Anemia is a defined as a deficiency of red blood cells (erythrocytes) in the circulatory system. Adult dogs are anemic when the concentration of red cells in whole blood is less than 37 percent by volume. The normal range is 39 to 60 percent. Red cells are produced by the bone marrow and have an average life span of 110 to 120 days. Old red cells are trapped by the spleen and removed from the circulation. The iron they contain is recycled to make new erythrocytes.
The purpose of red blood cells is to carry oxygen. Thus, the symptoms of anemia are caused by insufficient oxygen in the organs and muscles. Signs include lack of appetite, lethargy, and weakness. The mucous membranes of the gums and tongue become pale pink to white. In dogs with severe anemia, the pulse and respiratory rate are rapid, and the dog may collapse with exertion. A heart murmur may be heard.
There are three species of hookworms that afflict dogs. These parasites are most prevalent in areas of high temperature and humidity (such as the southern United States), where conditions are favorable for the rapid development and spread of larvae.
Hookworms are small, thin worms about one-quarter to one-half inch (.6 to 1.3 cm) long. They fasten their mouth parts onto the mucosa of the small intestines and suck blood and tissue fluids from the host. This can result in severe blood loss and malnutrition...
Anemia can be caused by blood loss, hemolysis, or inadequate red blood cell production.
In adult dogs the most common causes of blood loss are trauma, slow gastrointestinal bleeding associated with stomach and duodenal ulcers, parasites, and tumors in the gastrointestinal tract. Chronic blood loss also occurs through the urinary system. Hookworms and fleas are common causes of chronic blood loss in puppies.
Treatment: Treatment must be directed toward the cause of the anemia. Gastrointestinal bleeding can be detected by checking the stools for microscopic traces of blood. Urinalysis will pick up traces of blood in the urine that may not be visible to the naked eye. Other tests can also be used to determine the cause of the occult (microscopic) bleeding.
Hemolysis is an acceleration in the normal process of red blood cell breakdown. Red blood cells break down to form bile and hemoglobin. With severe hemolysis, these breakdown products accumulate in the body. Accordingly, in a dog experiencing an acute hemolytic crisis you would expect to see jaundice and hemoglobinuria (passing dark-brown urine that contains hemoglobin). In addition, the dog appears weak and pale and has a rapid pulse. The spleen, liver, and lymph nodes may be enlarged.
Causes of hemolysis include immune-mediated hemolytic anemia, congenital hemolytic anemia, infectious diseases (such as canine babesiosis and leptospirosis), drug reactions to medications such as acetaminophen, and poisonous snake bites. A number of bacteria produce toxins that destroy red blood cells, so hemolysis can also occur with severe infections.