As a veterinarian, Leonard often gets frantic calls, particularly in the winter, from horse owners who believe that something is seriously wrong because their animal’s urine is red. Although red urine occurs throughout the year, it is most noticeable against the pure white snow.
We awoke to snow the last several mornings. When Leonard and I went out looking for tracks in the snow yesterday I noticed red urine outside of a vole hole. Horses are not the only animals with red urine.
Indeed, liver disease, the destruction of red blood cells in the body or other medical conditions can cause the urine to turn dark or red. However, as with most red horse urine situations, the red color outside of the vole hole is not indicative of a medical condition.
Urine contains minerals, proteins, vitamins and other metabolites. Depending on the diet (quantity and quality) more or less of these components may be in the urine. In addition, depending upon the availability of water, the urine may be more or less diluted. The less dilute the urine and the more metabolites that are being flushed from the body, the darker the urine.
When certain plant porphyrins and enzymes are metabolized they cause the urine to darken. In addition, when the urine is exposed to oxygen it turns a darker color, often red.
What at first appears to be the blood of a small rodent killed outside of its burrow, or an ill vole (or horse) with blood in its urine is actually urine that is red (or dark) because of protein or metabolites, concentration or exposure to oxygen.
This vole burrow with red urine outside the entrance was photographed on our property in Lookout CA.