There's no way to gaurantee they won't aspirate, but there are some things you can do to help prevent it..
First -- no gigantic "catheter-tip" syringes! In order to get a catheter tip syringe in far enough to keep them from spitting the liquid back out, you sometimes find yourself wanting to put the whole end of the barrel in their mouth... To illustrate how dangerous that is, open your mouth and try to swallow.
See how awkward that is? Now do it as someone's basically waterboarding you with something icky..
Not great, huh?!!
Definitely use an actual drench syringe for any substantial drenching.. Electrolytes, etc.... Drench syringes aren't that expensive, and they're MUCH safer for the animal as they can close their mouth enough to swallow freely..
Second -- keep the head level! You never, ever want to tip their head back when drenching. If you're using a drench syringe and put the bend of the nozzle right in the corner of their mouth, pushing the contents out slowly and steadily, they'll swallow involuntarily. There's no need to tip their head back to accomplish this. All that's liable to happen if you tip their head back is that they won't be able to swallow fast enough before the liquid runs down their windpipe.
Now, with all that said.....if I'm administering a few ml of something from a 6ml syringe (wormer, for instance), I just pop it in their mouth -- with their head level! -- and shoot it.. I've had them cough and sling their head a little bit on occasion, and I suppose they could aspirate...but an entire 6ml syringe full is still only 1/5th of the tiny little dose cup on top of your Nyquil bottle. There's just not much there.
Thank you!!! I so appreciate all the great info. I get from this forum!
I would never had thought to keep their head level.....but it makes sense. I picked up a drench syringe today at the feed store.
Thanks again!!