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Dogs - Anemia: Inadequate Red Blood Cells



Bone Marrow Suppression
Blood sample in a PCV tube being read against a chart

A simple measurement of red blood cell count is called the packed cell volume or PCV. The packed cell volume is an expression of the percentage of the blood’s volume which is taken up by red blood cells. It can be measured using only a drop or two of blood and can be done while you wait in any veterinary office. The sample is spun in a machine called a centrifuge to separate the red cells, white cells, and serum. The blood tube is then read against a chart to get the packed cell volume. Hematocrit or HCT also measures the volume of blood as red blood cells but uses a measure of hemoglobin to determine it. Practically speaking, PCV and hematocrit measure the same thing.

                   Normal PCV            Normal HCTDog             37 - 55%                  43.3 - 59.3%
Cat              24 - 45%                  29.3 - 49.8%

What can we do?

  • The injections can easily be given at home.
  • An oral iron supplement must be given simultaneously so that the bone marrow will have the building blocks necessary to make red blood cells.
  • Packed cell volume must be monitored weekly until the patient stabilizes so the patient will need frequent veterinary visits at least at first. If this monitoring is skipped, it is easy for the red cell count to become too high, thickening the blood and causing high blood pressure (which in turn creates more kidney damage in addition to other problems).
In a presentation by Dr. Sheri Ross at the 2006 meeting of the American College of Veterinary Internal Medicine, she noted that in one study of dogs and cats with naturally occurring kidney failure, 2 of 3 dogs treated with erythropoietin for greater than 90 days and 5 of 7 cats treated for greater than 180 days developed refractory anemia that was attributed to anti-erythropoietin antibodies. A clinically significant immunologic reaction to erythropoietin has been reported to occur in 20-70% of treated veterinary patients. A more commonly published statistic is that antibody production is a problem in 30-40% of pets using human erythropoietin but this complication poses a sobering thought. It is important not to use this hormone at the first sign of anemia but wait until it is really and truly needed.

Is Darbepoetin better than Erythropoietin?
Darbepoetin is a synthetic hormone meant as an improvement over the natural hormone, erythropoietin. The synthetic version lasts longer and is less antigenic (less likely to create any erythropoietin antibodies). Cost is similar to erythropoietin and since most veterinarians have experience with erythropoietin, this is what tends to be prescribed. Furthermore, dosing for animals is still being worked out though there are some guidelines based on human conversions between darbepoetin and erythropoietin. It appears that the changes made in the amino acid sequence have made darbepoetin less likely to generate anti-erythropoietin antibodies but in a patient that is already having a problem with antibodies, darbepoetin is close enough to EPO to be inactivated as well.



How do we know there is Stomach/Intestinal Ulceration?



What can we do?




Reducing stomach acid helps reduce pain and bleeding when the GI lining is ulcerated, at least in the stomach. Omeprazole is probably the strongest antacid for veterinary use but famotidine tends to be preferred because of its additional ability to antagonize parathyroid hormone, which is a uremic toxin and an elevator of blood phosphorus.



Pets coming to the vet’s office in Stage IV or late Stage III kidney failure are often dehydrated. A typical scenario is a pet who had been drinking lots of water and eating fairly well suddenly stops eating and is listless. Possibly it is even noticeable that the pet has lost weight (though this is often erroneously attributed to age). The owner waits a day or two to see if the pet will start eating again and get better on his own and when that does not happen, the pet is brought to the vet. Once the diagnosis of kidney failure is made, fluid therapy will be recommended, possibly fairly aggressively to drive the toxin levels down quickly. Unfortunately, the fluid therapy that is so helpful for driving toxin levels down will also dilute the blood and drive the red blood cell count down.

This is not a big problem if the patient is not particularly anemic to begin with but if the patient is already low on red blood cells or if fluid therapy is aggressive, by the end of hospitalization or even in the middle of it, the patient may be feeling the effects of the low red cell count.

What can be Done?
One choice is to be less aggressive with the fluid therapy though this means a longer time to get to a livable toxin level. Another choice is the use of erythropoietin as above, possibly in addition to a less aggressive fluid administration rate. Using erythropoietin helps at least increases the red blood cell production to balance the dilution that comes with rehydrating the patient.
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