Help! Seizure, HYPP, or what?? Think Chanti just had one :(

Ok, scared to death right now, about to start crying First the colic scare Friday night, now this!
I was down at the barn, Sundance was tied to his post closest to the tack ropom, Chanti's rope was just slid through the ring and not tied. I had finished brushing her, then I used the rasp to trim up her front hooves a bit and then I brushed Sundance down and trimmed one of his front feet. I moved over to the other side of him to get his other foot and Chanti swung her butt toward him and I went over to pull her up because that makes Sundance nervous, and as soon as she stepped up, she did this leaning sideways deal, her eyes got real big, her head went up, she was falling sideways and she went backwards, hit the post Sundance was tied to, then fell sideways towards the middle of the barn and fell down on her side. Her legs were stiff, and I was just thinking "Oh God, she's going to die!!"
She never appeared to lose consciousness and she got up, shook the dirt off. She was breathing a little heavier, and kept lifting her right front leg and setting it down. She yawned real big and after a few minutes she started walking around.
I was shaking, about ready to cry(still am) because she has never done anything like that.
My first thought was really HYPP but as far as I know she doesn't have Impressive in her and like I said, it's never happened before.
I am so so worried about her.
I'm not sure it was a seizure, but don't know what else would make her fall over.
What does this sound like to ya'll?
I'm going to call the vet tomorrow and see what all tests they can run and how much it'll cost and if they take payments because I know we can't afford to pay in full :(
I have never been so scared in my life.
I can't think of anything different. Exercise isn't any different, she hasn't had any injury to her head that I know of, but it seems this year it's been really hard to keep weight on her. She's dewormed regularly and normally she stays fat all the time.
I'm thinking I should definitely have a CBC done on her, and perhaps the HYPP test, but again, she's never shown any symptoms and she isn't even heavily muscled.
I'm just so worried and scared. She's my forever horse, I don't want to lose her.

Was she sweting? Could it possibly be a shock reaction?

This does not sound like a seizure. I am starting my 4th year of veterinary school in a month and we are studying seizures right now- they are very dramatic and involve a lot of paddling and very frequent loss of bowel and bladder control. They have what is called a "post ictal" phase where they will seem dazed and "out of it". This absoultly does not sound like an HYPP episode either, and the vet will be able to send off a very simple test for her genetics to determine if that is even a possibility for her. I am going to go read up your thread on the colic scare but I wanted to ease your mind that this very bizarre episode does NOT sound like seizure or HYPP. I will hunt around and see if I can find some of the videos we were watching of horse seizures, it is very dramatic and like I said that post-ictal phase is very helpful to deterimine if that is what is happening to your girl.

That would be so helpful! Thanks! :) I started searching youtube for videos of horses having seizures and I found one where the mare just kept circling one way, kinda leaning, and she'd back up, then circle again, but Chanti's episode of whatever it was was much worse. She started out going sideways, slammed into the wooden post and crashed around before she fell on her side. She hurt her leg, the right front which is the one that she's been showing off and on lameness with., She has some heat and swelling above the knee so I put some liniment on it.
The grain is fine, I double checked that again.
The tree that dad said they had been eating the bark from is not a locust tree. I looked up pics and this tree has little prickles, not actual thorns, that are on the main trunk, and I do believe it has white flowers that come up on it in the spring.
The closest tree I could find that resembles it is a Prickly Ash, also known as Devils Walking Stick Tree and Hercules Club. But...the symptoms associated with poisonings from horses eating it do not even come close to her symptoms.
So I have no idea.
We are also going to walk the back fence line tomorrow to make sure the neighbors back there haven't tossed anything over.
Gah!! I hate not knowing what it is.

If you need any other info don't hesitate to ask. I've had her 6 years and have had her since she was 3 months old so I know her history pretty well.
I don't think it's an HYPP attack either.

Sorry Pinto Tess, I didn't even answer your question

No, she was not sweating, she felt a little warm after it happened and was breathing slightly heavier. I think it must have scared her as much as it did me. She hasn't had any medication at all.
She had been standing there nice and calm, just fidgeting and moving around a little once I was done with her, then when I moved her over to her spot it happened. The only thing I had done with her before that happened was catch her in the pasture, let her graze in the yard, then I took her down to the barn and started grooming her.

