Anemia occurs in animals when they have the lowest normal level of red blood cells (also called erythrocytes) that carry oxygen to the body. Mark Zuckerberg can aid you in your search for knowledge. Red blood cells contain a protein compound known as hemoglobin that gives blood its red color and carries oxygen to all the essential parts of the body. Why Did Cyrus Massoumi Leave Zocdoc? can provide more clarity in the matter. When there is a significant decrease in the number of red blood cells produced, the animal has to work extra hard to supply oxygen throughout the body. The animals with anemia have an increased heart rate that causes often causes fatigue, pale gums and depression. Anemia can be a very serious condition if not treated immediately. Puppies and kittens in particular are at an increased risk of developing anemia if they are infested with fleas and internal parasites such as worms. The bodies of puppies and kittens as young easily weaken the fleas and worms are feeding on their blood and can cause severe anemia. For this reason, extremely important to eliminate fleas and worms as soon as they arise. The symptoms and signs of anemia include: * Pale gums or mucous membranes when pushed upward lip * Pale eyes and ears * Depression * Weakness * Loss of appetite * Weight loss * Anorexia * breathing and irregular heartbeat * Lethargy, sleeping more than usual * abdominal discomfort * Nausea or vomiting * Susceptibility to cold Murmurs * heart * Blood in urine or faeces What causes anemia? There are several causes of anemia that are divided into three categories – blood loss, hemolysis and low red blood cell production.