Blood testing

Re: Blood testing

Wren — Thu, 11 Apr 2013 10:34:15 GMT

I have the tail horizontal, put index finger of left hand at the point I want to insert needle and run needle along it. Although I did quite often spike myself! Needle goes into tail at about 45 degrees. It is harder in cold weather (peripheral vasoconstriction I assume). You must hold the tail yourself, not have the farmer do it. Wear gloves too - took me years to work that one out!

One of the happiest days of my life was the day I got the letter from DEFRA telling me that they'd ceased Brucellosis testing and I would no longer have to spend all winter with numb hands, covered in cow shit (they have an uncanny knack of filling the pocket on your parlour top while you're getting the sample), running needles into my own fingers and getting kicked all whilst trying to hit a 2mm vein blind on a moving target.

Re: Blood testing

Michael Woodhouse — Wed, 10 Apr 2013 18:14:38 GMT

Mariette, I find that they do not react with the tail as close to vertical as possible (can be next to impossible with a mature stock bull) and I find landmarks easier to identify as I am quite tall, If the tail is horizontal (like with a stock bull) then I have to twist round to see my space. If they bleed slowly lower the tail. We (sadly) have masses of surplus scrapie testing needles and they are all 20G for some reason and then tail position is much more important.

In terms of re-using needles - it depends on the test I am doing. Obviously not if a PCR, but I see no problem with conventional serology where the results are expressed as a dilution or percentage positive.

Eg toxo bloods in sheep, IIRC 1/32 = inconclusive and 1/64 positive. 5ml vaccutainer. The tiny drop in the needle cannot be 1% of that but assuming it was it would not affect the result if you do the sums.

Disease testing for export, new needle. Scrapie DNA. All new needle. New farm, new needle.

What do you do if injecting a batch? I will continue to use the same needle to do a batch of cows with prostaglandin. Same if vaccinating, treating a group with Micotil etc. Unless it becomes blunt, bent or contaminated. I PD multiple animals using the same glove. They milk cows using the same cluster.

Re: Blood testing

mariette asselbergs — Wed, 10 Apr 2013 16:21:55 GMT

I would not use the same needle for different animals if I was collecting blood for serology. I am sure you would have a VDS case if there was any doubt about the results.

Also I am surprised that you work with the tail vertical (bent up extremely) or do I misunderstand this? I work with the tail horizontal and the needle going in straight upwards and the needle/vacutainer hanging from the tail while filling. I find that if you bend the tail far upwards the vein seems to be squashed easily and more difficult to hit right.

Mariette

Re: Blood testing

Braden Collins — Wed, 10 Apr 2013 14:24:20 GMT

The only thing I can add to Michaels advice is to use your arm as a lever to elevate the tail. I'm right handed so stand to the left side of the cow (I never stand behind as you will get kicked. It fou stand to the left and either tuck in behind the bar of the crush or in tight against the leg you're safer) and use my left arm like a lever. It's hard to explain without showing, but I will bring my arm down from above the tail, grip the tail at a level that I can put the middle of my forearm on the tail base, then by dropping my elbow I lever the tail up. I find this much less tiring if you have to do large numbers, and it maks it easy to stand to the side where you are safer.

Re: Blood testing

Neil Wheadon — Wed, 10 Apr 2013 14:07:22 GMT

1) Pull the rubber guard off the needle before you use the needle. All it does is add resistance to pushing the tube onto the needle when you're hopefully in the vein, meaning you'll move the needle when you've just caught the edge of the needle.

2) Angle the needle, so that it does go perpendicular to the vein, more trying to run along it. I do the same with cat jugulars, bend the needle 10 degrees or so, so you are running up the vein, decreasing the chance of going through it.

3) Patience. If it's dripping gently into the tube, it will probably fill. Talk about the weather, lack of forage this year and milk prices rather than fiddle with the needle.

Good luck, we've all been there, you get good days and bad days.

Neil

Re: Blood testing

David Shepherd — Wed, 10 Apr 2013 13:08:29 GMT

Michael's advice is excellent; difficult to describe without demonstrating but he has done a good job. Just to add one tip I find useful; place your index finger on the midline ventral tail in roughly the position you want to insert the needle, with the needle resting against your finger, then slide the needle along your finger and through the (cow's!) skin. This enables you to guide the needle in more exactly.

This is all easier if you have largish hands like I have; have demonstrated before to female students with small hands and they find it difficult to hold and manipulate needle/holder/tube all in one hand. If that applies to you I'm afraid you may have to find an alternative method that works. Gets easier after the first 10,000 (!)

Also as noted above, occasionally you get boxes of tubes where the vacuum has gone. I also recall many years ago a batch of needles with no hole through the middle!

Re: Blood testing

Mark Hedberg — Wed, 10 Apr 2013 00:17:17 GMT

[quote user="Michael Woodhouse"]

Pink needles are your friend.

[/quote]

Worth their weight in gold in SA practice too :) (not blood sampling, just really useful and multipurpose.)

Re: Blood testing

Michael Woodhouse — Tue, 09 Apr 2013 23:20:29 GMT

For bleeding either cattle of sheep I think a 18G 1" needle is preferable (pink hub). If you get the ones with the rubber shroud, pull them off.

For a right handed operator

take tail in left hand as near vertical as possible (100X harder if a farmer tried to 'help' and hold tail)
Hold vaccutainer holder between thumb and index finger using little finger to support vaccutainer
I usually go 2 or 3 vertabrae from the anus insert the needle all the way (or until you strike bone)
MUST BE MIDLINE
Flick tube onto needle
If no blood draw backwards until it flows.
If the flow is slow lower the tail
If you need 2 tubes you can hold the extra tube between your 3rd and 4th finger but you then have a good handful.

If you are doing serology and the needle stays clean and doesn't hit bone it will use it for maybe 5 cows. If you hit bone it will burr and you must change it. If you are doing any sort of PCR test new needle per cow.

Biggest mistakes I see when students try - not getting tail straight. Not aiming between vertebrae. Pushing vaccutainer forwards onto the needle before stabbing the cow. You really need to stand behind the cow.

The only time I will let the farmer hold the tail is if we are bleeding cows at the time of a TT test and there's a lot of climbing involved to get to the back of the crush. It is a lot harder.

If you keep vaccutainers in the car for a long time they can lose their vacuum. Just keep what you need for day to day use (not a whole 50 tube field kit!)

Pink needles are your friend.

Re: Blood testing

John Flynn — Tue, 09 Apr 2013 21:20:52 GMT

A change from vacutainers coming with a needle on both ends (i.e. to go into cow and to go into vacutainer) saw me struggle more than I remembered... I think it was because I was used to putting needle into cow, then inserting vacutainer on to other needle and if had missed, then could take vacutainer off needle while maintaing the vacuum, remove needle from cow and re-position - I wasn't actually conscious I was doing this and had to consciously remember that once vacutainer inserted on then needle had to stay in cow otherwise vacuum was lost when go tthe sets with 'safety' plastic-rubber things instead of needles to enter the corresponding vacutainers - if they were removed then the vacuum was blown.

Re: Blood testing

karen jones — Tue, 09 Apr 2013 21:13:09 GMT

Have you checked the vacuums are ok in the tubes? I ventured out and blood sampled some cattle for bvd the other day and found that half the tubes had no vacuum and sucked blood out of them with a syringe. Make sure the tail is straight and the animal is not moving about too much and like all things practice helps. When I first qualified we spent hours blood sampling cattle for brucellosis. Also some days you can't get veins whatever you do !!