The ELISA (enzyme-linked immunosorbent assay) is a test which uses color change and antibodies to identify a substance. An indirect ELISA is one of three ELISA tests.
Urine varies in appearance, depending principally upon a body's level of hydration, as well as other factors. Normal urine is a transparent solution ranging from colorless to amber but is usually a pale yellow. In the urine of a healthy individual the color comes primarily from the presence of urobilin.
The normal color of urine from rabbits is yellow. Sometimes the urine can become red, pink, brown, or orange. This condition, often simply called red urine, can occur in healthy rabbits as well as those who are ill.