I'm going to try to keep this as succinct as possible but it is still very long, I apologize!
Last spring, on one of the first warmest days we had, my gelding was laying in the sun taking a nap (perfectly normal for him all the time, no matter the season). It was around 2:00 PM. I got home early to trailer him to ride at an indoor. When he got up and came to the gate, he was REALLY wet on his neck, chest, and towards his girth, and along his flanks. It appeared to be sweat but because he was laying in the snow/wet ground, I also wasn't sure if it was some sweat and some water. All else was normal, I trailered him to ride, did so without any issues.
(Hindsight observation here): sometimes since the occurance above, I have brought him into the barn from summer pasture to ride, and once inside the barn, he breaks out in a much milder sweat...along the armpits/girth and shoulder, nowhere else. It goes away rather quickly, usually by the time I tack him up. All is fine.
Flash forward to last night. I got home around 5:00 PM, and he was laying in the sun. Normal for him to do so. I change my clothes, and when I come back out he is standing at the gate in his normal "I'm ready for my dinner" spot but did paw the ground a couple times. I hook up my trailer, go get him out of the field, load him on the trailer. He's kind of sleepy acting, after all, he was just cat napping in the afternoon sun. Loads normal on the trailer, stands quietly, nothing amiss. I head out to trailer him to ride (about a 15 minute drive in the trailer).
Same trailer I've ALWAYS used with him.
Didn't drive any different than I ever have driven with him.
Unload him when we get there, and he is SOAKED in sweat, from his ears to his flanks, sweat is DRIPPING onto my trailer floor. THe only place there wasn't sweat was his legs and his back where the saddle would sit.
I am not too alarmed since this has happened before (first incident described above) but as I'm brushing him, he has a hind foot rested. His leg is trembling. I push him down so he is weight bearing on all feet, and his flanks and hindquarters are trembling. He is otherwise acting normal...eating hay, looking around, being himself. The sun was going down, so the shivering could've been related to being cold after sweating so much...I don't know for certain. He was perfectly willing to move forward/walk around, he didn't seem to be in any discomfort whether standing still or moving foward
I went and got the barn owner where I ride and she came out and took a look. She mentioned something called "Thumps" which after typing this out, I will go google. She said it has something to do with an electrolyte imbalance. We give him some electrolytes and I walk him around.
He is no longer actively sweating but still wet from previously. I walk him around and he seems normal. I put him on a short lunge line (maybe 12' of rope) and just have him walk around me. He seems agitated, shaking his head like a fly is on him. Sometimes he gets annoyed with sweat as well, so I don't think too much about it. He then breaks into a trot on the lunge line, and he is regularly shaking his head and stretching his neck down like he's looking for a place to roll (but he does not do this behaviour at a walk...?)
He gernerally seems very agitated on the lunge line, so I stop walking him and head back to the trailer. He still wants to eat hay.
Trailer him home, call my vet. He suggests 10 ccs of banamine orally, withhold any grain, and keep an eye on him. The vet thinks he may have had a "gas bubble" that made him more uncomfortable on the trailer ride.
This morning, horse is normal, all is well, no more sweating, he ate his breakfast, nothing amiss.
So, to wrap this up:
Horse randomly sweating
muscle shaking (although I"m not positive that wasn't from being cold after getting so sweaty because it's not THAT warm here yet)
Both instances happened in the spring
any instances that happened later in the summer weren't nearly as severe in regards to sweating, very mild
Agitated when trotting with head shaking involved
His daily feed is hay, pasture (although not much right now), 1 lb of TC 30%, 1 cup of flax, 2 tsp yea-sacc top dressed, and probably 1/2 lb alfalfa cubes all soaked together with a lot of water, its like soup when he eats it, really runny soup.
He drinks very well, always a good water drinker.
Dewormed last month with Quest Plus.
Had his teeth done on Saturday (4/27)
ETA: He did NOT have a temperature, it was 99.5 within an hour after this incident occurred.
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