"Paleness" refers to the condition of being noticeably lighter in color than usual, often describing the skin when it appears pale or lacking color due to various reasons such as illness, shock, or fear. Full definition
It gives red blood cells their colour (which is why iron deficiency anemia is often characterized by paleness of the skin). (easybabylife.com)
The body fails to generate enough healthy blood cells to overcome a progressive loss of RBC's in circulation, thus paleness in the soft tissues and anemic symptoms are therefore exhibited. (dog-health-handbook.com)
Although marked anemia causes paleness and a rapid pulse, the color of your pet's tongue or its heart rate at a veterinary hospital are not a good judge of anemia. (2ndchance.info)