Monday, February 23, 2009
By Dr Basil Sands
How often have you heard of a friend or family member taking their dog to the veterinarian only to be told that their dog is anemic? In the Bahamas many things can cause anemia: fleas, hookworms, trauma, kidney disease, ehrlichiosis, among other factors.
Anemia is a shortage of red blood cells which pick up oxygen from the lungs and transport it to all the cells in the body. Many persons think anemia is a disease in itself, but it is not. It is a symptom of a disease. Mild anemia usually is not an emergency that warrants a blood transfusion. Rather it is a signal to determine the cause of the anemia and hence treat the underlying cause.
(A note about blood transfusions: There is no available blood bank for dogs in the Bahamas. Dogs have different blood types than people. However, unlike people, dogs do not have performed antibodies against other blood types, so in an emergency, a dog that has never had a transfusion before can receive a different blood type than his own. After the first transfusion, future transfusions would need to be matched with his own blood type.)
How does a vet determine whether your dog is anemic? As a result of his training he can clinically determine whether a dog is anemic by the color of his mucus membranes. Other than that he can obtain some blood and do a hematologic test (examination of blood and its components).
The packed cell volume (PCV) is the percentage of the blood by volume that is made up of red blood cells. The normal PCV of a dog is about 35 to 45 percent. Dogs with a PCV below 35 percent are considered anemic.
The causes of anemia in the Bahamas as mentioned earlier are parasitic: fleas, hookworms, whipworms; infectious diseases, such as Ehrlichiosis; toxins such as lead; or trauma from lacerations or dog fights.
Anemia is almost never the result of an iron deficiency. Iron is needed to make hemoglobin, the oxygen carrying compound of red blood cells, but the body recycles and stores iron efficiently. Anemia indicates a breakdown somewhere in the supply and demand for red blood cells. For a dog to become anemic the red blood cells are either being replaced more slowly (e.g. kidney disease, bone marrow suppression, Ehrlichiosis) or disappearing more quickly than they should be (e.g. blood loss, parasites, and trauma etc.)
The supply center of the body to produce red blood is in the bone marrow. Problems that can hamper the bone marrow ability to produce a sufficient number of red blood cells include chronic illnesses (kidney disease), poisoning, chemotherapy, certain drugs and cancer of the bone marrow (e.g. Leukemia).
When there is a demand problem the red cells disappear from the circulation more quickly than normal. The blood loss can be obvious, as from bleeding from a wound or nearly invisible. Hidden blood losses might include bleeding into the digestive tract from a stomach ulcer or a heavy hookworm infection.
Red blood cells can even be destroyed right in the blood vessels by a variety of problems, including the tick borne diseases, ehrlichiosis and babesiosis; immune mediated hemolytic anemia, a heavy infestation of heartworms, certain toxins. Your veterinarian will be able to run tests and tell you whether one of these demand side problems is responsible for your dog's anemia.
There are certain toxins that can cause anemia as well. Onions, pennies, diaper rash ointment and Tylenol are four of the most common household items that can poison red blood cells and cause anemia. Because your puppy will chew on or eat anything and everything, your vet will ask you certain questions to rule out the causes. Onions and garlic if eaten in large amounts can damage the hemoglobin in the red blood cells making them unable to transport oxygen.
Pennies and diaper rash are two common sources of Zinc, which can destroy red blood cells. Lead can also attack red blood cells. Dogs can ingest lead if they chew on fishing weights, paint, and caulk, foil collars from wine bottles or even old linoleum floors. Tylenol is acetaminophen, which in large doses damages the hemoglobin in red blood cells and breaks up the cells. Remember Tylenol does not work well in dogs as a pain reliever anyway, so avoid Tylenol at all costs.
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