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Canine Autoimmune Hemolytic Anemia (AIHA & IMHA) - PCV tests
| Hi everyone. I have a question about PCV tests. How are these done? I heard that they put the blood in some kind of a machine and the machine "shakes" it. The reason I ask - every Thursday Mia's blood is taken and PCV checked. It has been 8, 3, 25, 25 again, 27 and 34. Today it was 30. The vet told me that last week's test, which was 34, was done differently than today's....... what does that mean?? I had a really bad day at work and didn't even want to open my mouth to ask any questions because I was very upset that they haven't been testing the exact same way every time. Now, I really don't know what her level is. We have started reducing her Pred a little, but now I am very scared in doing that. So, how many way's are there to test PCV...????? Thanks, Liz and Mia |
| Liz Nashville TN |
| Hi Liz, One way is done right in the office where yes they do spin and shake it the other way is to be sent out to the lab and have them do the testing. We used to have Holly's done in the office, but found to many times it varied, so now it is always sent out to the lab to be more accurate. Of course cheaper in the office then being sent to the lab. Hope this helps. Linda |
| Linda Sapphire |
| Hi Liz, Good question and something you should understand. There are two ways that this test can be done. Both start with a blood sample that is taken with a syringe that contains a special fluid in it. The simple way and the way it was done before computers is to put a small amount of this blood into a very small tube, a little larger than the size of a large length of pencil lead. They put this little tube into a machine that spins the sample. After a certain amount of time the red stuff in the blood separates from the clearer whiter stuff. The red stuff settles to the bottom. They put this little vial against a chart and compare where the top of the red stuff is against the numbers on the chart and from that they obtain the PCV or packed cell volume. This is a very accurate test because it is done visually. I always suggest that owners on this list request this test to be done in addition to the CBC when they are at very low numbers or are trying to determine if they need to make a med dosage change. My vet charges me $8 to do just this test. The other way this test can be performed is with an automated analyzer. If you are doing a complete CBC complete blood count, this will be used. The sample vial is inserted into the machine and the machine spins the vial and then uses computers and analyzers that look at shapes, colors, densities etc to sort out what kind of cells it is looking at and what percentage of those kinds of cells are in the frame of reference. There can be inaccuracies if the machine is not calibrated perfectly. There are also things that can happen to blood that make some of the things the computer sees to be mistakenly identified or misinterpreted. In general when you see HCT it is hematocrit and is the result of this kind of a test. It is, in essence, pretty much the same thing as PCV. However, these tests are extremely sophisticated and can tell vets marvelous things that are very important They are a very very good thing to have done! Your vet can often interpret things that seem slightly out of norm on the results. Sometimes the fault of a mistake in a test starts with an improperly handled blood sample! Your dog can be dehydrated making the sample not really accurate. The cells can be damaged when they are drawn into the syringe or if the tube is not handled carefully. The tube can sit around too long and the blood can coagulate. The dog may have had fatty food too close to the blood draw and the sample is cloudy. Never be afraid to ask about things like this. I think most vets and techs are often very willing to explain this kind of thing if they are not too busy. I hope this has helped you and I am very happy that you are seeing much higher numbers now! Maybe you will see the pcv continue to rise up to the high 30's soon! Patrice |
| Patrice NYS |
| Patrice, What a great answer. I've never had the specialist explain how the PCV test is conducted and, while it's still hard for me to take it all in, I now have a clearer picture of what's going on. I just didn't realize that all those things need to be taken into consideration, i.e., eating fatty foods, etc. Thank you so much and please continue to educate us on all these matters that concern our little ones. Karen |
| Karen NC |
| Patrice, thank you for including the information about eating close to the time of the blood draw and dehydration affecting the results. My vet mentioned neither factor -- I'll be sure and remember this before we go in again. You are fortunate to be charged only $8. Crista |
| Crista Arizona |
This thread was discussed on 24/10/2008
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