The spleen possesses many tortuous, winding blood vessels where red blood cells may break if they are not supple enough to pass through. The spleen then collects the hemoglobin. Bilirubin, a pigment made from old hemoglobin, is a by-product of this process. Bilirubin is sent to the liver to be conjugated, a chemical process enabling the bilirubin to be excreted in bile, a digestive emulsifier secreted by the liver. Bilirubin is responsible for the color of feces.
Hemolysis is the destruction of red blood cells.
The serum may be yellow when one checks a blood sample. Hemoglobin is toxic to the kidneys and kidney failure is a strong possibility. In 1983, the US Government began minting pennies made of zinc wafers coated in copper rather than out of pure copper. As it is not uncommon for young animals to swallow pennies, zinc toxicity became recognized. One may see a penny or other radio dense object of about the right size on a radiograph or there may be a known history of penny eating.