If the body is not working properly, small amounts of substances not normally present may be found in the urine or substances normally present may appear in abnormal amounts.
- The presence of glucose may indicate diabetes (see above).
- Urine with red blood cells in it is called haematuria, and may indicate inflammation of the kidney,or urinary tract, cancer or a blow to the kidneys.
- Sometimes free haemoglobin is found in the urine. This indicates that the red blood cells in the blood have haemolysed (the membrane has broken down) and the haemoglobin has passed into the kidney tubules.
- The presence of white blood cells in the urine indicates there is an infection in the kidney or urinary tract.
- Protein molecules are usually too large to pass into the kidney tubule so no or only small amounts of proteins like albumin is normally found in urine. Large quantities of albumin indicate that the kidney tubules have been injured or the kidney has become diseased. High blood pressure also pushes proteins from the blood into the tubules.
- Casts are tiny cylinders of material that have been shed from the lining of the tubules and flushed out into the urine.
- Mucus is not usually found in the urine of healthy animals but is a normal constituent of horses’ urine, giving it a characteristic cloudy appearance.
Tests can be carried out to identify any abnormal ingredients of urine. These tests are normally done by “stix”, which are small plastic strips with absorbent ends impregnated with various chemicals. A colour change occurs in the presence of an abnormal ingredient.