Possible Seizure???

Question
This morning I came downstairs while my 3.5 yr old Female
Boxer named Biscuit was eating.  She had stopped eating to
greet me.  She chased me a round our kitchen island getting
up on her hind legs a few times to check on my position.  
She started to slow a bit and when she went up on her hind
legs the final time she froze and fell on her side.  She
released urine as she laid still, legs locked straight out,
for a couple of seconds before I scooped her up and stood
her up on her legs.  She stood stiff as I stuck my fingers
down her throat to release anything that may have been
stuck in her throat.  I didn't feel anything.  Within
seconds she returned to her normal self.  Withing a couple
of minutes she returned to her plate to finish off her
breakfast.  She scared the @*#^ out of us.  Was this a
Seizure?  I envisioned seizures to include shaking...there
wasn't any.  She has no history of anything...yet.  We will
be going to the Vet by tomorrow but could you let me know
what we experienced with her.

Thanks,
Joe

Answer
I well know how scary such a thing can be!  It could be a few things - did you happen to notice the color of her gums?  It doesn't sound like a typical seizure, which includes shaking, thrashing and jaw snapping - but seizures can take on many different forms so that's not necessarily enough to rule it out.  Seizures also typically leave the dog "out of it" for some time afterward, and the gums are usually bright red, but again that's not always the case.

It does sound more to me like a heart-related syncopal episode; these are often confused with seizures, but they generally don't include shaking or jaw snapping (the legs do sometimes thrash as the dog tries to regain it's stance); the gums are typically very pale, grey or white; and the dog is completely back to normal within a few seconds of reviving.  Heart conditions are quite common in Boxers, so this is always a first thought when a dog passes out - if your vet doesn't hear a murmur or arrhythmia, you might consider visiting a board-certified veterinary cardiologist for a Doppler Echocardiogram and 24-hour Holter monitor - standard screening for any Boxers in a breeding program, and good for peace of mind even in non-breeding dogs.  

There are some other possibilities, as well - hypoglycemia, though if she was eating that's not as likely; an elongated soft palate; a heavy worm burden; anemia; and hypothyroidism are all candidates for fainting spells, as well as allergic reactions (though you'd generally see hives in that case).  

Good luck!