Dogs and humans are both mammals, thus the overall chemical composition of their urine is remarkably similar. The urinary system of a dog consists of kidneys, ureters, bladder, urethra and genitals, including a prostate in males.
Urine is 95 percent water and 5 percent water-soluble organic materials and ions. The amounts of substances present in urine vary with time of day, diet and nutrition, but the chemical structure of urea is fairly constant.
The chemical structure of urea is written as (NH2)2CO. This means that two nitrogen-containing, ammonia-derived molecules are joined to a carbon molecule that has a double bond to an oxygen molecule.
Dog urine contains urea, creatine, uric acid, carbohydrates, enzymes, fatty acids, hormones, sodium, potassium, chloride, magnesium, calcium and ammonia.
When a dog smells another dog's urine, it can detect the hormones, such as estrogen or testosterone, that is present in the urine.
Disorders of the endocrine system can be detected in a dog's urine, including diabetes, Addison's disease and Cushing's disease.