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RE: [RC] red cells - heidiSo here's a question, are horses red blood cells larger than humans?No, they're smaller. Human rbcs have an MCV (Mean corpuscular volume) of approx 90; I believe equine rbcs have an MCV of about 60. (Heidi?) I can't speak for humans, but yes, 60 is actually on the high side for horses. If horse blood is left standing still, horse RBCs do tend to "stack" and therefore settle out much more quickly than other species, though--handy thing if you need to harvest or test plasma and don't have a centrifuge handy. But that doesn't affect the ability to draw circulating blood through a needle. Blood is somewhat viscous, which DOES make it tougher to draw through a really tiny needle (such as a 25 or smaller) but that's true of all species. The viscosity is one reason why one of my vet school equine professors would absolutely have fits if anyone tried to do an IV injection on a horse with anything less than an 18-gauge needle--if you accidentally poke a 20-gauge into an artery, the viscosity is sufficient that the blood coming out will not pulse, whereas if you accidentally hit an artery with an 18-gauge, the blood coming out will pulse beautifully. That's a habit that has stuck with me to this day, and although I know many vets will inject IV meds with a 20-gauge, I still shudder when I see it done. (OTOH, drawing smallish amounts of blood--say, just a tube-ful for a Coggins test or something--with a 20 is no problem and the horses fuss a bit less.) Heidi =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Ridecamp is a service of Endurance Net, http://www.endurance.net. Information, Policy, Disclaimer: http://www.endurance.net/Ridecamp Subscribe/Unsubscribe http://www.endurance.net/ridecamp/logon.asp Ride Long and Ride Safe!! =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
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