Tapeworm saliva test question

[Lulu44]

Started a new worming programme and have been given a saliva test to do which I haven't done before.

So the instructions strongly emphasise no water or food for at least half hour before doing the test, so would this mean if any older feed/grass gets on the test its then void?
Trying to get my head around how to do it as my boys on grass 24/7 and I have nowhere to put him where he can't eat anything!
I'm assuming the swab needs to be wet but clean so anything else on it would mean I'd have to retest? At £20 a test I kinda want to get it right first time lol

Tie him up with nothing for 40 mins and swish out his mouth with a syringe of water

And if you have nowhere to tie I guess walk him around! We usually do it after riding but the swab still often looks a bit dirty and there will be bits of grass on it and it hasn’t been a problem. Always seems to take ages to get the sample as well!

Can't you just worm him??

I didn't bother washing the mouth out (probably should've looking back) and the test worked fine and showed my horse as positive 😬 Is this equisal?

Thank you, probably just over thinking it all lol.
Yes it the equisal one

I tied up, really annoying test I thought