The cat had some blood work done recently, mainly because I might at some point in the future actually find a job outside of Canada, and I’d have to take her with me.
I just picked up the official document with the results of her rabies titer. Had a bit of a giggle-fit after seeing my cat’s name with my last name on the label. “Penny Amsen” just sounds funny. It would have been funnier, of course, if it said “Fluffy Amsen”, or “Whiskers Amsen”, but I prefer people names for animals.
The test result was very good. She had to have a rabies-antibody titer over 0.5 to be allowed to travel. Pen did great, and got 3.46 .
0.5 what? 3.46 what?
The form says “IU/mL”. mL I know, but IU is strange to me. I tried to look up how it converts to something I know, but it’s weird . IU stands for “International Unit”, and it can be either volume or weight, depending on what you’re looking at. So….moles? It has to be something linear related to a molarity, but I can’t find out how to interpret it. I found this but it gives the amount of units per ampoule, and is probably about vaccines for humans, not cats.
What’s inside my cat? What does 3.46 International Units of antibody against rabies per mL Penny-blood mean? All I know is that it’s 7 times more than she needs, so she’s all set to apply for official papers should she need to travel anywhere. Still, I paid $300 for this blood test, so it bothers me that I don’t quite understand it.
Now I’m just waiting to find out where I need to take her, and also still waiting for the fur to grow back in her neck:
They shaved a spot to take the blood sample. It’s where her hair is the longest (see: lions. No, not sea lions.) and it’s taking forever to grow back. This picture was the day of the blood test, so it’s totally bald. She was so freaked out when I touched her skin there =) She has fuzzy fur there now, but still very short.
Hmm, good question. Since 1 unit of restriction enzyme is the amount that will completely digest 1 µg of DNA in 60 minutes, maybe 1 unit of rabies antibodies is the amount that will completely protect from 1 ug of rabies virus particles in 1 hour :) Although a whole ug of rabies virus seems quite a lot…
Good on your cats immune system to make it to seven times the requirement though :)
Damn you and your tricky questions – my brief search turned up this hit which has the useful line:
_The definition of an international unit (IU) is generally arbitrary, technical, and eminently forgettable. _
As far as I can make out it is a measure of the neutralising antibody titre raised by the vaccine dose. There should be a correlation between the titre achieved (often measured in tissue culture) and the degree of protection afforded to your cat. Some vaccines are formulated to product a fully protective response in a single dose.
I should be meeting with an immunologist later today so, if I remember to, I’ll ask him.
Eminently forgettable, ha! The lab techs and vets probably don’t know what they’re measuring either…
I suspect it’s not “international unit” but “imperial unit”. Therefore, multiply by 2.242 to get the equivalent number of metric units. From there I think you can work the rest of it out yourself.
I am an idiot: the vet just called and I could have asked what “IU” means, but didn’t.
He called about paperwork. I can send my cat to my parents in Holland for at least a while if I end up moving, but need certain forms and stamps and things, and they have to be the correct ones. For every country the requirements are different, and we (the vet and I) have been prepping the cat for the country with the highest requirements, which is the UK. If she meets the UK requirements, she can go anywhere within Europe and North America (and I think also Asia and Africa and South-America, but not Australia – that is the hardest to get into if you’re a pet). So now he’s spending his evenings at home double-checking various entry requirements. Maybe I should also bring my vet if I move.
So now he’s spending his evenings at home double-checking various entry requirements.
Ah, the vet, not the cat. I see.
The cat is a “she”.
Sorry Eva, my immunologist friend had no answer for you, though vaguely indicated that I was probably on the right lines with ‘international unit’ and antibody titers…
That’s too bad.
It will just go on the list of mysteries about cats’ insides (together with the purr mechanics)
Dude. Wikipedia. It’s an arbitrary unit set by the WHO to make sure everyone is talking about the same thing (unsatisfying yes?). Which all sounds kind of silly to me, can’t they use Units or something?
I need to do the same things with my cats. But one of them is now on immune suppressing drugs so I’m guessing it won’t work for her, so we’re not quite sure what to do. The stuff I’ve read about the UK says you have to wait for six months after the test too (despite my country being rabies-free, grr), so I need to decide soon.
Oh yeah, and my vet keeps getting me and the cat mixed up so the bill is just as likely to be addressed to Mandy, and they call Boyd “Mr Edmunds”. Silly vets.
Derek Bangham published a comprehensive history of biological standardisation – I think it is on the web available for download but can’t locate it right now. A shorter history is available.
Henry Dale and NIMR were very active in establishing biological standards, ultimately giving rise to what is now NIBSC.