Urinalysis

Once we have collected the urine it will undergo 4 tests:

1. Color & Clarity: urine should be clear and light yellow in color. Dark yellow urine may be a sign of dehydration, very light yellow urine may be a sign of the kidneys inability to concentrate the urine. Red colored urine may be a sign of blood. Murky urine may contain inflammatory cells, crystals, protein, etc. 

2. Specific Gravity: this test tests the urine's concentration. One of the kidneys' tasks is to maintain the body's water balance. In a state of dehydration, the kidneys keep the water and the urine is more concentrated. When there is an excess of water, the kidneys allow more water to be excreted and the urine is more diluted.

Very concentrated or very dilute urine are not definite signs of a disease and we need to consider other clinical signs.

 When we see the urine is dilute in several occasions we will ask you to collect the morning's first urine, which is more concentrated. If the morning's first urine is concentrated enough and the pet does not show any other clinical signs we can consider him/her a healthy pet.

3. Urine Stick: the urine stick has pieces of special paper that change color as the result of a chemical reaction with different substances in the urine.

• Glucose – it should not be found in the urine. Presence of glucose in the urine can be a sign of kidney disease or diabetes.
• Bilirubin – it is formed in the liver and excreted in the bile. Healthy dogs may have trace amounts of bilirubin in their urine but healthy cats have none. Some liver disease cause bilirubin accumulation in the blood so it is excreted in the urine and shows up in the urine stick test.
• Ketones – they are formed when the body uses fat and fatty acids for energy. The presence of ketones in the urine is a sign of diabetes.
• Blood – a "positive" result on the stick often mean bleeding in the urinary system but can also mean breaking of red blood cells and release of hemoglobin.
• pH – shown how acidic or basic the urine is. When the urine is too acidic it is very likely that calcium oxalate crystals/stones will form. When the urine is basic there is a chance of infection and a likelihood of struvite crystals/stones formation.
• Protein – high levels of protein or the presence of protein in dilute urine may indicate kidney disease.
• Nitrite – nitrate, which is normally excreted in the urine, is converted by bacteriae to nitrite. "Positive" nitrite on the urine stick means the presence of bacteriae in the urine and, therefore, is an indication of a urinary tract infection (UTI).
• Leukocytes (white blood cells) – these cells are inflammatory cells of the immune system and are normally not found in urine. A "positive" stick result is a sign of UTI.

4. Microscopic Exam: the urine is centrifuged, the sediment is stained and then looked at under the microscope. During this evaluation we check what cells and other findings are in the urine. We will usually see red blood cells, white blood cells, crystals and bacteriae.

• Red Blood Cells – in a large amount they indicate bleeding in the urinary tract that can be the result of trauma, inflammation, stones, etc.
• White Blood Cells – their presence is an indication of an inflammation.
• Crystals – there are several types of crystals that differ in their composition and shape. Crystals may form as the result of different diseases, such as liver and kidney disease, some types of food that affect the urine's pH, the presence of bacteriae that change the urine's pH, certain drugs, etc.
• Bacteriae – during the microscopic exam we can see the bacteriae but cannot identify their exact species or what antibiotics they are resistant to. In order to get that kind of information we may want to send a urine sample to the lab for a culture and sensitivity test. This test consists of growing the bacteria found in the urine in the lab and then testing what antibiotics are most affective against them.

In summary, a urinalysis can give us a lot of information about the health state of the pet but very often further tests are needed in order to get an exact diagnosis. Also, sometimes there is a need to repeat the urine tests several times, for example when dealing with crystals.