No, in the book im looking at it says "Hyperkalemic Periodic Paralsis. As the three word title, has no work beginning with Y the correct abbreviation is /HPP/" But you are right AQHA and APHA use HYPP.
OK, Delete...positive thoughts!! (Isn't this what happens to first year med students when they think they have everything they read? J/K) The books and interent can be detrimental and helpful...all in the same breath. Have your baby tested for peace of mind. IF he does have Hypp, there are GREAT resources out there to control it. Key is to get him help NOW!!!! (I'm sure you have already taken these measures)
I truly feel ANY horse with the IMPRESSIVE line needs to be tested and tested again. You just can't be too safe, right?
Good luck! We'll all be praying for him (and you)!! (fingers crossed!)
Also I wanted to metion. He is a 2yr old and still fits into a yearling halter. Has since I have had him. Oh & I can seriously push him over if I tried hard enough. I was trying to see how weak he was. I grabbed his tail and pulled while he walked. He could hardly walk correctly. Then I shoved him lightly, he almost stumbled over. Ugh :(
I'm assuming your horse is not registered, if he were then the parents would be listed as HYPP/NN on the papers and you could find ease of mind through that. Do you know the parents registered names? Sometimes you can look them up on line, if they are AQHA registered you can pull the information online and see if they are. I'm not sure about the Appy registration, whether it shows on their papers or not. If both parents are HYPP/NN then your horse cannot have the disease. It really sounds like you need to call the vet out because there is something definitely going on. The problem is, what you have described can be anything from HYPP to EPM to plant poisening. Alot of times there will be somethign in your pasture I.e. Acorns or buttercups that are poison. Alot of horses will not eat them, but babies are babies. You can order the test for peice of mind but if it were me, rather then spend $50 at a time to diagnose myself... I'd spend $125 for the vet to take the tests, they can rule a number of things out at once. Just tryign to be helpful though.....
When I got my mare, there was nothing on her papers that said her father was N/H. I only found out about hypp though this forum. And I did the whole $50 to get her checked, and I found out she does have hypp.
While I agree that it could be something other than hypp, I think getting the horse tested to rule that in or out is the best way to go.
How tall is your baby now? The question about the halter could be no big deal because, depending on the bloodlines and what type of body style the horses you're baby has in him will depend on the head... Some Quarter horses (alot of foundation ones) have big heads but the Impressive horses have smaller heads, alot of them will be huge horses in tiny little cob sized halters and bridles... how tall is your baby?