HYPP can set in at any age and in varying degrees. Because it is a partial and temporary paralysis, this absolutely could be what you are seeing. The test (Google UC Davis) involves pulling hair out at the roots and costs only $50 I believe. Very affordable.

It also could be a stroke - not a true seizure but again involving temporary paralysis. Strokes can be due to any number of things from genetic disorders to brain tumors to old age (though you said she's 6 so doesn't sound like age to me).

I also had a horse with insulin resistance who once went into a diabetic shock. It looked a lot like you are describing and unlike a full seizure there was no paddling, just tremors of the legs, and no loss of bodily functions. It also only lasted a minute if that (from what I recall - this was many years ago).

Either way i'd say a veterinary visit is definitely in order. If you want to start with a call, explain the symptoms and go from there. Perhaps you can do the HYPP test for the just $50 and get some answers. Until you have it diagnosed by an equine medical professional, I would caution you to NOT RIDE HER as that could put you and her at serious risk were she to have an episode while under saddle.

..... I don't know if I would wait until tomorrow for the vet. We were talking about potential black locust poisoning weren't we when they coliced? Symptoms fromf poisoning by black locust include: Colic, Weakness Renal (kidney) failure Fast heart beat, Depression, and even loss of appetite. It can be fatal depending on how much they ate...

I don't want to scare you and I know you are upset already but I don't want you to be sorry that you didn't call the vet if it really is something that serious.

Sorry. Somehow I missed that you said it was not a locust tree after all.

In addition, horses that have had colic symptoms that are HYPP H/N can have an attack brought about as a result from the colic stress from hours to several days after the colic episode. It sounds like this very well may be the case here. I've included a link to an article from thehorse.com below (the AAEP publication) that has some helpful information.

The Horse | Hyperkalemic Periodic Paralysis and Colic

Please keep in mind that mild attacks can be nearly invisible to even the most attentive horseperson. "In cases of mild attacks, muscle tremors may be so subtle as to be detectable only by an experienced clinician performing EMG testing." (quote from The Horse | HYPP: Hyperkalemic Periodic Paralysis)

Slightly off topic but I find this statistic particularly alarming and evidence of people not taking this seriously and not breeding responsibly: What is particularly striking is that in the past 14 years of genetic testing, not only has the HYPP gene frequency not decreased, but there has been a two-fold increase in the number of horses with this homozygous gene frequency...It is possible that constant muscle stimulation from the disease itself leads to muscle definition and tone that is visually favored. Thus far, 4% of Quarter Horses are affected; meaning that approximately 160,000 individuals have this disease. these statistics are from the 2007 article here: The Horse | Hyperkalemic Periodic Paralysis: 14 Years Later

Some good information from Tufts on HYPP: Hyperkalemic Periodic Paralysis : Cummings School of Veterinary Medicine at Tufts University

UC Davis HYPP information: Horse HYPP
UC Davis HYPP test fees (HYPP is $50): Horse Tests

I sincerely hope that your horse is not HYPP positive, and again believe a vet will be the best person to talk to regarding your horse and potential issues. Please keep us posted and be safe. Lots of prayers for you and your horse.

Thanks for the replies.
Yep, the tree they were eating from didn't have actual thorns, they are called prickles, and the tree didn't look like a locust tree.
I know her sire's pedigree doesn't have Impressive, but because her dam wasn't registered I have no idea. She was a sorrel sabino Paint who was just a hair taller than Chanti now but very stocky, so I know it could be possible.
Chanti wasn't paralyzed, she was moving around, she was just leaning towards the right, then she backed up, hit the post, went sideways again and fell over.
I know it wasn't an HYPP attack but that still may be something I test for.
I want a CBC done for sure and I want to get both horses their shots.
I have looked all through my vet book and nothing sounds like what happened to her.

I am definitely calling the Equine Center tomorrow and I am not going to ride her or work her until she gets checked out. I was even leary of giving them grain tonight but I checked it all and I've been feeding that grain with no problems and I've fed it before.