Technology is disclosed for a cat litter that can be used to diagnose feline medical conditions. A cat litter contains an additive, e.g., a chemical agent, such as a natural and/or synthetic agent, that changes in color when it comes in contact with cat urine or feces. Based on the color it can be determined whether the cat has a medical condition, such as particular illness. For example, if the litter turns yellow when it comes in contact with the urine, it can indicate that the cat is healthy. If the litter turns to a color other than yellow, e.g., green, it can indicate that the cat has some illness. The cat then be taken to a veterinary doctor for further diagnosis. The chemical agent aids in detection and diagnosis through interaction of materials that change colors to indicate reactions with specific chemicals, cells, molecules, DNA and/or materials. The technology can be implemented for medical diagnosis and detection—；for humans and/or animals.
