Many dog owners know that anemia is due to an iron deficiency, but many may not be aware of the fact that there are different types of anemia in dogs. Since dogs are meat eaters, and their foods are rich in protein and iron, anemia secondary to nutritional deficiency does not happen very often unless the dog is emaciated and suffering from starvation. In dogs there are two main types of anemia, regenerative and non-regenerative. In this article we will take a look at these main types of anemia in dogs and their causes.
Regenerative Anemia in Dogs
Regenerative anemia in dogs refers to anemia that is caused by excessive bleeding or the destruction of red blood cells, a process that is medically known as "hemolysis." The word hemolysis is composed by the word "hemo" which is the ancient Greek word for blood and the word "lysis" which means disintegration of cells, usually either by rupture of the cell wall or membrane.
What conditions can cause destruction of red blood cells? There are several such as immune-mediated hemolytic anemia, several tick-born diseases such as babesiosis, Heinz anemia caused by onions, disseminated intravascular coagulation and zinc toxicity from the ingestion of pennies minted after 1983, just to name a few.
Excessive bleeding in dogs to the point of causing anemia can be seen when dogs are victims of traumatic accidents or blood loss stemming from GI ulcers or cancers. A common cause of bleeding is the ingestion of rat poisons. Internal bleeding can go undetected until the dog develops symptoms of anemia such as pale gums, a fast heart rate and sudden weakness.
Newborn puppies are particularly predisposed to becoming anemic when their bodies are affected by parasites. Why is that? Because at this age puppies rely on milk, and therefore they have little iron to start with, and blood loss from parasite loads can therefore quickly make them anemic compared to adult dogs.
As the name implies, regenerative anemia indicates that the dog's body is trying to fix the condition (regenerate) and the bone marrow, the spongy tissue inside the bones where red blood cells are formed, is working. Therefore, this means that, once the underlying cause for the bleeding is addressed, there is hope that the bone marrow will provide support, by makings its own blood, explains veterinarian Dr. Will. Fortunately, most anemia types in dogs are regenerative.
Non-Regenerative Anemia in Dogs
Non-regenerative anemia in dogs refers to anemia that is caused by a decrease in the production of red blood cells and this is often caused by some abnormality affecting the dog's bone marrow, the spongy tissue inside the bones, which is where red blood cells are formed.
The process of the bone marrow manufacturing red blood cells is known as erythropoiesis. This term derives from the word erythrocytes, which is the more technical medical term for red blood cells.
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Non-regenerative anemia tends to often occur secondarily to other disease processes. Possible conditions associated in non-regenerative anemia in dogs include chronic kidney disease, chronic liver disease, hypothyroidism, hypoadrenocorticism. It can occur primarily when diseases and cancers directly attack the bone marrow.
As the name implies, the production of blood is disrupted and there are high chances that the dog's body will not regenerate or produce blood. Treatment is difficult since there is no support from the bone marrow in producing new blood. Fortunately, this type of anemia is less common.
At the Vet's Office
Your vet will asses your dog and determine whether he needs prompt supportive treatment. He will look for signs of anemia ans ask several questions about your dog's symptoms, when they started etc.
To determine the effectiveness of the blood marrow to produce red blood cells, your vet will have to run blood tests, in particular, a blood tests that's known as a reticulocyte count. Reticulocytes are immature red blood cells without nuclei that are produced by the bone marrow.
When dogs undergo excessive blood loss, or when red blood cells are destroyed by the immune system, the bone marrow should respond by increasing reticulocyte production, explains veterinarian Dr. Michael Salkin. By checking the numbers of reticulocytes, the vet may therefore have an insight on the bone marrow's ability in regenerating red blood cells.
The best way to calculate the absolute reticulocyte count is by multiplying the percentage of reticulocytes by the red blood count. The absolute reticulocyte count in dogs should be >100,000 in dogs, but some use >60,000 in dogs, explains Dr. Kenneth R. Harkin, a board-certified veterinarian specializing in internal medicine. Slight regeneration is seen in numbers around 150,000, moderate regeneration is seen with numbers around 300,000 while marked regeneration is seen in numbers above 500,000.
It's important to remember that the bone marrow takes about 4 to 7 days to start showing signs of regenerating blood cells after an acute case of blood loss. Treatment is based on the addressing the underlying cause.
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