The only difference between dog urine and human urine is that they come out of differing species.
Otherwise, it's next to impossible to tell them apart, unless you have the urine chemically analyzed. Like human urine, dog urine is most concentrated in the morning and then is mostly water later on. Also, dogs usually do not urinate as much as humans. Dog urine contains water, bacteria, ammonia, uric acid and dog hormones.
It's these hormones that are different from human urine. Any dog nose can smell these hormones to know the sex, remove pet urine odors from dog and cats health and even the breed of the dog that urinated. When the dog urine dries, it does so in tiny crystals that can release their smelly messages when they are moistened again from humidity or being sniffed through a dog's wet nose. The big misconception about dog urine is that it destroys lawns. It doesn't. Dog urine is mostly water and studies have shown that, over time, lawns with dogs in them do just as well as lawns without dogs.
Some European alchemists in the middle ages remove pet urine odors from dog and cats apparently thought one possible reason was that there was gold in urine. This led to fruitless, and possibly quite disgusting, efforts to extract that gold. The yellow color in urine is due to chemicals called urobilins. These are the breakdown products of the bile pigment bilirubin. Bilirubin is itself a breakdown product of the heme part of hemoglobin from worn-out red blood cells. Most bilirubin is partly broken down in the liver, stored in the gall bladder, broken down some more in the intestines, and excreted in the feces (its metabolites are what make feces brown), but some remains in the bloodstream to be extracted by the kidneys where, converted to urobilins, it gives urine that familiar yellow tint. (Here is a great diagram of some of these reactions, from the Boehringer Mannheim Biochemical Pathways at .) Urine is mostly water, which just has to be replaced. We excrete water not just to get rid of it if we have drunk too much, but primarily to carry away toxins that would otherwise build up in our systems. The important part of urine is urea (also known as carbamide), (NH2)2CO. The real waste product our bodies have to get rid of is ammonia (NH4+, when in solution), which is formed by the breakdown of amino acids -- the building blocks of proteins. But ammonia is so toxic that only tiny concentrations can be tolerated. So any ammonia in the bloodstream is rapidly converted to urea in the liver.
That urea is then removed from the bloodstream in the kidneys, and left in concentrated form in the urine (about 2% of urine is urea.) Ammonia is generated during the (breakdown) of amino acids in the liver. Other sources of ammonia include bacterial hydrolysis of urea and other nitrogenous compounds in the intestine, remove pet urine odors from dog and cats the purine-nucleotide cycle and amino acid transamination in skeletal muscle, and other metabolic processes in the kidneys and liver. The normal physiological concentration in blood is less than 35 micromol/l. A five- to ten-fold increase in this concentration causes toxic effects, especially on the central nervous system. Normal and healthy urine is pale yellow in color. The human body produces urine as a way to rid itself of harmful toxins, such as ammonia, which is broken down into urea by the kidneys, getting it ready for disposal. Urine also contains sugars, water, and urobilins. Urobilins are the broken-down products of bilirubin, which is itself the broken-down product of old blood cells. Bilirubin is what gives color to bile, bruises, and feces, and most bilirubin is gathered from the blood stream by the liver. From there, it is broken down by the gall bladder and intestines, and then excreted by the bowel. Some bilirubin, however, stays in the blood until it is picked up by the kidneys, where it is then broken down into urobilins and removed from the body in urine. Also known as urochrome, urobilins are the pigment that gives urine its yellow color.
Urine is usually pale yellow, remove pet urine odors from dog and cats but it can range from clear to a deep amber color in a healthy person. The level of yellow in the urine is determined by how hydrated a person is. A person who is very hydrated has more water to release through urinating, and thus has a lesser concentrate of urobilin in their urine. A person who is very dehydrated will have a much higher concentration, and thus much darker urine. Some foods, such as beets, may temporarily change the color of urine. Eating a lot of carrots, or drinking a lot of carrot juice, can turn urine orange. Asparagus can make urine much brighter in color, as can some vitamins -- usually vitamins C and B. Certain medications can also affect urine color, as can food dyes. An unusual urine color may also indicate a health problem. Brown or red urine could indicate a severe problem in the kidneys, for example. The best way to bring dark urine back to a healthier pale yellow is to drink several glasses of water or other clear fluids each day. Most health care professionals recommend eight glasses of water, although some people may need a little more or less. After a few glasses of water, the body should start to rehydrate and urine will return to a normal color. If the urine remains dark after a day of increased water intake, it may be necessary to be checked out by a doctor to make sure there is no underlying medical cause for the color remove pet urine odors from dog and cats.