptible to bladder infections.

Microscopic examination of urine sediment: Why is urine sediment examined?

Important information regarding the health of the animal can often be obtained from examination of the sediment. The most common features are red blood cells, white blood cells, crystals, bacteria and tissue cells from other portions of the urinary system. Occasionally parasite eggs can also be found but this is very uncommon.

a.  Red blood cells.  These may be present if the urine has had to be collected by techniques other than "free flow". Large numbers however can indicate bleeding which may be caused by conditions such as bladder stones, infections, coagulation problems or trauma.

b.  White blood cells.  A small number of white blood cells may regularly be found in urine samples but large numbers generally indicate the presence of inflammation in the urinary system. This is usually secondary to bacterial infection.

c.  Tissue cells.  An increased number of tissue cells usually indicates underlying inflammation, bladder stones, or prostate problems (in the male dog). If the cells are abnormal this may be an indication of cancer especially in the older animal. Further tests may be necessary

d.  Crystals. These are one of the most common abnormal components in urine sediment. They are often identified by their shape and colour. Some crystals are associated with specific diseases and their presence may indicate the need for further tests.

Chemical analysis: How is the chemical analysis of urine performed?

Today most chemical analyses of urine are carried out using a dipstick. This is a small strip of plastic with a series of individual test pads. Each pad measures a different chemical component of the urine and changes colour to reflect the amount of that substance in the urine. The stick is dipped in the urine and after a specified time interval the colour is compared to a chart which indicates the amount of that chemical present.

What substances are most commonly tested for in this analysis?

a.  Protein.  Protein in the urine is known as proteinuria and is abnormal in any dilute sample. Further tests may then be necessary, particularly the protein/creatinine ratio.

b.  Glucose.  Glucose is not normally present in the urine of healthy cats and dogs. A positive reading is usually the first indication that the pet is suffering from sugar diabetes (diabetes mellitus). However, small amounts of glucose may be found with some types of kidney problems.

c.  Ketones.  These result from fat breakdown. They can occur when fat is being used to provide energy needs, as in the case of an animal suffering sugar diabetes. However, ketones can also be found in animals subjected to prolonged starvation.

d.  Occult blood.  The occult (hidden) blood test is a very sensitive test for blood in urine. It is usually an indication of bleeding somewhere in the urinary system although it can indicate the presence of haemolytic anaemia resulting in haemoglobin (the red blood cell pigment) appearing in the urine or rarely the presence of muscle protein, myoglobin, if severe muscle damage has occurred.

e.  Urobilogen.  A detectable level of urobilogen in urine indicates that the bile duct is working with bile flowing from the gall bladder into the intestines. This is normal. Absence of urobilogen in the urine can indicate bile duct obstruction.

f.  Bilirubin.  This is a pigment that is produced in the liver and normally excreted from the body via the bile. Bilirubin is not found in the urine of healthy cats but small quantities are considered normal in the urine of dogs.