My nine-month-old guinea pig’s pee is dark orange—almost red—but the vet says there is no blood in his urine. I’ve heard that guinea pigs can have strongly discoloured urine but seeing it always worries me. Is this normal?
It is true that guinea pigs, like most herbivores, can have very dark urine. This is likely due to their digestive system producing a pigment called porphyrin— it is a derivative of the breakdown of protein in their diet within their liver. High protein and calcium in their diet can result in increased porphyrin in the digestive system, and hence lead to increased intense yellow, orange, or even red pigments in the urine. The pigments get darker when the urine oxidises due to exposure to air.
Although your vet confirmed there’s no blood in your guinea pig’s urine, I do understand your concern upon seeing such intensely coloured urine. It is good to ensure sufficient water intake, at least 50 to 100ml daily per guinea pig. With increased water intake, it can help with hydration and also dilute the urine pigments of porphyrin. Also ensure that you give a good supply of green leafy vegetables and vitamin C daily. Try to choose vegetables and pellets that are not too high in protein and calcium. Do not give too many treats that main contain colouring and preservatives. There should be a healthy range of fresh vegetables, hay and pellets to ensure good digestive function. Timothy hay is best, as it’s low in protein and calcium as well; orchard grass and botanical hay are also acceptable. Please avoid alfalfa hay and oat hay, especially after your pig has reached adulthood at 10 to 12 months.
There are cases of senior guinea pigs with weak liver function developing heavily stained and pigmented urine. In such cases, the senior pigs will need to have comprehensive blood tests and x-rays to investigate both liver and kidney functions. Repeated urine tests should be done to keep track of possible secondary urinary tract infection in these old pigs. Such patients will require fluid therapy and long-term supplements to keep them comfortable and pain-free.